UNIVERSITY OF CALIFORNIA 
 
 COLLEGE OF AGRICULTURE 
 
 AGRICULTURAL EXPERIMENT STATION 
 
 BERKELEY, CALIFORNIA 
 
 FRUIT SPOILAGE DISEASES 
 
 OF FIGS 
 
 RALPH E. SMITH and H. N. HANSEN 
 
 BULLETIN 506 
 January, 1931 
 
 UNIVERSITY OF CALIFORNIA PRINTING OFFICE 
 
 BERKELEY, CALIFORNIA 
 
 1931 
 
TABLE OF CONTENTS 
 
 PAGE 
 
 Introduction 3 
 
 Nature of the fig 4 
 
 Caprification 15 
 
 Souring 18 
 
 Investigations on souring 23 
 
 Further aspects of the problem of souring 30 
 
 Thrips 35 
 
 The fig mite (Eriophyes fici Ewing) 36 
 
 Predaceous mites in figs 38 
 
 Splitting 40 
 
 Mold 43 
 
 Sunburn 44 
 
 Smut 47 
 
 Surface spotting of figs 49 
 
 Endosepsis 52 
 
 Control of endosepsis by disinfection of caprifigs 58 
 
 Injection method 58 
 
 Dipping method 59 
 
 Methods used in state-wide endosepsis clean-up of 1928 59 
 
 Shortage of crop 62 
 
 Removal of mamme figs 62 
 
 Disinfection of mamme figs 62 
 
 Caprification of the profichi 64 
 
 Caprification of edible crop 64 
 
 Results of the campaign of 1928 64 
 
 Endosepsis clean-up in 1929 65 
 
 Results of endosepsis control of 1929 69 
 
 Control of endosepsis: General discussion 71 
 
 Location of caprifig trees 71 
 
 Varieties of caprifig 75 
 
 Complete removal of mamme figs necessary 76 
 
 Time of removing mamme figs from trees 77 
 
 Storing and handling mamme figs 77 
 
 Disposal of surplus mamme figs 77 
 
 Time for dipping and caprifying 77 
 
 Incubation of mamme figs 77 
 
 Dipping and caprifying 78 
 
 Use no untreated caprifigs 81 
 
 Caprification of Calimyrna crop 81 
 
 How often must clean-up for endosepsis be practiced? 82 
 
 Individual versus district clean-up of endosepsis 83 
 
 Literature cited 83 
 
FRUIT SPOILAGE DISEASES OF FIGS 
 
 EALPH E. SMITHi and H. N. HANSEN2 
 
 INTRODUCTION 
 
 The fig was one of the first of the typical semitropical fruits of 
 the Mediterranean region to be introduced into California. For tree 
 growth and fruit production it found itself perfectly at home in an 
 entirely congenial habitat. So long as the fruit was used for local or 
 home consumption, and particularly while the comparatively disease- 
 free Black Mission 3 variety predominated, the fig was considered 
 almost immune to pests and diseases. 
 
 When plantings of the Adriatic and Calimyrna varieties began to 
 assume considerable proportions and the problem of pollinating the 
 latter variety had been solved by the introduction and establishment 
 of the blastophaga insect, the earlier writers were most enthusiastic 
 over the prospects of fig culture in California (Howard, 1901 ; 
 Roeding, 1903; Shinn, 1915 ). 4 Some of them anticipated the time 
 when California would furnish not only the entire fig supply of the 
 United States but even extend into the markets of the world at large, 
 on account of the superior quality and condition of her product. 
 Gradually, however, with the more extended planting of the white fig 
 varieties, the situation described in the following paragraphs came 
 into existence, and the production has scarcely been maintained at 
 even the figures quoted. 
 
 The situation in figs has been described as follows (Phillips, Smith, 
 
 and Smith, 1925, p. 4) : 
 
 The fig deserves to be one of California's best commercial fruits. It shares 
 with the olive and grape the distinction of being one of the oldest cultivated 
 fruits. It is nutritious, appetizing, of attractive appearance, and wholesome. 
 The fruit has a great variety of uses, not only in the usual dried form, but also 
 for eating fresh and in such manufactured forms as jam, marmalades, preserves, 
 canning, candy, bakery products, breakfast and health foods, beverages, and 
 medicinal preparations. The well-known salutary properties of dried figs lend 
 themselves particularly well to advertising. The fig is one of the healthiest 
 
 1 Professor of Plant Pathology. 
 
 2 Assistant Plant Pathologist in the Experiment Station. 
 
 3 The Mission is a black, and the Adriatic a white-skinned fig, planted 
 extensively in California. The Calimyrna is the 'Lob Injir' variety of Smyrna, 
 which requires pollination (caprification), not necessary with the other varieties 
 mentioned. 
 
 4 See "Literature Cited," at the end of the bulletin, for complete data on 
 citations, which are referred to in the text by author and date of publication. 
 
4 University of California — Experiment Station 
 
 of fruit trees, easily suited as to soil and moisture, and well adapted to a wide 
 area in California and (for dried figs) to no other portion of the United States. 
 The quality of California-grown figs at their best is admittedly unsurpassed. 
 
 And yet, it must be said that fig culture is not so well established in Cali- 
 fornia as that of many other fruits, and considerable difficulty is experienced 
 in disposing of the comparatively small dried-fig crop of the state at even 
 moderate prices. California produces less than 10,000 tons of dried figs per 
 annum (9,000 tons in 1923), as compared with 25,000 tons of walnuts, 100,000 
 tons of prunes, and 250,000 tons of raisins. Even though foreign competition 
 is keen, exchange rates low, and fig production in the Mediterranean countries 
 very large, it seems remarkable that this small tonnage of California-grown figs 
 cannot readily be marketed at good prices. 
 
 The greatest obstacle to the success of the fig industry at the present time 
 is the occurrence of various forms of rotting, souring, and molding of the fruit, 
 which at times becomes very abundant and troublesome. Such defects reduce 
 yields and make it very difficult to put up a high-grade, dependable pack, of 
 sufficient quality to compete on better than even terms with the foreign product, 
 and one upon which the arts of advertising and salesmanship can confidently be 
 practiced. It is only by such advertising, backed by superior, uniform quality, 
 that our increased production of other foreign-competing fruit products has 
 been successfully marketed. 
 
 The excessive amount of spoilage which, occurs in figs has been the 
 subject of investigation by the Experiment Station for several years. 
 This trouble was regarded at first as a normal, or at least an unavoid- 
 able consequence of climatic influences, but more and more evidence 
 has been obtained to suggest that it may be due primarily to specific 
 infections, dependent like other plant diseases upon the presence of 
 certain pathogenic organisms, the proper agents of transmission, and 
 favorable environmental conditions. Any real knowledge and positive 
 control of fig spoilage must therefore depend primarily upon a 
 thorough, fundamental understanding of these three factors. The 
 present publication is intended to bring together rather fully the 
 available evidence upon the subject, which is at present in a very 
 scattered condition, and also to present certain new information which 
 is published here for the first time. Material has been freely drawn 
 from California Agricultural Experiment Station Bulletins 319 and 
 387, Circular 311, and Hilgardia, Volume 2, No. 7. 
 
 NATURE OF THE FIG 
 
 The fig is a nearly closed, more or less hollow receptacle, the inner 
 walls of which are lined by very small flowers when immature and 
 by the seed-like fruits when ripe. It is not, therefore, a fruit in the 
 strict botanical sense of the word, but an aggregration of fruits lining 
 the cavity of a hollow receptacle, technically a synconium, with an 
 opening at the center of the flattened end which is closed during the 
 
Bul. 506] 
 
 Fruit Spoilage Diseases of Figs 
 
 early stages by overlapping scales or bracts (fig. 1). After the fig 
 begins to ripen and soften these scales loosen and an opening is 
 formed, the diameter of which varies from 2 to 10 millimeters, accord- 
 ing to the variety of fig. This opening is usually referred to as the 
 'eye' of the fig. Figure 2 shows successive stages of the opening of 
 the eye in the Adriatic and Kadota 5 varieties. 
 
 Fig. 1. — Interior of nearly mature Calimyrna fig, twice enlarged, at the stage 
 when ripening begins and pulp is about to soften and liquefy. It is at this 
 stage that decay and souring begin. The whole problem of control of fig spoilage 
 depends upon knowing what organisms cause this, when and how they get into 
 the fig, and how they may be kept out or their development prevented. 
 
 As the edible fig ripens, the outer wall becomes thickened, fleshy, 
 and sweet, and the pedicels and calyces of the individual florets become 
 enlarged and pulpy. Quite suddenly at full maturity the flesh of each 
 floret becomes almost liquid and very sweet. The whole inside of the 
 fig then breaks down, coalesces, and dries into a pulpy, sirupy, and 
 finally a homogeneous, gelatinous mass, in which the seeds are 
 embedded. Figure 1 shows a longitudinal section of a nearly ripe 
 Calimyrna fig with the eye at the end, the enlarged fleshy florets each 
 with one seed, and the outer wall. 
 
 s The Kadota is a white fig planted extensively in California for preserving. 
 It is the Italian variety 'Dotatto,' of which word the name is a corruption. 
 
University of California — Experiment Station 
 
 ' '■; ' 
 
 m^^p 
 
 Fig. 2. — Successive stages in the opening of the eye of the fig, from top 
 to % bottom. Left, Adriatic variety; right, Kadota variety. 
 
Bul. 506] 
 
 Fruit Spoilage Diseases of Figs 
 
 The saccharine pulp enclosed in the soft, outer wall forms an ideal 
 medium for saprophytic microorganisms and insects, and the fig, more 
 than almost any other fruit, seems unprotected from such attacks. 
 That it does under favorable conditions escape is due mainly to two 
 circumstances : First, so long" as the outer wall is intact the only ingress 
 to the interior pulp is through the apical opening or eye, which does 
 not open until the fig is nearly ripe. This helps to exclude insects 
 and even microorganisms until the susceptible period is nearly past. 
 Second, in the rainless summer climates to which the fig is best 
 adapted, a comparatively rapid evaporation of water and concen- 
 tration of sugar begins at about the time when the eye opens and final 
 ripening begins. Soon after this stage is reached the fruit normally 
 falls from the tree. Normally, therefore, before the fig falls to the 
 ground the pulp has become sufficiently low in moisture and high in 
 sugar to prevent or arrest decomposition by spoilage organisms. The 
 duration of the susceptible period, however, or inversely the rate of 
 dehydration, practically governs the progress of such decomposition. 
 This idea is well expressed by Coit (1921) in the quotation on page 21. 
 
 Table 1 shows the percentage of moisture and sugar in figs as they 
 naturally ripen and dry. 
 
 TABLE 1 
 
 Analysis of Adriatic Figs at Different Stages of Maturity 
 
 Type 
 
 Per cent moisture 
 
 Per cent sugars 
 
 3 
 
 83.25 
 
 9.12 
 
 4 
 
 80 80 
 
 12.92 
 
 5 
 
 74.65 
 
 18.87 
 
 6 
 
 61.00 
 
 33 04 
 
 7 
 
 52 45 
 
 46.36 
 
 8 
 
 42.50 
 
 46.04 
 
 9 
 
 29.00 
 
 56 85 
 
 10 
 
 13.10 
 
 69.58 
 
 From: Phillips, E. H., E. H. Smith, and R. E. Smith. 
 Fig smut. California Agr. Exp. Sta. Bul. 387:19. 1925. 
 
 Figures 3, 4, and 5 show the normal maturing, breaking down, 
 and drying in Adriatic figs. The stages of development shown in these 
 figures represent a series chosen by Phillips, Smith, and Smith (1925) 
 to form a basis for reference, and this series has been commonly used 
 as a standard in later work. These types are described as follows : 
 
 1. Fruit not quite full grown, still green and hard. 
 
 2. Full grown, eye scales beginning to loosen. 
 
 3. Eye fairly well opened, fruit still green and firm. 
 
 4. Slightly yielding to pressure, pulp succulent, but still firm. 
 
8 
 
 University of California — Experiment Station 
 
 Fig. 3. — Stages of maturity in Adriatic figs, types 1-4. 
 (From Bulletin 387.) 
 
Bul. 506] 
 
 Fruit Spoilage Diseases of Figs 
 
 Fig. 4. — Stages of maturity in Adriatic figs, types 5-7. 
 (From Bulletin 387.) 
 
10 
 
 University of California — Experiment Station 
 
 Fig. 5. — Stages of maturity in Adriatic figs, types 8-10. 
 (From Bulletin 387.) 
 
Bul. 506] 
 
 Fruit Spoilage Diseases of Figs 
 
 11 
 
 5. Fig ripe as for picking for fresh shipment. No shriveling, 
 
 pulp opaque. 
 
 6. Skin slightly shriveled, pulp somewhat translucent. 
 
 7. Distinct shriveling, contents still red, not sticky. 
 
 8. Much shriveled and skin beginning to discolor. Pulp mahogany 
 
 color, slightly sticky. 
 
 9. Skin brown, but flexible, pulp brown, translucent, sticky. Stage 
 
 of completed normal drying. 
 10. Overdry, stiff, and hard. Flowers stand out separately in pulp. 
 
 Fig. 6. — A Milco caprifig tree, showing the mamme crop which must be 
 removed and destroyed or treated in order to eradicate endosepsis. (From 
 Bulletin 319.) 
 
 The fig is a diecious, insect-pollinated plant, the staminate flowers 
 and the edible fruit being borne on different trees. The male tree 
 (figs. 6, 7) is known as the caprifig. In its receptacles (fig. 8) are 
 borne chiefly two types of flowers. The staminate flowers which 
 produce the pollen are arranged, in most varieties, just inside the 
 eye, and the gall flowers (modified female flowers) occupy the rest 
 of the cavity. The gall flowers have a very short style (fig. 9), par- 
 ticularly suited to the needs of the pollinating insect, as will be 
 explained later. The caprifig bears a succession of fruit (fig. 10) 
 
12 
 
 University of California — Experiment Station 
 
 Fig. 7. — Gathering the profichi crop for eaprifying the edible, Calimyrna 
 
 figs. (From Bulletin 319.) 
 
BuLu 506] 
 
 Fruit Spoilage Diseases of Figs 
 
 13 
 
 known as the 'mamme' or overwintering crop, the 'profichi' or spring 
 crop, which is the important one in relation to the edible figs, and 
 the 'mammoni' or fall crop. This succession of crops provides the 
 proper habitat for the insects throughout the year. The caprifigs are 
 not edible. They are usually rather small and nonsucculent, the size 
 varying with the variety. 
 
 The female tree also bears a succession of crops, one produced in 
 the spring on the wood of last year's growth and a second in the 
 summer on the new growth. Both crops are edible, but in most cases 
 
 Fig. 8. — Caprifigs (profichi) showing in upper center the staminate, pollen- 
 bearing flowers, with the blastophaga galls in the interior of the fig below. 
 (From Bulletin 319.) 
 
 the second is the one of principal commercial importance. The 
 receptacle of the edible fig is lined with a single kind of flowers, the 
 pistillate, which resembles the gall flowers of the caprifig except that 
 the style is much longer (fig. 9). 
 
 The edible fig varieties are of two types, the parthenocarpic, or 
 varieties which develop fruit without pollination, and the varieties 
 that require pollination (caprification). The important varieties of 
 the first category, grown in California, are the White Adriatic, the 
 Black Mission, and the Kadota (Dottato), while the varieties which 
 require pollination are chiefly those called Calimyrna, Stanford, and 
 
14 
 
 University of California — Experiment Station 
 
 San Pedro (second crop). The Calimyrna and Stanford were intro- 
 duced into California from Asia Minor, the former being the com- 
 mercially famous 'Lob Injir' of Smyrna. 
 
 ■nHnoMuw 
 
 Fig. 9. — Above, staminate flowers of caprifig (X 10). Below, right, short- 
 styled gall flowers of caprifig; left, long-styled flowers of edible fig (X 5). 
 (From Bulletin 319.) 
 
Bui* 506] 
 
 Fruit Spoilage Diseases of Figs 
 
 15 
 
 CAPRIFICATION 
 
 The process of pollinating" the pistillate flowers of the fig is known 
 as caprification. It is effected through the agency of a small hymen- 
 opterous insect, Blast aphaga psenes L. (B. grossorwm Grav.). Eisen 
 (1901), Vallese (1904), Rixford (1918), Condit (1922), and Grandi 
 (1920, 1923), have given extensive accounts of caprification and its 
 agent. A brief account of the process is here given. 
 
 Fig. 10. — Caprifigs, showing blastophaga insects passing from mamme 
 figs (below) to profichi (above). (From Bulletin 319.) 
 
 The male or caprifig, as already stated, has three crops of fruit 
 during the year. The figs of the mamme crop, which may be taken as 
 a starting point, are formed in the fall and remain on the trees over 
 the winter. In early spring the new figs of the next crop appear on 
 the woody twigs of the previous year's growth. These are the profichi. 
 At this time the blastophaga insects are present in the galls or enlarged 
 florets of the mamme figs, where they have passed the winter. With 
 
16 University of California — Experiment Station 
 
 the first warm days of March or April (the exact time varying with 
 locality and season) the profichi reach the receptive stage and the 
 insects in the mamme figs begin to function. The adult males (fig. 12) 
 issue first from their galls, fertilize the adult females while the latter 
 are still in their galls (fig. 13), and open the way for them to emerge 
 later (fig. 14). The males,. as a rule, never leave the figs. The females 
 (fig. 11) come out through the eye of the fig, fly to nearby profichi 
 (fig. 10) (to which they are apparently attracted by the odor) and 
 enter by forcing their way through the unopened eye of the young 
 fig, often losing their wings in the process. The mamme figs ordinarily 
 contain no pollen and pollination is not required to set the profichi. 
 
 In the gall flowers of the profichi the blastophaga inserts its 
 ovipositor through the style and deposits an egg in the ovule. The 
 egg hatches and the larva develops inside the gall, where it finally 
 pupates. Meantime the fig has grown to full size. In early summer 
 (June) the profichi and the blastophaga contained in them have 
 become mature, and on the new growth of the caprifig trees another 
 crop of figs, the mammoni, has appeared. Simultaneously there has 
 developed on the edible fig trees an abundant crop of young figs. 
 Another crop of female blastophaga issue from the profichi and enter 
 the mammoni figs on the same tree and the female (edible) figs on 
 any nearby trees, whether they are of the Smyrna type which require 
 pollination or others which do not. 
 
 The profichi produce a large amount of pollen from stamens just 
 inside the eye. As the female blastophaga leave the profichi they 
 rub against the staminate flowers which surround the orifice and shed 
 their pollen at that time. The insect may then carry the pollen into 
 a fig of an edible variety or she may enter another caprifig, perhaps 
 on the tree bearing the one from which she just emerged. 
 
 The majority of the insects travel but a short distance, although 
 occasionally caprification occurs in figs which are several miles distant 
 from the nearest caprifig tree. It is customary to interplant caprifig 
 trees to some extent in Calimyrna orchards or in a block at one side. 
 In order to obtain uniform caprification the profichi are usually 
 gathered from the trees (fig. 7) and hung in small wire baskets in the 
 edible fig trees. Extra mamme figs are sometimes used in the same 
 manner in the caprifig trees to increase the setting of the profichi. 
 In the male figs caprification is not necessarily a process of pollination 
 but is primarily a setting of the fruit due to a stimulus derived from 
 the parasitizing of the ovaries by the insects. 
 
Bul. 506] 
 
 Fruit Spoilage Diseases of Figs 
 
 17 
 
 Fig. ]1.— The female blastophaga (X 27). (From Bulletin 319.) 
 
 Fig. 12.— The male blastophaga (X 27). (From Bulletin 319.) 
 
18 University of California — Experiment Station 
 
 In the case of edible figs the female blast ophaga (fig. 11) enters 
 the young fruits for the purpose of oviposition and in so doing carries 
 pollen from the caprifig. Oviposition, however, is not effected, because 
 the styles of the female flowers are too long for the blastophaga to 
 oviposit. The insect usually perishes in this vain attempt, but not 
 without an effect, for the introduction of the pollen fertilizes the 
 flowers and causes the fruit to mature fertile seed. Without such a 
 stimulation the fruit of the Calimyrna, San Pedro, and Stanford 
 varieties does not set but drops when about one-fourth grown; that 
 of the parthenocarpic varieties continues growth to maturity, but the 
 seeds are not fertile (phenospermic). If the fruit of such varieties 
 (Mission, Adriatic, Kadota) should be accidentally caprified, as often 
 happens in the vicinity of caprifigs, fertile seeds are produced and the 
 character of the fruit is slightly changed and sometimes improved. 
 
 The mammoni and mamme figs contain little or no pollen and for 
 the setting of the mamme crop by the mammoni, and the profichi by 
 the mamme, no pollen is required. The mammoni figs sometimes 
 contain a few fertile seeds, but the chief function of this crop is to 
 perpetuate the insect in the galls. They mature in the fall and caprify 
 most of the mamme figs in October. 
 
 The caprifigs used in California are classified into a number of 
 named varieties which differ considerably from one another. 
 
 SOURING 
 
 Up to a comparatively recent time practically all the spoilage in 
 figs in California was referred to as ' souring ' or 'fermentation' and 
 thought to be the natural, unavoidable consequence of such influences 
 as cool nights, moist winds, slow drying, rain, overirrigation, or high 
 water table. Roeding (1903), for instance, says "In soils where the 
 water levels throughout the year stand close to the surface, Smyrna 
 figs should not be planted, for in such locations .... there is a possi- 
 bility of some of the figs souring should cool weather set in during the 
 
 drying season In the early part of the harvesting season of 1901 
 
 westerly winds, which always carry a great deal of moisture, prevailed, 
 and in consequence of this many of the figs soured." Shinn (1915) 
 says, "The fruit in some districts in some seasons ferments on the 
 trees ('fig sour'). This sometimes seems to come from overirrigation, 
 sometimes from lack of vitality, and most often occurs in very tender 
 and juicy varieties." 
 
Bui,. 506] 
 
 Fruit Spoilage Diseases of Figs 
 
 19 
 
 Fig. 13. — Eight, male blastophaga emerging from gall; left, male 
 impregnating female inside gall. (From Bulletin 319.) 
 
 Fig. 14. — Female blastophaga emerging from gall. (From Bullein 319.) 
 
20 University of California — Experiment Station 
 
 Wickson (1926, p. 383) says, "The intrusion of the coast influences 
 borne eastward by the winds of summer gives a night temperature too 
 low for ripening of some of the varieties, which turn sour upon the 
 trees Even in southern California fig-souring is quite prevalent. ' ' 
 
 Lelong (1892) makes similar suggestions. 
 
 As early as 1892 Newton B. Pierce (1893), the pioneer plant 
 pathologist of the Pacific Coast, recognized the importance of patho- 
 genic organisms and insect carriers in fig spoilage. He states: 
 "Another of the industries of the state which has been gradually 
 extended of late is seriously threatened. This is the growth and curing 
 of figs. It has been observed since the cultivation of this fruit has 
 been attempted that the growers had to contend with a destructive 
 fermentation of the fruit which often caused the loss of nearly the 
 entire crop." Pierce found that the fruits spoiled both while on the 
 tree and on the drying trays and states further, ' ' A series of field and 
 laboratory investigations resulted in the isolation of an organism 
 capable of exciting fermentation. This proved to be a yeast." From 
 inoculations made with pure cultures of this organism the typical 
 fermentation was produced in figs. It is further stated that "The 
 fruit is inoculated by insects, the yeast cells being carried by them to 
 the ripening fruits. ' ' 
 
 Eisen (1901, pp. 178-179) came to the same general conclusion. 
 ' ' The souring of the figs is directly caused by a fungoid fermentation 
 undoubtedly related to the fungus which causes acute fermentation 
 in other sweet substances such as wine. A more distinct cause of 
 souring is the want of proper sweetness in the figs, too much water 
 in the soil, or unsuitable soil. Figs which grow in moderately moist 
 ground sour less than those which grow in wet soils To counter- 
 act this tendency to souring the soil should be kept dry, though exces- 
 sive dryness will also injure the figs As long as the eye is closed 
 
 bacteria and fungi are kept out and no fermentation can take place. 
 There is no doubt that the principal function of the eye of the fig is to 
 keep out bacteria and insects, and the closed form of the fig receptacle 
 is undoubtedly effected by nature in order to prevent parasites from 
 spoiling the sugary juice of the fig." 
 
 Howard (1901) also suggested insect transmission of souring, while 
 Condit (1917, p. 16) and Hodgson (1918) mention a similar possi- 
 bility in the case of the fungus infection called smut. Condit (1919) 
 states that souring is only another name for fermentation caused by 
 the action of yeasts, molds, and bacteria, of which yeasts are probably 
 the most common. He attributes the introduction of these organisms 
 
Buu 506] Fruit Spoilage Diseases of Figs 21 
 
 into figs to insects, particularly "small beetles" and occasionally the 
 vinegar fly. Concerning' the relation of soil moisture and climatic 
 conditions to souring the following statement is made : 
 
 Yeasts, which are probably the most common organisms to cause figs to sour, 
 cannot grow in the interior of the fruit until it becomes fairly mature and 
 moistened with exudation from the pulp of the sweet, watery juice. The growth 
 of the yeast under such conditions changes the sugar present into alcohol and 
 carbon dioxide and, if long continued, causes the complete softening of the 
 entire fruit through the breaking down of the cell walls. The sour flavor of 
 such figs is probably due also to bacterial action of the nature of lactic acid 
 and alcoholic fermentation. 
 
 The growth of the yeast is dependent also upon the degree of concentration 
 of the sugar in the juice of the fruit. There is what we may call a neutral 
 point at which the yeast cells remain in a resting state. If the moisture in 
 the fruit increases and the solution of sugar becomes diluted, the yeast becomes 
 active and starts into growth. If, on the other hand, the moisture in the fruit 
 decreases and the sugar solution becomes more concentrated, the growth of the 
 yeast is inhibited and the fruit develops normally. As already explained in 
 regard to splitting, the percentage of humidity in the air influences the amount 
 of moisture in the fruit and we can now understand why damp, foggy weather 
 increases the tendency for some varieties of figs to sour. Excessive irrigation 
 or a high water table also brings about conditions favorable to souring for the 
 same reasons. 
 
 Varieties of figs differ greatly in their susceptibility to souring The 
 
 so-called Kadota is known as a fig which practically never sours in the San 
 Joaquin Valley. The Mission and the Brown Turkey very seldom sour. In 
 what respect are these varieties resistant to the yeast organism which causes 
 souring? I have no data to prove my assertion but I believe it is due to the 
 earlier concentration of sugar in the maturing fruit. A Kadota or Brown 
 Turkey fig tastes sweeter in the stages preceding full development of color 
 and full maturity than the Adriatic fig does at that stage and for that reason 
 the former varieties are more suitable for the fresh fruit market. 
 
 Coit (1921), on the basis of considerable field work, reached 
 
 similar conclusions. As to the factors which influence souring he 
 
 states the following: 
 
 Inasmuch as the atmosphere is filled with spores of many kinds of yeasts, 
 molds, smuts, and bacteria, and since the eye of the Smyrna fig is open, it is 
 unavoidable that these agents gain access to the interior of the majority of the 
 figs. If the juice were all retained within the cells, then only pathogenic 
 organisms, or those capable of penetrating the cell wall, would accomplish 
 decay. As the sap is free, however, all the organisms within the fig will have 
 an opportunity to grow, being limited only by the concentration of sugars in 
 the sap. 
 
 We have come to the conclusion that the term 'souring' is a very unfor- 
 tunate and misleading term. A dried fig is one that is preserved by the density 
 of its own juice. A sour fig is one which has suffered decay on account of lack 
 of juice density. As there are many different kinds of rots in apples and other 
 
22 
 
 University of California — Experiment Station 
 
 fruits, so there are many kinds of decay in figs, each with a characteristic 
 appearance, odor, and taste. There are molds, mildews, and smuts of various 
 kinds, the growth of each of which is limited by a different density point of 
 the juice. With a very thin juice we find a number of them working together; 
 as evaporation concentrates the juice the growth of one after another is stopped. 
 Wild yeast appears to be able to grow on a very dense medium, and being one 
 of the last to stop growth, is largely responsible for souring. We have found 
 
 Fig. 15. — Sour fig. (From Circular 311.) 
 
 yeast in what appear to be perfectly sound figs; and are of the opinion that 
 it may clarify the situation somewhat if we consider all Symrna figs as potential 
 sour figs and recognize the best grades of packed figs as those in which progress 
 of 'souring' was stopped very soon after it began. The successful curing of 
 Smyrna figs will depend, therefore, on the density of the sap when released 
 from the cells and the speed with which the water is removed by evaporation. 
 The first factor is dependent upon the relation between available soil water 
 and the transpiration from the leaves. The second factor depends upon 
 evaporating power of the air. 
 
Bul. 506] 
 
 Fruit Spoilage Diseases of Figs 
 
 23 
 
 Coit's conclusion is that excessive soil moisture or atmospheric 
 humidity produce a lowered concentration of the sap of the fig and 
 thus render souring unavoidable. 
 
 Investigations on Souring. — The first comprehensive investigation 
 of fig spoilage by laboratory methods was that begun by Phillips in 
 1920 and reported on in part by Phillips, Smith, and Smith (1925). 
 
 Fig. 16. — Sour figs dried on tree, showing ' black-neck, ' 'blue-stem,' 
 and 'black-end' conditions. (From Circular 311.) 
 
 These workers, whose investigation was mainly directed at the so- 
 called 'smut' disease, examined and cultured large numbers of figs of 
 the Adriatic variety at various stages of maturity in order to deter- 
 mine the time of the initial entrance of microorganisms into the fruit, 
 the identity of the organisms concerned, and the mode of transmission. 
 As a basis of investigation ten representative stages in the develop- 
 ment of the fig (see figs. 3, 4, and 5 and their description on page 7) 
 were arbitrarily chosen. The earliest of these stages represents the 
 condition of the fruit when it is not quite full grown, still hard and 
 green and with the eye scales tightly closed. At stage 3 the fig is still 
 hard and green but full grown and with the eye partly open. Stage 5 
 
24 University of California — Experiment Station 
 
 represents figs in the condition when they are picked for the fresh fig 
 market, the eye being" fully open and the pulp beginning to soften. 
 The later stages represent successive steps in the ripening and drying 
 of the fig up to that of complete drying. Table 1 (p. 6) shows the 
 respective percentages of moisture and sugar of figs at these different 
 stages. 
 
 On the basis of individual examinations and cultures from nearly 
 10,000 figs, Phillips, Smith, and Smith concluded that, under the 
 conditions of their investigation, the interior of uncaprified Adriatic 
 figs is sterile (free from fungi, bacteria, and yeasts) until the time 
 when the eye opens and the pulp begins to soften (stages 4—5). They 
 were of the opinion that no rotting or souring takes place without such 
 organisms, and that they are introduced mainly by insects and not by 
 air currents, basing this conclusion on the fact that spores of the 
 black-smut fungus (Aspergillus niger) did not cause infection or gain 
 entrance when blown forcibly with an atomizer against the open eyes 
 of figs at the susceptible stage. Similar spores introduced into the 
 interior cavity of the fig with a. needle or in a watery suspension by 
 means of a pipette produced infection very readily. 
 
 Further evidence that insect transmission is the principal factor 
 in the introduction of microorganisms into figs was deduced from an 
 experiment in which two large fig trees were inclosed with a cheese- 
 cloth-covered frame to exclude insects (fig. 17). No sour figs developed 
 on these trees although souring was abundant on all the other trees in 
 the orchard. An excessive amount of splitting occurred in the figs 
 on the enclosed trees but even these did not sour. The temperature 
 within the tent was somewhat lower and the humidity greater than on 
 the outside. 
 
 These workers obtained a considerable variety of fungi and bacteria 
 from mature figs, including various species of yeast, Aspergillus, 
 Rhizopus, Alternaria, Cladosporium, Penicillium, and Hormodendrum. 
 It was thought by them that the dried fruit beetle, Carpophilus 
 hemipterus (L.) (fig. 18), is the principal carrier of infection, since 
 this insect was found to be very abundant in ripening figs and its 
 appearance in them was coincident with the beginning of fruit spoil- 
 age. Most of the figs were sterile up to the time when the beetles 
 began to enter them, and the organisms which cause spoilage were 
 found very abundantly on the bodies of the beetles. The vinegar fly, 
 Drosophila ampelophila (Loew), was thought to be of secondary 
 importance. The experiment with the cheese-cloth tent just described 
 above was thought to give further evidence of the fact that the 
 exclusion of these insects prevented souring. 
 
Bul. 506] 
 
 Fruit Spoilage Diseases of Figs 
 
 25 
 
26 
 
 University of California — Experiment Station 
 
 m % 
 
 # -w # * * ^ • 
 
 Fig. 18. — Dried-fruit beetles issuing from decaying orange, covered with 
 disease germs and ready to attack figs. (From Bulletin 387.) 
 
Bul. 506] 
 
 Fruit Spoilage Diseases of Figs 
 
 27 
 
 Caldis (1927) in a study preliminary to his investigation of 
 another fig" disease, endosepsis, corroborated the work of Phillips, 
 Smith, and Smith in regard to the flora of Adriatic figs at different 
 stages of development. His results are summarized in table 2. 
 
 TABLE 2 
 
 Varieties, Localities, and Numbers of Parthenocarpio Figs Examined in 
 Determining the Flora of the Fig Eeceptacle (Stages 1-3) 
 
 
 Crop 
 
 Sacramento 
 
 Modesto 
 
 Fresno 
 
 Condition 
 
 Adriatic J 
 
 Mission J 
 
 Kadota J 
 
 San Pedro 
 
 First 
 
 Second 
 
 First 
 
 Second 
 
 First 
 
 Second 
 
 First 
 
 First 
 
 First 
 
 
 4 
 4 
 3 
 
 10 
 15 
 
 53 
 
 68 • 
 
 16 
 
 18 
 
 20 
 
 18 
 
 18 
 
 4 
 
 4 
 
 4 
 
 All sterile 
 All sterile 
 All sterile 
 All sterile 
 All sterile 
 All sterile 
 All sterile 
 
 White Ishia 
 
 All sterile 
 
 Brown Turkey 
 
 All sterile 
 
 Cordelia 
 
 10 
 5 
 
 All sterile 
 
 Miscellaneous 
 
 
 All sterile 
 
 
 
 
 
 
 From: Caldis, Panos D. Etiology and transmission of endosepsis (internal rot) of the fruit of the 
 fig. Hilgardia 2:298 table 1, 1927. 
 
 Smith and Hansen (1927) describe souring and state that it is 
 "caused by yeast followed by the action of bacteria and molds. It 
 is started by insects, especially the dried fruit beetle, Carpophilus 
 hemipterus (L.), entering the figs. It is spread by these and other 
 insects, especially the vinegar fly (Drosophila ampelophila (Loew))." 
 Cultures are reported in which it is shown that Carpophilus 
 hemipterus (L.) carries yeasts and some of the fungi commonly found 
 in figs (see fig. 19). 
 
 Caldis (1930) later investigated the cause and transmission of 
 souring in uncaprified Adriatic figs. He describes the disease as 
 follows : 
 
 In souring there is at first a change in the color of the pulp, which from 
 pink becomes colorless and subsequently turns watery. A pink liquid exudes 
 from the eye, dropping on the leaves or jellying at the eye [fig. 15]. Gas 
 bubbles are seen through the pulp and the skin in many cases becomes water- 
 soaked and loses its firmness. The pulp is disintegrated and smells strongly of 
 alcohol and in many cases is found covered by a white scum. The figs begin 
 to shrivel and dry up in this condition and they either drop to the ground or 
 hang on the twig, in the latter case giving rise to what is commonly called 
 'black neck' figs [fig. 16]. A dead spot or 'eye canker' is often found in the 
 bark at the point of attachment of such figs, as seen in the two twigs in 
 [figure 16]. Fermented figs lose their firmness, sag, and usually the pulp 
 becomes detached from the skin in the neck, which shrivels, dries up, and 
 
28 
 
 University of California — Experiment Station 
 
 turns dark. Fig souring is primarily an alcoholic fermentation, but subsequent 
 changes may take place while the fig is attached to the twig, on the ground, 
 or the drying board. The confmonest change is the action of acetic bacteria 
 on the alcohol with the production of acetic acid, which is readily discerned by 
 its pungent, strong odor. Ethyl acetate and other esters are probably formed. 
 
 This work was done with Adriatic figs in Fresno in 1924 and in 
 Davis in 1925. Caldis obtained a. large percentage of sonr figs by 
 confining the dried fruit beetle upon the figs on the tree in wire-cloth 
 
 at "Ss* 
 
 "♦* Jfc,' 
 
 Fig. 19. — Culture plate in which a dried-fruit beetle was placed, resulting 
 in abundant growth of molds, yeast, and bacteria. The black-dot areas are the 
 smut fungus. (From Circular 311.) 
 
 cages. The beetles bred and multiplied in the figs during the experi- 
 ment. In figs which were bagged or caged without beetles no souring 
 developed. Table 3 summarizes Caldis 's results. 
 
 By culturing sour figs Caldis isolated three prevailing species of 
 yeast, two of which (designated by Caldis as yeast A and yeast C) 
 produced typical souring when inoculated into ripe figs, while the 
 third type (yeast E) produced a different form of disease not of the 
 nature of typical souring. Yeast A was said to be of the Mycoderma 
 type; yeast C, the Apiculata; and yeast E, a Torula. The same yeasts 
 
Bul. 506] 
 
 Fruit Spoilage Diseases of Figs 
 
 29 
 
 were obtained regularly in cultures from Carpophilus. No other insect 
 was mentioned in this work. 
 
 For several years Messrs. Perez Simmons and W. D. Reed of the 
 United States Department of Agriculture, Bureau of Entomology, 
 have been located at Fresno carrying on investigations on the life 
 history and control of the dried fruit beetle. No results concerning 
 this work have as yet been published, but several popular addresses 
 have been presented at public meetings concerning the relation of this 
 insect to figs. The possibilities of trapping the beetle have received 
 much attention. It would appear that the practical control of Carpo- 
 philus in the orchard presents a difficult problem. 
 
 TABLE 3 
 
 Besults of Bagging Dried Fruit Beetles on Adriatic Figs (Caldis) 
 
 
 Number of cages 
 or bags 
 
 Number of figs 
 
 Figs sour 
 
 Figs not sour 
 
 With beetles — 
 Fresno — 1924 
 
 4 
 
 3 
 
 111 
 17 
 
 25 
 29 
 
 545 
 118 
 
 19 
 9 
 
 
 
 
 6 
 
 Davis— 1925 
 
 20 
 
 Without beetles — 
 Fresno— 1924 
 
 545 
 
 Davis— 1925 
 
 118 
 
 
 
 From all the work reported up to this point the following con- 
 clusions seem justified : 
 
 1. ' Souring ' of figs is due to fermentation of the internal saccharine 
 juices caused by specific yeasts. 
 
 2. Uncaprified parthenocarpic figs are internally sterile until they 
 have been entered by insects. After this they frequently contain and 
 are infected with yeasts, molds, and bacteria. This time usually 
 coincides with that when the eyes open and the figs begin to ripen. 
 
 3. The time of the opening of the eye and softening of the fig is 
 coincident with the first entrance of the omnipresent dried fruit 
 beetle, Carpophilus hemipterus (L.). The body of this insect is 
 heavily contaminated with the same microorganisms that occur in the 
 fig. 
 
 4. In a limited number of experiments where figs were enclosed with 
 paper, cheese-cloth, or fine-mesh wire screen, excluding Carpophilus 
 and equally large insects, souring was prevented. Souring developed 
 when beetles were placed in the bags. 
 
 5. It has not been conclusively proved that Carpophilus and 
 Drosophila are the only insect carriers of infection in parthenocarpic 
 
30 
 
 University of California — Experiment Station 
 
 figs or that all the infection is transmitted by any insect at all, since 
 in the caging and bagging" experiments other factors than insect 
 exclusion may have played a part. 
 
 Further Aspects of the Problem of Souring. — At the end of ten 
 years of study of the fig problem by members of this division, certain 
 observations affecting the above conclusions on souring are rather 
 outstanding; for instance, it is very evident that the term 'souring' 
 is a loose and indefinite one and may not always indicate specifically 
 the same condition. 'Sour' and 'not sour' may at times have meant 
 nothing more than different degrees of the same thing, and not the 
 absolute presence or absence of a specific infection. Again, several 
 different diseases or infections, some borne by different carriers, may 
 be confused under the term 'souring.' Many figs in an early stage 
 of spoilage or with slight indications of deterioration other than 
 endosepsis have been examined in which no indication of Carpophilus 
 or Drosophila could be found. This has been true even in the case 
 of whole orchards where there has been a large percentage of bad 
 figs and no beetles were observed. The commercial test-grading of 
 Adriatic figs from such an orchard, as given in table 4, is typical of 
 this. No Carpophilus beetles were found in this orchard at the time 
 when the samples were taken, but less than half the figs were free 
 from visible indications of fungus infection. 
 
 TABLE 4 
 
 Grading 
 
 of Dried Adriatic Figs from an Orchard in which 
 Fruit Beetles Were Found 
 
 No Dried 
 
 
 Good 
 
 Passable 
 
 Bad 
 
 Total 
 
 Number of figs 
 
 746 
 
 38.8 
 
 433 
 22 5 
 
 745 
 38.7 
 
 1,924 
 
 Per cent 
 
 100 
 
 
 
 The bad figs in this orchard were of a type variously classed as sour 
 or moldy by growers and buyers, but it is impossible to identify the 
 trouble specifically. Many of them showed visible mold or were 
 affected with a deteriorated condition which is sometimes referred to 
 as 'dry rot.' 
 
 Another similar case is presented by a condition which occurs 
 abundantly in Calimyrnas and probably also in Adriatics, in many 
 ' dried figs which appear entirely normal on the outside and pass as 
 good figs. This is a slight dryness and 'seediness' of the meat accom- 
 panied by a faintly sour or disagreeable odor. It is only a question 
 
Bul. 506] 
 
 Fruit Spoilage Diseases op Figs 
 
 31 
 
 Fig. 20. — Dried Calimyrna figs of practically normal appearance but internally 
 slightly affected with 'dry rot. ' (From Hilgardia, Vol. 2, No. 7.) 
 
32 
 
 University of California — Experiment Station 
 
 of degree between figs of this sort and those which are entirely bad 
 and contain nothing but dry seeds. Often there is a large percentage 
 of these which pass commercial grading and are only very slightly 
 'off' in texture and flavor and show no evidence of having harbored 
 insects. It is a common idea that figs like these gradually deteriorate 
 in storage by a slow breaking-down or dry rot of the pulp and change 
 in flavor. Figures 20 and 21 show the external and internal appear- 
 ance of such figs. These pictures are from Caldis' paper on endosepsis 
 and are supposed to represent figs slightly affected with that disease. 
 There is some doubt, however, whether all such figs are thus affected, 
 or if so, whether the endosepsis fungus is the cause of the gradual 
 deterioration of the dried fruit. The evidence shows that this fungus 
 does not persist in dried figs but dies out when they beome thoroughly 
 desiccated. 
 
 TABLE 5 
 Kesults of Cultures from Dried Calimyrna Figs 
 
 Number of 
 figs 
 
 Number of 
 cultures 
 
 Commercial 
 quality 
 
 Actual condition 
 
 Results of 
 cultures 
 
 5 
 2 
 1 
 
 1 
 
 1 
 
 5 
 4 
 1 
 
 2 
 
 2 
 
 Passable 
 Passable 
 Passable 
 Passable 
 Passable 
 
 Sound but slightly bad odor 
 
 Sound but slightly bad odor 
 
 Sound but slightly bad odor 
 
 Perfect appearance, very slight sour odor 
 
 A perfect fig in appearance, odor and flavor 
 
 Yeast in all 
 Yeast in all 
 Yeast 
 
 Yeast in both 
 Yeast in both 
 
 Bearing on this point, table 5 gives the result of culture tests 
 from sound-appearing, freshly dried, commercially passable Calimyrna 
 figs. These were all of perfectly normal external appearance with no 
 visible trace of insect infestation. The first three lots had a very dry 
 seedy look on the inside and a slight but distinct sour, disagreeable 
 odor. The fourth was a large fine fig of perfect appearance but with 
 a very slightly peculiar odor, while the fifth appeared to be an abso- 
 lutely perfect fig in every way. Where two cultures were made from 
 a fig, one was from the flesh just beneath the eye and the other from 
 a point in the flesh near the stem end. The cultures were made on 
 potato-dextrose agar. The yeast obtained was in every case a small 
 round, white form appearing identical with Caldis' yeast E. 
 
 In studying this matter further another set of cultures was made 
 as follows: 
 
 From a lot of dried Calimyrna figs there was selected (1) 10 of 
 the most perfect in color, texture, odor, and taste; (2) 10 of the 
 commercially passable type just mentioned above, showing good color, 
 almost perfect texture (slight seediness), but a faint trace of sour 
 
Bul. 506] 
 
 Fruit Spoilage Diseases op Figs 
 
 33 
 
 Fig. 21. — Interior of dried figs shown in figure 20, affected with 'dry rot.' 
 The pulp is dry and seedy and has a peculiar flavor. In such figs there is no 
 sign of wet, gassy fermentation or of the dried fruit beetle. Cultures yield a 
 small, round, white yeast. (From Hilgardia, Vol. 2, No. 7.) 
 
34 
 
 University of California — Experiment Station 
 
 odor; (3) 10 worthless culls, showing pronounced pink end and 
 internal browning and characteristic odor of endosepis like the figs 
 in figure 33. All had been in a warm room about a month longer than 
 those in the last lot and were rather overdry. 
 
 The endosepsis fungus, Fusarium moniliforme, was not found in 
 any of the cultures. As the figs in lot 3 were typically affected with 
 this disease it would appear that this fungus dies out rather quickly 
 in the dried fig. Seven of the perfect figs in lot 1, and four of the 
 slightly sour ones in lot 2 gave sterile cultures, indicating that either 
 they had never been infected or the organisms had died. The fact 
 that even among the bad figs in lot 3, two gave no growth in culture 
 indicates that sterility in the dried state is not a safe criterion of the 
 original condition of the fig. 
 
 TABLE 6 
 
 Results of Cultures from Dried Calimyrna Figs 
 
 Number of 
 figs 
 
 Number of 
 cultures 
 
 Commercial 
 quality 
 
 Actual condition 
 
 Results of cultures 
 
 10 
 
 10 
 
 Passable 
 
 Perfect 
 
 1 dark mold, 1 yeast, 1 red bac- 
 terium, 7 clear 
 
 10 
 
 10 
 
 Passable 
 
 Perfect appearance, very 
 slight sour odor 
 
 1 Aspergillus niger, 5 mold or yeast, 
 4 clear 
 
 10 
 
 10 
 
 Culls 
 
 Typical endosepsis 
 
 1 Aspergillus niger, 5 yeast, 2 mold, 
 2 clear 
 
 Considering all these facts concerning the presence of micro- 
 organisms in many dried figs where there is no evidence of the Carpo- 
 philus beetle or other known insects, it appears that there may still 
 be an open question of fundamental importance concerning the mode 
 of infection. There is the possibility on the one hand that practically 
 all figs become unavoidably infected with air-borne microorganisms 
 during the ripening period. This has been suggested by Coit in the 
 quotation on page 22. In contrast to this is the conclusion reached 
 by Pierce (1893), Phillips, Smith, and Smith (1925), and Caldis 
 (1930), that infection is limited almost entirely to insect transmission. 
 If this idea is correct then it would seem important to look further 
 than Carpophihis and DrosophUa for such carriers. 
 
 During the progress of these investigations a continuous search 
 has been made for insects of possible importance as agents of disease 
 transmission. Numerous miscellaneous species of Hemiptera, Coleop- 
 tera, and other orders may be disregarded so far as any major signifi- 
 cance is concerned. It seems safe to conclude that no insect of a size 
 readily visible to the naked eye has been overlooked unless it be one 
 of peculiarly obscure habits. 
 
Bitl.506] Fruit Spoilage Diseases of Figs 35 
 
 Thrips. — Caldis (1927, p. 319) made the following' observations on 
 caprifigs: "The larva of an unidentified species of thrips may later 
 enter the cavity [after the eye opens] . Plates were poured repeatedly 
 from blanks and edible figs in order to determine the presence of the 
 thrips larva and its effect on the flora of the fig. Of 95 uncaprified 
 figs examined, the larva was found only in two and the flora of such 
 figs was never found to parallel the flora of caprified figs. Most of the 
 figs were sterile. Occasionally several types of green fungi that bear 
 no relation to the disease [endosepsis] were obtained.' In consider- 
 able more, unpublished work, Caldis found thrips more or less 
 common in figs from certain localities and especially in caprifig blanks 
 (uncaprified), and concluded that they might be the carriers of certain 
 molds and yeasts. Since parthenocarpic uncaprified figs were never 
 observed by him to be affected with endosepsis, he did not consider 
 thrips as carriers of this disease. 
 
 In our own work considerable attention has been paid to this 
 
 matter, since thrips have at times been found abundantly in figs, 
 
 passing in and out of the fruit freely. No one species was exclusively 
 
 concerned but several have been found, mostly forms common to< 
 
 various other plants. The following is quoted from an article by 
 
 Hansen (1929) : 
 
 In May, 1928, the writer collected several thousand uncaprified, hard green 
 figs of four varieties: Calimyrna, Adriatic, Kadota, and Mission, from various 
 parts of California. These figs were cut into halves and examined with a 
 hand lens for evidence of insect invasion, mutilated and discolored floral parts, 
 insect excreta, or the insects themselves. Slightly in excess of 20 per cent of 
 the figs examined were found to be infested with thrips, specimens of which 
 were identified by Mr. Dudley Moulton of San Francisco as Thrips tabaci Lindl. 
 and FranMiniella sp., probably F. californicus Moulton. 
 
 In 1929 species of thrips were found in figs as follows : Frank- 
 liniella tritici (Fitch) and F. tritici var. californicus (Moulton) at 
 Davis, Loomis, Orosi, Sacramento, and Fresno, and Thrips bremneri 
 (Moulton), Liothrips ilex (Moulton) at Davis. These were identified 
 by Mr. S. F. Bailey of the Division of Entomology, University of Cali- 
 fornia, During the late summer and fall of 1929 the bean thrips, 
 Heliothrips fasciatus Perg., was very common in figs throughout the 
 San Joaquin Valley and occurred likewise as a serious pest on cotton 
 and other hosts growing close to or in the fig orchards. 
 
 Concerning the cryptogamic flora of thrips-infested figs, Hansen 
 
 in the article just quoted reported as follows: 
 
 The interior of 200 of the figs showing evidence of insect invasion, and 10 
 showing no such evidence, were cultured individually on nutrient media to deter- 
 
36 University of California — Experiment Station 
 
 mine their cryptogamic flora. Each of the 200 thrips-infested figs yielded one or 
 more of the following organisms: various species of bacteria, Bhizopus spp., 
 Aspergillus spp., Penicillium spp., Fusarium spp., Verticillium spp., Spicaria sp., 
 Hormodendrum spp., and a number of yeasts. The 10 figs showing no evidence 
 of insect invasion yielded no cryptogamic flora in culture. The above results 
 show that when green, hard figs are entered by thrips, they become inoculated 
 with organisms capable of producing various decays and fermentations in the 
 ripening fruit. Though the 1928 season was especially favorable for thrips, 
 the comparatively high percentage of green, hard figs found infested would 
 indicate that infection from this source alone is sufficiently great to cause the 
 growers considerable loss. It is also possible that the early start of decay and 
 fermentation in thrips-infested figs, giving rise to odors very attractive to 
 C. hemipterus and D. ampelophila, is partly responsible for the appearance of 
 these insects in the orchards at the time when figs begin to mature. 
 
 Further culturing of thrips taken from figs has repeatedly given 
 the same results, namely, that they carry an abundant flora of yeasts, 
 bacteria, and mold fungi. Figure 22 shows cultures from thrips. In 
 a few instances the endosepsis fungus, Fusarium moniliforme, and 
 the red bacterium which accompanies it so regularly in connection 
 with blastophaga, have been found in such cultures. There is no 
 positive evidence, however, that thrips are of any importance in the 
 transmission of endosepsis, and it may be that in the few cases men- 
 tioned above they picked up the characteristic organism in figs which 
 had previously been infected by blastophaga. 
 
 In the orchard described on page 30, where more than 50 per cent 
 of the figs were moldy or slightly bad, thrips were abundant and no 
 Carpophilus beetles were found. In 1929 a number of cases occurred 
 in the San Joaquin Valley where fig orchards showed abnormally high 
 percentages of moldy or smutty figs with no indications of sufficient 
 infestations of beetles to account for this. In one case in particular 
 sheep were pastured in the orchard and all the bad figs were kept very 
 closely picked up by this means, thus affording little chance for breed- 
 ing of scavenger insects. In this orchard, however, there was an 
 unusually high percentage of moldy figs and thrips were abundant, 
 as was the case in all the other orchards mentioned. The thrips yielded 
 in culture the same flora found in the figs. These and many similar 
 instances point to the importance of knowing more about the role 
 played by thrips in the transmission of fig diseases. 
 
 The Fig Mite (Eriophyes fici Ewing). — This blister mite of almost 
 microscopic size was first discovered by E. H. Smith (Essig and 
 Smith, 1922) in work on fig smut, and has proved to be very common 
 in both capri and edible figs. It was named by Ewing (see Essig, 
 1922) and is described by Essig (1926) as follows: 
 
Bul. 506] 
 
 Fruit Spoilage Diseases of Figs 
 
 37 
 
 Fig. 22. — Cultures of thrips from blank caprifigs, showing variety of molds, 
 yeasts, and bacteria which may be carried into edible figs and cause spoilage. 
 
38 
 
 University of California — Experiment Station 
 
 The fig mite, Eriophyes fici Ewing, is a minute, white, elongated mite which 
 overwinters in the buds and the fruit of the caprifigs and works in the fruit of 
 edible figs during the summer. All the common varieties except the Black 
 Mission were found infested, the mites causing a faint russeting of the interior. 
 As the fruit ripens the mites work out and often concentrate under the scales 
 at the opening. As yet we can attribute no damage to them. They occur in 
 the fig-growing districts of the San Joaquin Valley, California, and must have 
 been introduced from Europe with nursery stock. 
 
 Phillips, Smith, and Smith paid considerable attention to the pos- 
 sible importance of this mite as a carrier of infection in figs. The 
 same statement applies to the work of Caldis and that of the writers. 
 According to unpublished notes of all these investigators the fig mite 
 is not an important carrier of infection. Cultures from figs showing 
 
 \ 
 
 Fig. 23. — Predaceous mites found in mamme figs. A, Sejus pomi 
 Parrott (X 50). B, Unidentified species (X 50). 
 
 the reddish-brown florets which indicate the presence of mites gave 
 no more microorganisms than those which contained no mites. Such 
 figs in fact were usually sterile until entered by other insects. Appar- 
 ently the life history of this mite is such as to render improbable its 
 carrying pathogenic organisms into the figs. 
 
 Predaceous Mites in Figs. — Figure 23 shows two mites which, with 
 still a third species, have been found in caprifigs in considerable 
 abundance. Specimens of the one marked A have been sent to Mr. 
 H. E. Ewing, who has provisionally identified it as Sejus pomi Parrott 
 (Parrott et at., 1906, and Ewing, 1914). The other two species have 
 not yet been identified. 
 
 The comparative abundance of thrips and mites in mamme figs is 
 shown in table 7. 
 
 Table 8 shows further results of examining mamme figs for insects. 
 
Bul. 506] 
 
 Fruit Spoilage Diseases of Figs 
 
 39 
 
 TABLE 7 
 Hand Lens Examination of Mamme Figs for Insects, January, 1930 
 
 Fig 
 
 No. 
 
 Thrips 
 
 Preda- 
 ceous 
 mites 
 
 Eriophyes 
 fici* 
 
 Fig 
 No. 
 
 Thrips 
 
 Preda- 
 ceous 
 mites 
 
 Eriophyes 
 fici* 
 
 Fig 
 No. 
 
 Thrips 
 
 Preda- 
 ceous 
 mites 
 
 Eriophyes 
 fici* 
 
 1 
 
 4 
 
 3 
 
 + 
 
 21 
 
 
 
 
 
 
 
 41 
 
 
 
 
 
 + 
 
 2 
 
 
 
 1 
 
 + 
 
 22 
 
 
 
 
 
 + 
 
 42 
 
 1 
 
 
 
 
 
 3 
 
 
 
 
 
 + 
 
 23 
 
 
 
 1 
 
 + 
 
 43 
 
 
 
 
 
 + 
 
 4 
 
 
 
 
 
 + 
 
 24 
 
 
 
 
 
 
 
 44 
 
 
 
 
 
 
 
 5 
 
 
 
 2 
 
 + 
 
 25 
 
 
 
 
 
 + 
 
 45 
 
 
 
 
 
 + 
 
 6 
 
 
 
 
 
 
 
 26 
 
 
 
 
 
 
 
 46 
 
 
 
 1 
 
 + 
 
 7 
 
 
 
 
 
 
 
 27 
 
 
 
 2 
 
 + 
 
 47 
 
 
 
 1 
 
 + 
 
 8 
 
 
 
 
 
 + 
 
 28 
 
 
 
 1 
 
 + 
 
 48 
 
 1 
 
 
 
 
 
 9 
 
 
 
 
 
 + 
 
 29 
 
 1 
 
 
 
 
 
 49 
 
 
 
 
 
 
 
 10 
 
 
 
 
 
 + 
 
 30 
 
 
 
 1 
 
 + 
 
 50 
 
 
 
 
 
 
 
 11 
 
 
 
 
 
 + 
 
 31 
 
 
 
 2 
 
 + 
 
 51 
 
 
 
 
 
 + 
 
 12 
 
 
 
 
 
 
 
 32 
 
 2 
 
 
 
 
 
 52 
 
 
 
 2 
 
 + 
 
 13 
 
 
 
 
 
 
 
 33 
 
 
 
 
 
 + 
 
 53 
 
 
 
 
 
 + 
 
 14 
 
 
 
 
 
 + 
 
 34 
 
 
 
 
 
 + 
 
 54 
 
 
 
 
 
 
 
 15 
 
 1 
 
 
 
 + 
 
 35 
 
 
 
 1 
 
 + 
 
 55 
 
 
 
 
 
 + 
 
 16 
 
 
 
 
 
 + 
 
 36 
 
 
 
 2 
 
 + 
 
 56 
 
 4 
 
 1 
 
 + 
 
 17 
 
 1 
 
 1 
 
 + 
 
 37 
 
 
 
 
 
 
 
 57 
 
 
 
 
 
 
 
 18 
 
 
 
 
 
 
 
 38 
 
 
 
 
 
 
 
 58 
 
 
 
 1 
 
 + 
 
 19 
 
 
 
 
 
 + 
 
 39 
 
 
 
 
 
 
 
 59 
 
 
 
 
 
 + 
 
 20 
 
 2 
 
 1 
 
 + 
 
 40 
 
 
 
 
 
 + 
 
 
 
 
 
 -f- = present. 
 
 TABLE 8 
 
 Insect Population of Mamme Figs, January-February, 1930, Showing 
 Number and Percentage of Figs Infested with Each 
 
 
 Thrips 
 
 Predaceous mites 
 
 Fig 
 
 mite 
 
 No insects 
 
 Total 
 
 Locality 
 
 Num- 
 ber 
 
 Per 
 cent 
 
 Num- 
 ber 
 
 Per 
 
 cent 
 
 Num- 
 ber 
 
 Per 
 
 cent 
 
 Num- 
 ber 
 
 Per 
 
 cent 
 
 Num- 
 ber 
 
 Per 
 cent 
 
 Loomis 
 
 4 
 
 28 
 4 
 
 
 21 
 
 1.9 
 5.5 
 4 
 
 
 10.7 
 
 29 
 48 
 11 
 6 
 64 
 
 14 1 
 9.4 
 
 11.0 
 9.4 
 
 32.6 
 
 108 
 
 270 
 
 15 
 
 38 
 
 56 
 
 52.4 
 52.8 
 15.0 
 59.4 
 28.5 
 
 65 
 165 
 70 
 20 
 55 
 
 31.6 
 32 3 
 70.0 
 31.2 
 
 28.2 
 
 206 
 511 
 100 
 64 
 196 
 
 100 
 
 Davis 
 
 100 
 
 Sacramento 
 
 Merced 
 
 100 
 100 
 
 Fresno 
 
 190 
 
 
 
 The predaceous mites pass freely from fig" to fig, apparently prey- 
 ing on the fig mite. How abundant they are in edible figs has not yet 
 been determined. That their bodies are contaminated with pathogenic 
 
 organisms is shown in table 9. 
 
40 
 
 University of California — Experiment Station 
 
 TABLE 9 
 Cultures of Predaceous Mites Taken - from Mamme Figs, 1930 
 
 No. of 
 culture 
 
 Fusarium 
 
 monili- 
 
 forme 
 
 Asper- 
 gillus 
 
 Hormo- 
 dendrum 
 
 Bacteria- 
 like fungus 
 
 Yeast-like 
 fungus 
 
 Yeast 
 
 Bacteria 
 
 Spicaria 
 
 1 
 
 
 
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 + 
 
 
 
 
 
 
 
 + 
 
 
 
 SPLITTING 
 
 In much of the writing about fig- diseases the term 'splitting and 
 souring' is used in a manner which assumes a priori that these 
 phenomena are necessarily concomitant and due to a common cause. 
 This is a very natural assumption, since split figs are usually attacked 
 by swarms of scavenger insects and thereby become infected with the 
 usual microorganisms. 
 
 Condit (1918) discusses the behavior of different varieties of figs 
 
 as to splitting and also suggests the possibility of selecting individual 
 
 trees which are free from this trouble. Regarding the cause of 
 
 splitting he makes the following statements (1919) : 
 
 If the water supply is sufficient and regular and atmospheric conditions are 
 favorable, the fig. increases in size gradually and reaches maturity without 
 splitting. Late or irregular irrigation or any condition which brings about an 
 abnormal supply of moisture increases the amount of water in the fruit, the 
 cells swell due to the imbibition of moisture, and fruits that are solid-fleshed 
 split open, since there is no room for inside expansion. Damp, cloudy, or 
 foggy weather, during which time the humidity is high, reduces the transpira- 
 tion from the leaves, and this in turn increases the amount of water in the 
 fruit, resulting in practically the same conditions to cause splitting as have 
 just been described. The humidity increases and the proportion of split figs 
 increases from Merced County north toward the Bay region. 
 
Bul. 506] 
 
 Fruit Spoilage Diseases of Figs 
 
 41 
 
 
 Fig. 24. — Calimyrna figs showing first stages of splitting. Also affected 
 with endosepsis. (From Hilgardia, Vol. 2, No. 7.) 
 
42 University of California — Experiment Station 
 
 Coit (1921) makes the following' statement: "It is evident that 
 splitting is a purely physical phenomenon due to the inherent weakness 
 of the Smyrna, fig and its inability to withstand the turgor arising 
 from excessive sap pressure. High sap pressure in the fig is caused 
 by failure of the leaves to evaporate the water as fast as it is taken 
 in by the roots. In normal weather, splitting occurs at night when 
 low temperatures, high humidity, and lack of sunlight greatly reduces 
 the evaporation from the leaves." No data have been published to 
 support this conclusion, although a considerable amount of evidence 
 was obtained by Coit and J. C. Johnston upon this point. It is borne 
 out by the experiment of Phillips, Smith, and Smith (1925), in which 
 fig trees were enclosed in a cheese-cloth cover (fig. 17), where it is 
 stated that: "A fact of interest was the splitting of a large number 
 of figs under the tent while outside no splitting was noticed in this 
 
 orchard The temperature in the tent was somewhat lower than 
 
 outside and the humidity greater. Condensed moisture on the fruit 
 and foilage-was frequently noticed under the tent." The conclusion 
 from this experiment would be that splitting is governed by atmos- 
 pheric humidity rather than by soil moisture. 
 
 They state further, "The most striking result of this experiment 
 was that no souring occurred in either tent although it was abundant 
 on all the neighboring trees on the outside. ' ' This demonstrates that 
 splitting and souring do not necessarily accompany each other or 
 result primarily from the same cause. 
 
 The universal occurrence of splitting in the Calimyrna crop of 
 Stanislaus County after September 1, 1930, contrasted with the com- 
 parative freedom from this trouble in Merced County, thirty miles 
 south, lends weight to the idea that climatic conditions are responsible 
 for splitting. In both these districts many orchards w T ere compara- 
 tively free from endosepsis and at the time of the examination made 
 in August 27-28, 1930, and referred to on page 70, the figs were 
 nearly 100 per cent sound. A month later practically every ripe fig 
 in the Stanislaus County orchards was in the condition shown in 
 figure 25, whereas in Merced County there was still very little split- 
 ting. Lower temperature and greater humidity in the more northern 
 district seemed to be the most obvious explanation of this difference. 
 
 Splitting is ruinous to figs, both in itself and also on account of 
 the fermentation and molding which are introduced by insects which 
 swarm into the exposed flesh. In certain districts, apparently from 
 climatic reasons, a large proportion of the Calimyrna figs start to 
 split every year about the first of September or the latter part of 
 
Bul. 506] 
 
 Fruit Spoilage Diseases of Figs 
 
 43 
 
 Fig. 25. — Calimyrna figs ruined by splitting. (Upper photo by Condit.) 
 
44 University of California — Experiment Station 
 
 August. This attracts swarms of dried fruit beetles and vinegar flies. 
 Soft, wet decay, fermentation, and souring follow, and for the 
 remainder of the season the figs are a complete loss. No treatment 
 or control method can be conceived which would prevent this if the 
 splitting of the figs is really due to atmospheric humidity. The pro- 
 duction of good figs is physically impossible under such conditions 
 and no reasonable hope can be held out that fig growing (at least of 
 susceptible varieties like the Calimyrna and Adriatic) can ever be 
 made a successful industry. 
 
 MOLD 
 
 A common defect in dried figs is that called mold, where the inside 
 flesh of the fig is more or less completely destroyed and discolored 
 and shows visible fungus growth. Molds of various colors — white, 
 black, green, brown, and yellow — are of common occurrence. That 
 such molds start to develop in figs when they are still on the tree is 
 shown throughout all the work reported on in this publication. The 
 fact that all the fig-entering^ insects {Carpophilus, Drosophila, thrips, 
 mites, etc.) discussed in connection with various diseases carry spores 
 of many different molds (Aspergillus, Hormodendrum, Cladosporium, 
 Rhizopus, etc. ) , as well as those of more specific pathogenes, has been 
 well demonstrated. It therefore seems logical to assume that infec- 
 tion with these molds is brought about by insects. In cases where no 
 dried fruit beetle can be found, it is a general rule that figs with mold 
 (including the black smut, Aspergillus) may be abundant, but the 
 wet, dripping, soft, gassy type of fermentation or souring does not 
 develop. The relation of mold to sunburn will be discussed in the 
 next paragraph. 
 
 SUNBURN 
 
 In the interior valleys figs are often injured by high temperatures, 
 as shown in figure 26. The end or side of the fig is killed and becomes 
 dry and hard. This is a decided injury to the quality of the dried 
 fig. Those which are burned in the end are called 'round heads' 
 because the dry, hard end does not soften in drying but remains 
 round and hard. Those which are so badly burned as to kill practi- 
 cally the whole fig become hollow and dry and are called ' puff balls. ' 
 Beside the direct injury from the dry, dead tissue in sunburned figs, 
 more loss is caused by the fact that a high percentage of them become 
 infected internally with molds, which further lowers the grade. 
 
 Sufficient irrigation offers the only possibility of preventing sun- 
 burn and the mold which follows it. On stunted trees in shallow soil 
 in a hot climate it is unavoidable. 
 
Bul. 506] 
 
 Fruit Spoilage Diseases of Figs 
 
 45 
 
 Fig. 26. — Figs injured by sunburn, caused by high temperature and drought. 
 This injures the figs and also causes them to mold on the inside. 
 
46 
 
 University of California — Experiment Station 
 
 a 
 
 -y^wfff- ~^w^ 
 
 B 
 
 ■ 
 
 Fig. 27. — Fig smut. A, Interior, mature figs. B, Exterior fresh figs on tree. 
 
 (From Bulletin 387.) 
 
Bui* 506] 
 
 Fruit Spoilage Diseases of Figs 
 
 47 
 
 SMUT 
 
 The so-called 'fig smut' is a characteristic infection with one of 
 the many molds which infest the ripening fig fruit, This is the 
 common black fungus, Aspergillus niger v. Tieg. (figures 28, 29). The 
 disease was described in Europe in 1867 (Reichardt) and in Cali- 
 fornia in 1918 (Hodgson). Phillips, Smith, and Smith (1925) who 
 investigated the disease thoroughly, describe it as follows : 
 
 Fig. 28. 
 
 -Typical spore head of the smut fungus, Aspergillus 
 (much enlarged). (From Bulletin 387.) 
 
 Typical smut in dried figs occurs as a black, powdery mass in the pulp of 
 the fruit [fig. 27]. This mass is composed of fungus spores. On squeezing 
 such fruits the spores shoot out for a considerable distance from the eye in a 
 black cloud, while fruits less affected show dark or yellowish spots in the pulp 
 with no spores. The skin of many of the badly smutted figs has a dark, trans- 
 lucent appearance by which they are easily picked out, but others, especially 
 those with pulp only slightly affected, show no external evidence of disease, 
 and so reach the market. It is only on tearing open such figs that the smut is 
 discovered. Tests have shown that smutty figs are not injurious when eaten, 
 but the appearance of such figs is disgusting, and the finding of one in a 
 package is often enough to cause the whole lot to be thrown away and the 
 
48 
 
 University of California — Experiment Station 
 
 purchaser to hesitate before again buying California dried figs. The discovery 
 of a smutty fig in the preserved, fresh fruit by cutting into it with a spoon 
 and seeing the inky contents run out into the clear syrup, is even more dis- 
 gusting. This has a serious effect on consumption, although the number of 
 smutty figs occurring either in packages of the dried fruit or in the preserved 
 products is extremely small and the actual loss of material is insignificant. 
 
 ^m>' 
 
 Fig. 29. — Cultures of fig smut fungus, made from pulp of figs of type 5 
 (natural size). (From bulletin 387.) 
 
 Phillips, Smith, and Smith showed that infection occurs while the 
 figs are still on the tree but not until the eye opens at about stages 4-6 
 (see figs. 3, 4, 5). Previous to this stage they found the interior of 
 uncaprified figs to be sterile. These investigators believed that the 
 infection is spread largely by the Carpophilus beetle, which they found 
 breeds commonly in the fig districts on all sorts of decayed vegetable 
 matter (see fig. 18). The specific fungus concerned was found to be 
 abundant on such material and also on the bodies of the insects, both 
 before and after they entered the figs (fig. 19). It was therefore con- 
 cluded that the control of smut would depend largely upon sanitary 
 measures to eradicate the breeding material of the beetle. 
 
Bul. 506] 
 
 Fruit Spoilage Diseases of Figs 
 
 49 
 
 The more recent work on souring- relative to the thrips problem 
 has shown that this insect is also a frequent carrier of smut spores 
 and may be an important agent in transmitting this disease. 
 
 Fig. 30. — 'Mildew' or 'black spot' of the Kadota fig, a fungus infection 
 which develops after early fall rains and spoils the fruit for canning. 
 
 SURFACE SPOTTING OF FIGS 
 
 Figure 30 shows the so-called 'mildew' or 'black spot' of the 
 Kadota fig, which sometimes disfigures a considerable amount of fruit 
 and spoils it for canning purposes. This condition develops after 
 summer rains or periods of high humidity which sometimes occur in 
 
50 University of California — Experiment Station 
 
 August or September in the San Joaquin Valley. If there is a good 
 deal of moisture, considerable spotting may develop on the figs while 
 they are still on the tree. Besides this, much fruit becomes affected 
 while in boxes in transit to the cannery. At certain times during the 
 season almost all figs of the white varieties will develop this spotting 
 if they are confined in a moist chamber. 
 
 Cultures of a fungus, a species of Alternaria, have been obtained 
 from affected figs and typical spots have been produced by inoculating 
 Kadota figs with this fungus. 
 
 Tov prevent the spotting of the figs while on the tree, spraying with 
 a fungicide immediately after rain would be necessary. Bordeaux 
 mixture could not be used because the dried residue would disfigure 
 the fruit. Sulfur in any form is undesirable because it is liable to 
 affect the cans in which the figs are packed. The so-called ammoniacal 
 copper carbonate spray, which is a clear solution, might be tried, and 
 may be prepared as follows : 
 
 Copper carbonate 6 oz. 
 
 Ammonia 3 pints 
 
 Water 50 gals. 
 
 First dilute the ammonia with about five times its volume of water 
 and dissolve the copper carbonate in this. It is better to leave a little 
 of the carbonate undissolved than to have an excess of ammonia. Then 
 add the remainder of the water. The commercial spray material called 
 Borco may be substituted for this material, being of a similar nature. 
 
 Dense-topped Kadota trees having the fruit covered with a mass 
 of foliage are more likely to develop this trouble, and on such trees it 
 would be difficult and expensive to cover the figs with spray. A 
 change in the system of pruning might be necessary in certain districts 
 if the spotting of the fruit becomes a common thing. To prevent the 
 figs from spotting while in transit to the canned, they should be kept 
 as dry as possible and should not remain in lug boxes any longer than 
 necessary. A process of dipping the figs in a weak fungicidal solution 
 might be developed, but this would complicate handling and add to the 
 expense. Great care would be necessary not to do anything which 
 would interfere with the canning process. 
 
 Figure 31 shows another surface spot which was common in Cali- 
 myrna figs in 1929. This developed where figs were in close contact 
 with one another, growing in clusters. A brown mold, another species 
 of Alternaria or similar fungus, was present in these spots and 
 appeared to be the cause. The injury was superficial, never penetrat- 
 ing through the outer wall of the fig. 
 
Bui,. 506j 
 
 Fruit Spoilage Diseases of Figs 
 
 51 
 
 It is to be hoped that this spot will not develop sufficient importance 
 to require control treatment. 
 
 Fig. 31. — 'Contact spot' of Calimyrna figs, caused by fungus development 
 at points where closely-clustered figs touch each other. 
 
52 University of California — Experiment Station 
 
 ENDOSEPSIS 
 
 During" the earlier work on fig-spoilage diseases by Coit in 1920 
 and Phillips, Smith, and Smith in 1920-22, mention was occasionally 
 made of a 'new' fig- disease affecting the Calimyrna variety. This 
 disease was variously referred to as ' pink rot, ' ' brown rot, ' ' soft rot, ' 
 and * internal rot.' Caldis described it as follows: 
 
 The disease manifests itself internally as soon as the figs begin to ripen. 
 In severe cases, even before the pulp sweetens and just as soon as the stalks 
 and the sepals of the individual florets swell and begin to color, brown streaks 
 may be seen running down the flower stalks almost to the meat. As the fig 
 ripens such streaks develop into spots, yellow-brown in color, and may involve 
 a number of flowers. In most cases these colored spots are first found in the 
 pulp near the eye of the fig, but any other part or parts of the pulp may 
 develop this symptom according to the locus of infection. In very early stages, 
 just as the fig begins to sweeten, these spots stand out very clearly against the 
 bright-colored healthy pulp. [Figure 32] shows six figs, five of which are at 
 the same stage of maturity and alike in external appearance, firm, and bright 
 green, just at the stage when figs are picked for canning or for fresh shipment. 
 From their external appearance all five could be taken for sound ripe figs. 
 Fruit a represents a healthy fig at this stage of maturity. The pulp should be 
 bright amber to pink, with a small amount of sweet juice in the cavity. Fruits 
 &, c, d, and e show the endosepsis symptoms at different stages of development. 
 In fruit & the brown includes almost the entire mass of flowers in the vicinity 
 of the eye, in the third fruit the browning includes three-quarters of the pulp, 
 in the fourth all but few flowers at the stem end are involved, and in the fifth 
 the entire pulp is disintegrated. Such pulp is slightly watery and is easily 
 pulled away from the meat. Until this last stage is reached, and even later, 
 there is almost no external sign of this diseased condition of the pulp. 
 
 When the fig softens and begins to dry, a water-soaking of the skin appears 
 in indefinite areas, mostly around the eye in a circular spot, or extending down 
 the sides to the neck of the fig. This water-soaking gradually assumes a bright 
 pink or purple color and the epidermis of the fig may easily be rubbed off on 
 such water-soaked spots [fig. 24]. The fig may dry in this condition and 
 fruit / in [figure 32] and the fruits in [figure 33] represent such dried figs. 
 These pink spots should not be confused with the pink spots produced by 
 Aspergillus niger van Tiegh., the black-smut organism of the fig, as described 
 by Phillips, Smith, and Smith. In the case of the internal rot the spots are 
 not very wet and the margins are not shrunk and have not the tendency to 
 be easily detached from the rest of the skin as in the black-smut spots. In the 
 internal rot they appear as normal skin except in color. It is not always, 
 however, that such colored spots appear on the decaying figs. Under favorable 
 weather conditions the figs dry before they reach the stage of external symptoms, 
 and undoubtedly even before the entire pulp is decayed. In many cases only 
 a small water-soaked ring appears around the eye and a drop of liquid is 
 exuded, varying in color from clear to caramel. This exudate is never in 
 sufficiently large quantities to drip and soil the foliage or solidify in long 
 hanging drops, as is the case in souring. [Caldis, 1927.] 
 
Bui,. 506] 
 
 Fruit Spoilage Diseases of Figs 
 
 53 
 
 Fig. 32. — Calimyrna figs at stage of maturity ready for picking for fresh 
 shipment or canning, showing progressive internal symptoms of endosepsis. 
 External appearance normal in the first five, a, Normal fig. b, Flowers around 
 the eye diseased, c, Three-fourths of the pulp diseased, d, Seven-eighths of the 
 pulp diseased, e, Entire pulp diseased. /, External symptoms, meat invaded. 
 (From Hilgardia, Vol. 2, No. 7.) 
 
54 
 
 University of California — Experiment Station 
 
 Fig. 33. — Dried Calimyrna figs showing external symptoms of endosepsis. 
 The dark watersoaked spots are pink, red, or purple in color. Notice the small 
 drop of gum at the eye of one fig. (From Hilgardia, Vol. 2, No. 7.) 
 
Bul. 506] 
 
 Fruit Spoilage Diseases of Figs 
 
 55 
 
 Fig. 34. — Fusarium moniliforme var. fici n. var. a, Macroconidia from sporo- 
 dochium on autoclaved cornmeal (X 782). b, Macroconidia from sporodochium 
 on blackberry stem (X 782). c, Conidiophores and microconidia. d, Microconidia. 
 e, Microconidia in chains and loose heads. /, Pseudochlamydospores (X 782). 
 g, Sporodochia on autoclaved cornmeal. (From Hilgardia, Vol. 2, No. 7.) 
 
56 
 
 University of California— Experiment Station 
 
 Fig. 35. — Culture plates showing, A, a section of a plate with insects from 
 disinfected mamme fig, with no fungus growth (the blastophaga on the left 
 shows a slight development of bacteria) ; B and C, the growth of endosepsis 
 fungus from blastophagas from untreated figs. (From Circular 311.) 
 
Bul. 506] 
 
 Fruit Spoilage Diseases of Figs 
 
 57 
 
 Boncquet (1921), in a newspaper article, discussed what, at least 
 in part, was probably this disease and described as its cause a fungus 
 which he calls Cylindrotrichum fici. The meagre description of this 
 fungus suggests that it is the same organism which Caldis later 
 described as Fusarium moniliforme var. fici, and proved to be the 
 cause of endosepsis. 
 
 Fig. 36. — Typical flora of a caprified fig, showing the three characteristic 
 organisms. (From Hilgardia, Vol. 2, No. 7.) 
 
 Caldis (1925, 1927) in 1922, 1923, 1924, and 1925, thoroughly 
 investigated this trouble, naming it endosepsis and establishing the 
 fact that it is caused by the specific fungus just mentioned (fig. 34). 
 He found that this fungus occurs almost universally in caprifigs and 
 is transmitted from fig to fig by the indispensable pollinating insect, 
 blastophaga (fig. 35). The organism first establishes itself on the 
 dead stigmas of the florets, in the pollen of the profichi, and finally 
 fills the caprifigs entirely with a white mold when they are old and 
 spent. He states: 
 
 The fungus overwinters along with the blastophaga in the mamme fig. In 
 April the adult females carry the spores of the fungus into the profichi where they 
 
58 University of California — Experiment Station 
 
 germinate and grow on the stigma of the gall flowers and the body of the dead 
 insect. In June the adult females come out of the profichi carrying spores of 
 the fungus on their bodies. Some of these females enter Calimyrnas and infect 
 them, others enter mammoni caprifigs, where they carry the infection and lay 
 their eggs. The blastophaga coming out of the mammoni transmit the infection 
 to the mamme in September and the cycle is completed. 
 
 Caldis also found two forms of bacteria constantly associated with 
 
 caprified figs and on the bodies of the blastophaga. 
 
 Plate cultures from the pulp of a diseased fig which has not been exposed 
 to the atmosphere always yield a typical growth or rather a group growth, 
 which consists almost exclusively of the fungus mentioned and of. a cream- 
 colored and a bright red bacterium. This association has been found to be 
 remarkably constant. It may be said also that both bacteria have been obtained 
 from figs irrespective of disease symptoms, and in all stages of maturity, but 
 not previous to caprification. 
 
 Figure 36 shows the typical flora of caprified figs and blasto- 
 phaga. 
 
 No pathogenic significance was found to be attached to the bacteria 
 mentioned, but their constant association with the blastophaga and 
 with the interior of caprified figs has been frequently corroborated by 
 the present writers. 
 
 Caldis attempted to find fungus-free individual caprifigs from 
 which clean colonies of blastophaga might be built up, but the latter 
 has never been successfully accomplished. 
 
 Control of Endosepsis by Disinfection of Caprifigs. — Hansen (1927, 
 1928) in 1926 conceived an entirely new idea in the control of endo- 
 sepsis, namely, that of treating the interior of the caprifigs with a 
 fungicide in such a manner as to destroy the fungus on the exposed 
 floral parts and surface tissues without injuring the blastophaga in 
 the galls or destroying the caprifigs themselves. 
 
 Injection Method. — The first work was described (Hansen, 1927, 
 
 p. 199) as follows: 
 
 When the writer took over the control problem in July, 1926, it occurred to 
 him that it might be possible to apply to the interior of the caprifig a fungicide 
 which would be strong enough to kill the fungus without injuring either the 
 fig itself or the insects still in the galls. In order to test out this possibility 
 the following experiment was carried out: A large number of caprifigs 
 (mammoni) were treated internally with the following fungicides: mercuric 
 chloride, 0.05 per cent; formaldehyde, 0.2 per cent; mercurochrome, 0.1 per 
 cent; Semesan, 0.2 per cent; and commercial lime sulfur, 5.0 per cent. Injec- 
 tions were made with a hypodermic syringe through the eye of the fig not less 
 than three weeks after the fig had been caprified so that the insects would be 
 either in the larval or pupal stage and therefore well down in the center of 
 the gall. Treatment with the above-mentioned fungicides had apparently no 
 
Bitl. 506] Fruit Spoilage Diseases of Figs 59 
 
 adverse effect on either the figs or the blastophaga, as the figs matured normally 
 and the insects emerged at the proper time. 
 
 Treated figs were removed from the trees and cultured on nutrient media 
 at intervals of three weeks after treatment up to the time of maturity when 
 the emerging blastophaga were caught and also cultured. An equal number 
 of untreated figs and blastophaga from untreated figs were cultured as checks. 
 The following results were obtained: All the treated figs and the insects 
 emerged from them were found to be free from Fusarium moniliforme Sheld. 
 var. fid Cald. ; all the untreated figs and the insects emerged from them were 
 found to be 100 per cent infected with the fungus. 
 
 Dipping Method. — Further experience suggested a modification of 
 this method (Hansen, 1928). 
 
 Notwithstanding the effectiveness of the injection method, it was 
 found to have some very serious limitations that make it undesirable 
 for use on a large scale. The operation requires considerable skill and 
 very great care, making it a slow and tedious affair. Because of internal 
 structure (solid center) most varieties of caprifigs cannot be treated 
 by this method. To be effective, injection must be done over a short 
 period of time, preferably within six or eight week after the figs have 
 been cap rifled, and finally, when injecting a large number of figs on 
 a tree, a few might easily be overlooked and left untreated to start 
 infection over again. 
 
 On account of these difficulties the dipping method was developed 
 in 1927. This consisted in gathering the mamme figs from the trees 
 when they were mature and ready to discharge the blastophaga, split- 
 ting them in two, and dipping them in the fungicide. Although com- 
 plete sterilization could not be effected in this manner, the develop- 
 ment of the endosepsis fungus could be retarded for several days, 
 giving time to hang the pieces of mamme figs in the trees and allow 
 the blastophaga to function without contamination. This method was 
 tried on an orchard scale and proved successful and practical. 
 
 Methods Used in State-wide Endosepsis Clean-up of 1928. — In 
 1928, on account of the almost total loss from endosepsis of the Cali- 
 myrna crop of 1927 and the promising results of the control method 
 just described, a demand arose for concerted action to attempt to 
 control this disease simultaneously over the whole interior valley, or 
 in fact in all parts of California where Calimyrna figs are grown. 
 This effort had the almost unanimous support of the fig industry and 
 was shared by the California Peach and Fig Growers, Inc., the Cali- 
 fornia Dried Fruit Association, State Department of Agriculture, 
 County Horticultural Commissioners, Agricultural Extension Service, 
 and the Agricultural Experiment Station. 
 
60 
 
 University of California — Experiment Station 
 
 In order to accomplish the desired result of state-wide control it 
 appeared, in light of the difficulties already mentioned, that neither 
 the injection nor the clipping method could hope to succeed; the 
 former on account of the slow and laborious nature of the operation ; 
 the latter because of the impossibility of leaving all the mamme figs 
 on the trees until the insects begin to emerge and the uncertainty of 
 getting the dipped caprifigs removed from the trees at the end of a 
 four-day period. 
 
 Fig. 37. — Dipping split mamme figs for use in insectary method of obtaining 
 clean blastopliagas. Insectary containing incubators in the background. Photo 
 by Clifford Clower, California State Department of Agriculture. 
 
 During the campaign of 1928 practically all the mamme figs in 
 California, amounting to about 60 tons, were removed from the trees 
 during the months of February and March under the supervision of 
 the various County Horticultural Commissioners. These figs were 
 shipped to a central insectary at Fresno and placed in storage in a 
 cool warehouse in fruit lug boxes. Considerable difficulty was experi- 
 enced in keeping these figs in good condition on account of mold and 
 decay which attacked them very seriously. This was found to be pre- 
 
Bul. 506] 
 
 Fruit Spoilage Diseases op Figs 
 
 61 
 
 ventable to a large extent by sorting the mamme figs very carefully 
 before storage and removing- all bruised, defective, or partly frozen 
 ones. It has long been known that mamme figs may be gathered even 
 as early as December and stored through the winter without destroy- 
 ing the insects or seriously hindering their normal development. The 
 principal problem involved is that of the proper degree of humidity 
 and temperature in storage to preserve the insects and figs in good 
 condition and keep the latter from rotting. 
 
 Fig. 38. — Interior of insectary, showing steam-heated incubators in which 
 the mamme figs were placed after splitting and dipping, with glass tubes in 
 which blastophagas were collected. Photo by Clifford Clower, California State 
 Department of Agriculture. 
 
 The figs were removed from storage as wanted and preheated in a 
 small room for 24 hours at 85° F to stimulate the insects ; they were 
 then split and dipped for 15 minutes in 0.2 per cent Semesan (fig. 37), 
 then placed in steam-heated incubators from which the blastophaga 
 emerged into 1 by 8 inch glass test tubes (fig. 38). In this state 
 (fig. 39) the insects were distributed to the orchardists, using care to 
 keep the tubes cool and dark. When used for caprifying the profichi, 
 the tubes were opened and hung on the branches or the insects were 
 shaken out into shallow fruit baskets placed in the caprifig trees. 
 More than 100,000 tubes containing 500 blastophaga each were dis- 
 tributed in 1928. 
 
62 University of California — Experiment Station 
 
 This method had the advantage of permitting' scientific exactitude 
 in testing the blastophaga for the endosepsis fungus and keeping the 
 mamme figs, with all danger of reinfection, entirely away from the 
 trees. It had the disadvantage that when caprification was practiced 
 these delicate, sensitive insects had to be put out into the open without 
 the protection afforded by the cavity of the fig during the normal 
 automatic adjustment between climatic conditions, the maturity and 
 emergence of the blastophaga, and the receptivity of the profichi. 
 Thus it frequently happened that after the insects were liberated, 
 weather conditions became unfavorable for them to function. More 
 knowledge of the technique of handling the blastophaga to keep them 
 in a vigorous condition would improve this situation. 
 
 Shortage of Crop. — The most outstanding feature of the whole 
 situation in 1928 and the one which had probably the most immediate 
 influence upon the grower was the fact that the final number of tubes 
 ordered was from five to ten times greater than the original estimates. 
 This resulted in a rushing and upsetting of the plan and schedule of 
 the campaign and a large deficiency in filling the total orders. This 
 again resulted in a short crop of profichi, a short crop of Calimyrnas, 
 and disappointment to many growers. Regrettable as this was, it was 
 not in itself a serious factor in the broad question of finding a perma- 
 nent method of handling the fig situation, particularly in view of the 
 fact that in many cases the total crop of good figs was greater in 1928 
 than it had been in 1927. 
 
 Going over the campaign in detail, the facts given in the following 
 paragraphs stand out as having affected the final result : 
 
 Removal of Mamme Figs. — It is almost unbelievably difficult to 
 remove all the mamme figs from a tree. This being true even under 
 the most favorable circumstances, it is easy to understand what hap- 
 pened in cases where the owner was rather indifferent or where he 
 was actually hostile and opposed to the removal of his mamme figs. 
 Comparatively few trees were stripped of absolutely every mamme 
 fig, even where the intentions were of the best. Many more were left 
 through carelessness, while in the orchards of 'conscientious objectors' 
 it is even possible that some trees were not stripped at all or very 
 indifferently. 
 
 Disinfection of Mamme Figs. — Numerous tests showed that when 
 carefully and properly performed, the dipping process retarded the 
 fungus in the mamme figs so that the blastophaga emerged in a clean 
 condition. It would be rash to say that this was 100 per cent perfect 
 in every batch treated during the height of the rush and confusion of 
 the campaign. 
 
Bul. 506] 
 
 Fruit Spoilage Diseases of Figs 
 
 63 
 
 
 I , t0 \ 
 
 \ ft W . 
 
 
 § ' 
 
 ^ 
 
 Pig. 39.— Clean blastophaga in glass vials as used in insectary method 
 to capnfy profichi crop. (From Circular 311.) 
 
64 University of California — Experiment Station 
 
 Caprification of the Profichi. — Much variation in results developed 
 from varying- conditions at the time the insects were put out in the 
 trees to caprify the profichi crop. In some cases a normal number of 
 figs was set by the number of insects contained in a tube. Again 
 the condition of the weather or that of the insects or that of the 
 profichi was such that not much caprification was obtained from the 
 tubed insects. Meantime the condition discussed above existed, namely, 
 that some mamme figs were lef fr on many trees. It was impossible in 
 a great many cases to say positively that certain trees were caprified 
 entirely with tubes, even though tubes of insects were placed in the 
 trees. More profichi may have been set by the insects from even a 
 very few mamme figs left in the tree than those from the limited 
 number of tubes which were used. Doubtless many profichi, also, 
 which had been caprified by tubed insects, were entered and infected 
 by blastophaga from untreated mamme figs. It was rumored that 
 some growers purposely left a considerable number of mamme figs on 
 their trees and that others picked the mammes but did not send them 
 to the insectary. These were stored at home and were later used 
 without disinfection, or, in a few cases, the owner dipped them himself, 
 apparently with considerable success. Some growers conscientiously 
 removed their mamme figs and depended solely upon the tubes of 
 blastophaga which were regularly allotted to them. A few were able 
 to obtain extra tubes and correspondingly more insects. Some used 
 mamme figs which had not been disinfected. Thus the actual condition 
 of the profichi was more or less uncertain in most cases. 
 
 Caprification of Edible Crop. — The profichi were used in the cus- 
 tomary manner except that where a shortage existed they were in 
 some cases distributed more sparsely than usual. In other instances 
 they were concentrated on a limited number of trees and no attempt 
 was made to caprify the whole orchard. The setting of the edible crop 
 was governed mainly by the number of profichi used, which varied 
 greatly. Some growers used only the profichi which resulted from the 
 number of tubes of blastophaga which they were able to obtain. This, 
 in practically every case, was much less than the amount ordinarily 
 used. Many bought extra profichi, some claiming to have been 
 caprified by clean insects, some frankly 'bootleg' of untreated or 
 unknown origin. 
 
 Results of the Campaign of 1928. — Only a very general statement 
 can be made on the results of the season's campaign, on account of 
 the uncertainties just described. In only a very few cases could one 
 determine with absolute certainty what the condition of the profichi 
 
Bul, 506] Fruit Spoilage Diseases of Figs 65 
 
 was, and without such information it is useless to draw any positive 
 conclusions from the condition of the Calimyrnas. The 'bootleg' 
 profichi, those caprified by tube insects, and those from mamme figs 
 left on the trees, were all mixed together in many orchards. According 
 to fairly extensive observations, in cases where all the mamme figs had 
 been removed and all the profichi caprified with insectary blastophaga, 
 the grower obtained from 5 to 15 per cent of a normal crop of Cali- 
 myrnas. Where extra profichi were obtained, the size of the crop 
 increased accordingly up to a point in a few orchards of practically 
 a normal yield. As a general rule any orchard which bore much over 
 15 per cent of a normal crop could safely be assumed to have been 
 caprified with extra (and usually untreated) profichi figs. 
 
 The quality of Calimyrnas in practically every case varied directly 
 with the condition of the profichi according to their source, so far as 
 could be determined. In general, the Calimyrnas were better in 1928 
 than in 1927 or 1926 regardless of the profichi used. This may have 
 been due in part to light caprification, and in part to a season less 
 favorable to endosepsis. Beyond this, however, it was plainly apparent 
 and generally admitted that the light crops which were known to have 
 come almost entirely from tube insects were practically 100 per cent 
 clean of endosepsis, while in the few normal Calimyrna, crops which 
 had been obtained by the use of ' bootleg ' profichi or those which came 
 from trees that were not completely stripped of the mamme crop a 
 large amount of rot developed. Certainly the districts or orchards 
 where the clean-up was followed most conscientiously had the cleanest 
 Calimyrna figs they had had for many years, and a great deal more 
 rot developed where the campaign was opposed. 
 
 Endosepsis Clean-up of 1929. — At the end of the season of 1928 
 the sentiment prevailing among the fig growers of the San Joaquin 
 Valley was almost 100 per cent in favor of the idea that control of 
 endosepsis depends upon the use of profichi which have been freed 
 of the causative fungus. The idea of an enforced clean-up, however, 
 especially by a method dependent upon sending the caprifigs away 
 for treatment to a more or less distant point, had many opponents. 
 The use of the dipping method by individual growers as practiced in 
 1927 had from the first attained much popularity. Its one serious 
 drawback had been the necessity of allowing the mamme figs to remain 
 on the trees until the blastophaga began to emerge, thus incurring 
 considerable danger of infection of the profichi by early-escaping 
 insects. The discovery in connection with the insectary method that 
 the mamme figs could be gathered early and kept in storage for a 
 
66 
 
 University of California — Experiment Station 
 
 considerable time, and the insects then be caused to emerge at any 
 desired time by the application of heat, removed this objection and 
 greatly increased the possibilities of the general voluntary use of the 
 dipping method by individual growers. 
 
 TABLE 10 
 
 Cultures of 1929 Mamme Figs to Determine Percentage Infectej) 
 
 with endosepsis 
 
 One sample (usually 10 figs) represents one tree. 
 
 County 
 
 Stanislaus: 
 Hansen* 
 
 Merced: 
 
 Hansen 
 
 Scottf 
 
 Total 
 
 Madera: 
 Hansen v 
 
 Fresno: 
 
 Hansen 
 
 Scott 
 
 Total 
 
 Tulare: 
 
 Hansen 
 
 Scott 
 
 Total 
 
 Various Counties: 
 
 Hansen 
 
 Scott 
 
 Total 
 
 Entire State: 
 
 Hansen 
 
 Scott 
 
 Total 
 
 Number of 
 figs cultured 
 
 421 
 
 1,500 
 
 439 
 
 1,939 
 
 50 
 
 1,546 
 
 417 
 
 1,963 
 
 260 
 309 
 569 
 
 70 
 15 
 85 
 
 3,847 
 1,180 
 5,027 
 
 Number of 
 samples 
 
 36 
 
 192 
 
 44 
 
 236 
 
 157 
 
 7 
 164 
 
 24 
 24 
 
 48 
 
 417 
 
 76 
 
 493 
 
 Number of 
 figs infected 
 
 153 
 
 341 
 
 96 
 
 437 
 
 181 
 
 42 
 
 223 
 
 17 
 28 
 45 
 
 19 
 
 1 
 
 20 
 
 718 
 167 
 885 
 
 Per cent 
 figs infected 
 
 36.34 
 
 22.73 
 21.80 
 22 50 
 
 14 00 
 
 13 26 
 
 86 
 
 10.07 
 
 4 
 
 11.31 
 
 90 
 
 6.54J 
 
 9 
 
 9.06 
 
 16 
 
 7.90 
 
 25 
 
 27.14 
 
 5 
 
 6.60 
 
 1 
 
 23.53 
 
 6 
 
 18.66 
 
 255 
 
 14.15 
 
 56 
 
 17.60 
 
 311 
 
 Number of 
 samples 
 infected 
 
 34 
 
 118 
 
 35 
 
 153 
 
 * Experiment Station. 
 
 t State Department of Agriculture. 
 
 X Most of these figs were from the caprifig orchard of the California Peach and Fig Growers, Inc., at 
 East Orosi, where very thorough clean-up was practised in 1928. 
 
 An important factor in the prospective program for 1929 was the 
 question of the condition of the caprifigs in the winter of 1928-29, 
 following the 1928 clean-up. It would seem that some lessening of the 
 amount of endosepsis infection in the caprifigs should have followed 
 that extensive campaign. In order to test this, growers were invited 
 to send samples of mamme figs and profichi during the spring of 1929, 
 either to the Experiment Station or the State Department of Agricul- 
 
Bul. 506] 
 
 Fruit Spoilage Diseases of Figs 
 
 67 
 
 ture, for a culture test to determine the percentage of figs infected. 
 The method adopted was to pick 10 figs from each caprifig tree to be 
 tested. In the laboratory each fig was split open and the interior mass 
 of galls and florets was scooped out with a sterile knife into a sterile 
 
 TABLE 11 
 
 The Flora of Cafrified Male Figs from Commercial Orchards in California 
 During the Years 1922, 1923, 1924, ani> 1925 
 
 
 Number 
 
 of figs 
 examined 
 
 Per cent 
 F. monili- 
 
 forme 
 var. fici 
 
 Per cent 
 
 red 
 bacterium 
 
 Per cent 
 
 white 
 bacterium 
 
 Per cent 
 green 
 fungi 
 
 Per cent 
 
 Torula 
 
 yeast 
 
 Per cent 
 
 sterile 
 
 figs 
 
 Mamme 1922 and 1923: 
 Sacramento Section 
 
 52 
 45 
 22 
 29 
 49 
 24 
 
 221 
 
 63 
 45 
 115 
 46 
 54 
 
 323 
 
 16 
 43 
 47 
 44 
 70 
 
 79 
 
 12 
 
 5 
 
 7 
 
 5 
 
 500 
 64 
 
 30.7 
 35.5 
 54.6 
 31.0 
 32 6 
 41.7 
 
 46 
 51.1 
 40 9 
 52.2 
 46.3 
 
 50 
 69.8 
 
 51 1 
 25.0 
 17.1 
 
 55.6 
 58.3 
 100 
 28.6 
 60 
 
 59.4 
 45.3 
 
 13.4 
 40 
 63.6 
 44.8 
 61.2 
 70.8 
 
 68.3 
 82.1 
 65.2 
 78.2 
 92.5 
 
 43 8 
 67.4 
 80 8 
 432 
 
 41.7 
 20 3 
 
 61.5 
 35.6 
 59 
 34.5 
 28.6 
 62.4 
 
 44.4 
 40 
 18.3 
 21.7 
 
 38.9 
 
 68.7 
 67.4 
 51.0 
 51.0 
 
 100 
 23.4 
 
 2.22 
 4.55 
 3.45 
 18.4 
 4 17 
 
 12.7 
 6.66 
 
 10 4 
 4.35 
 3.70 
 
 25 
 4.25 
 
 11 5 
 
 2 22 
 4.55 
 
 3 45 
 18 18 
 
 12 5 
 8.50 
 11 40 
 
 19 2 
 
 Modesto 
 
 20.0 
 
 Merced 
 
 9 08 
 
 Fresno 
 
 17 2 
 
 Reedley 
 
 2 04 
 
 Tulare 
 
 16 6 
 
 Profichi 1928: 
 Modesto 
 
 4 76 
 
 Merced 
 
 4 45 
 
 Fresno 
 
 13 9 
 
 Reedley 
 
 
 Tulare 
 
 7 41 
 
 Profichi 1924: 
 Modesto 
 
 6 25 
 
 Fresno 
 
 
 Reedley 
 
 
 Tulare 
 
 6 81 
 
 Southern California 
 
 10 00 
 
 Mammoni 1924-' 
 Sacramento 
 
 
 Modesto 
 
 
 Fresno 
 
 
 Reedley 
 
 
 Southern California 
 
 
 Mamme 1924: 
 Sacramento 
 
 
 Modesto 
 
 
 
 
 From: Caldis, Panos D. Etiology and transmission of endosepsis (internal rot) of the fruit of the fig. 
 Hilgardia 2:312. table 4- 1927. 
 
 petri dish. A tube of melted nutrient agar was then poured over the 
 fig tissue and allowed to harden. The plates were then observed for 
 growth of the endosepsis fungus. The cultures were made by Messrs. 
 C. E. Scott of the State Department of Agriculture and H. N. Hansen 
 of the Experiment Station, the former of whom has kindly furnished 
 
68 University of California — Experiment Station 
 
 us his figures for publication in the accompanying- table (table 10). 
 These figs were mostly from trees on which an attempt at clean-up 
 had been made in 1928. Much variation in percentage of infection 
 will be noted, but in general the improvement over conditions existing 
 previous to 1928 (see table 11) is very marked. 
 
 On the basis of this work it was hoped that such testing might 
 make it possible to decide whether a given lot of mamme figs required 
 treatment or might be used without dipping if they showed a low 
 percentage of endosepsis. In practice, however, this did not work out 
 satisfactorily because a high percentage of disease in the Calimyrna 
 crop sometimes developed from a low-testing lot of mamme figs. 
 Apparently the fungus builds up so rapidly in the profichi that an 
 infection of, say, 10 per cent in the mamme may be sufficient to cause 
 a high percentage of loss in the edible crop. It is noticeable, however, 
 in comparing the amount of endosepsis found in 1929 (table 10) with 
 the figures for profichi given by Caldis (table 11) for 1923 and 1924, 
 that the amount of infection had been greatly reduced. 
 
 During February a series of demonstrations of the dipping method 
 was held by the Agricultural Extension Service throughout the San 
 Joaquin Valley. The principal effort at fig improvement in 1929 was 
 made in Merced County. In the other counties only a few individual 
 growers made any effort to treat their caprifigs. In Merced, under the 
 leadership of County Agricultural Commissioner Dooley P. Wheeler 
 and a committee of local growers, a clean-up area was formed includ- 
 ing about 1,500 acres of Calimyrna figs in a territory of four square 
 miles, representing the holdings of thirty growers. In another large 
 similar fig area immediately adjoining no treatment was attempted, 
 thus furnishing a check on the results of the effort. 
 
 The methods adopted varied somewhat in the different portions of 
 the clean-up district or even in the same orchard, so that the results 
 of the season's work cannot be analyzed too critically. In general, 
 however, the mamme figs were removed from the trees as late as 
 possible before any blastophaga emerged, which meant sometime 
 during March. Itwras then necessary to store the figs for a time, which 
 was done in open boxes in a cool, moist room or in some cases buried 
 in sand or sawdust. When the insects were needed for caprifying the 
 profichi crop, many growers made an attempt to preincubate the 
 mamme figs in order to force the emergence of the blastophaga, They 
 were kept, for instance, in a small, warm room like a bathroom for 
 24 hours or in a chicken incubator. The figs were then split into two 
 or four parts and soaked for 10 minutes or longer in Semesan solution, 
 
Bul.506] Fruit Spoilage Diseases of Figs 69 
 
 the strengths used varying from 1 ounce to 8 gallons to 1 ounce to 
 4 gallons. The pieces were then hung in the trees in various con- 
 tainers, left for four days and then removed and either destroyed or 
 dipped and used again. Some lots were dipped and put out a third 
 time, the plan being never to leave them in the trees for more than 
 four days and finally to destroy them. The details as well as the 
 thoroughness of the above described procedure varied considerably in 
 individual cases. 
 
 On account of a shortage of profichi due to severe frost in April, 
 the growers of the Merced County clean-up area purchased the crop 
 of the caprifig orchard belonging to the California Peach and Fig 
 Growers, Inc., situated near East Orosi. This orchard, consisting of 
 about 50 acres of the principal varieties of caprifigs, had been very 
 carefully stripped of the mamme crop in 1928 and recaprified entirely 
 with the inseetary blastophaga in glass tubes. In order to increase 
 the setting of profichi the Merced growers used a considerable quantity 
 of their own mamme figs in the Orosi grove. These were all split and 
 dipped in the usual manner. The mamme crop of the Orosi trees was 
 not gathered and dipped because the tests had shown such a low 
 percentage of endosepsis in them. 
 
 Outside of Merced County the principal efforts made in 1929 to 
 prevent endosepsis by treatment of mamme figs were, so far as known 
 to us, those of several growers in Stanislaus County and a few in 
 Fresno and Tulare counties. Most of the others depended on the low 
 percentage of infection in the mamme crop resulting from the 1928 
 clean-up to carry them through or left the whole matter entirely to 
 chance. 
 
 Results of Endosepsis Control of 1929. — The positive results of the 
 efforts made in 1929 to control endosepsis by the dipping method were 
 in almost every ease pronounced and easily recognized. Late in 
 August a trip was made through the fig districts of the San Joaquin 
 Valley and the Calimyrna figs, which were just beginning to drop, 
 were tested in a number of representative orchards in the following 
 manner: All the figs on the ground under a number of trees were 
 picked up and thrown together in one pile and thoroughly mixed. 
 From these 100 figs were picked out at random. At this time endo- 
 sepsis was the only disease present in most cases and the number of 
 figs in the sample which showed the typical pink ends, brown flesh, 
 and characteristic odor was counted. The following results were 
 obtained : 
 
70 
 
 University of California — Experiment Station 
 
 TABLE 12 
 
 Amount of Endosepsis in Treated and Untreated Calimyrna Fig Orchards, 
 
 August 26-29, 1929 
 
 County 
 
 Orchard 
 
 Mamme figs 
 dipped (?) 
 
 Per cent 
 endosepsis 
 
 / 
 
 A 
 
 Yes 
 
 
 
 
 B 
 
 Yes 
 
 2 
 
 
 C 
 
 Partly 
 
 14 
 
 
 D 
 
 Yes 
 
 
 
 Merced < 
 
 E 
 F 
 
 Yes 
 Yes 
 
 2 
 4 
 
 
 G 
 
 Partly 
 
 8 
 
 
 H 
 
 Partly 
 
 18 
 
 
 I 
 
 No 
 
 32 
 
 > 
 
 J 
 
 No 
 
 40 
 
 f 
 Fresno J 
 
 K 
 L 
 
 Yes 
 No 
 
 
 40 
 
 ( 
 
 M 
 
 No 
 
 60 
 
 f 
 
 N 
 
 No 
 
 60 
 
 Tulare J 
 
 
 P 
 
 No 
 Yes 
 
 50 
 5 
 
 1 
 
 Q 
 
 No 
 
 50 
 
 In Merced County arrangements were made through Mr. Wheeler 
 to carry out a test of the dried Calimyrna fig's from within and 
 without the clean-up area on a considerable scale. The test was made 
 by gathering from the drying trays in about seventy different orchards 
 composite samples of 200 figs each at three different times during the 
 harvest season (August 20-October 23), early, middle, and late. Half 
 of each sample (100 figs) was sent to the University and the other half 
 to Mr. B. J. Howard of the Office of Food, Drug, and Insecticide 
 Administration, United States Department of Agriculture, who was 
 temporarily stationed at Fresno. Most of the samples were taken by 
 Mr. T. D. Southward under Mr. Howard's instructions. 
 
 The samples sent to Mr. Howard were graded by him by his official 
 methods for commercial fig testing (Howard, 1929). According to 
 this classification dried figs are graded into the following seven 
 classes: insect-infested, moldy (including smut), endosepsis, sour, 
 filthy (including bird-pecked), worthless, and passable. The exami- 
 nation is made with the naked eye or a low-power magnifier and 
 purports to be simply a commercial grading and not a scientific 
 diagnosis of specific diseases. In doubtful or border-line cases com- 
 mercial quality governs, rather than strict pathological analysis. 
 
 In the cases of the samples sent to the University an attempt was 
 made to identify as accurately as possible the presence of all kinds 
 
Bul. 506] 
 
 Fruit Spoilage Diseases of Figs 
 
 71 
 
 and degrees of infection regardless of commercial standards. It was 
 
 found that such diagnosis cannot be made in dried figs on account of 
 
 the dying out of certain organisms and the appearance or increase of 
 
 others as the fig dries ; consequently, the results given here will be based 
 
 entirely upon the commercial grading made by Mr. Howard. 
 
 Table 13 summarizes the results of Mr. Howard's examination of 
 
 161 samples from seventy different orchards, grouped according to 
 
 the treatment given for the disinfection of the mamme figs which 
 
 were used for caprifying the profichi. Acknowledgment is due to 
 
 Mr. Howard and Mr. Dooley Wheeler for these figures. Four classes 
 
 are distinguished comprising (1) orchards in the clean-up area where 
 
 all the growers applied the methods to the best of their ability; 
 
 v zJ ) individual clean-up orchards where neighboring orchards were not 
 
 treated; (3) partly treated orchards where some of the caprifigs were 
 
 disinfected and some not; (4) orchards in which no clean-up was 
 
 attempted. 
 
 TABLE 13 
 Average of Kestjlts of Fig Tests, Merced County, 1929, by B. J. Howard 
 
 District 
 
 Number 
 
 of 
 samples 
 
 Per cent 
 
 insect 
 infested 
 
 Per cent 
 
 mold 
 and smut 
 
 Per cent 
 endo- 
 
 sepsis 
 
 Per cent 
 sour 
 
 Per cent 
 filthy 
 
 Per cent 
 worthless 
 
 Per cent 
 total 
 bad 
 
 Per cent 
 
 total 
 passable 
 
 1 
 
 79 
 
 6.8 
 
 10 9 
 
 6.45 
 
 3 33 
 
 3 5 
 
 1.0 
 
 32 08 
 
 67 92 
 
 2 
 
 27 
 
 9 8 
 
 15 6 
 
 16 5 
 
 4 3 
 
 3 3 
 
 1.0 
 
 50 5 
 
 49 5 
 
 3 
 
 31 
 
 7.7 
 
 9 9 
 
 14 9 
 
 4 9 
 
 4.8 
 
 2 
 
 42 47 
 
 57 53 
 
 4 
 
 24 
 
 11.5 
 
 10 1 
 
 19.7 
 
 3 7 
 
 4.8 
 
 0.9 
 
 50.7 
 
 49 3 
 
 It will be observed that the figs from district 1, where complete 
 clean-up was attempted, averaged only about one-third as much endo- 
 sepsis as those of district 4, where no attempt at clean-up was made. 
 The other districts showed only a slight improvement from partial or 
 individual clean-up efforts. It will further be noted that endosepsis 
 clean-up brought about no significant reduction in other diseases. 
 
 CONTROL OF ENDOSEPSIS: GENERAL DISCUSSION 
 
 Location of Caprifig Trees. — From every point of view, it is 
 evident that the present practice of interplanting caprifig trees in the 
 fig orchard is extremely undesirable in relation to the prevention of 
 endosepsis. Failure or partial success in any of the steps about to be 
 discussed in the process of handling the caprifigs leaves a source of 
 continuous contamination in the midst of the edible figs. With the 
 noncaprified varieties (Mission, Adriatic, Kadota), caprifig trees close 
 by are an unqualified nuisance and should not be tolerated if they can 
 
72 
 
 University of California — Experiment Station 
 
 possibly be dispensed with. In Calimyrnas it is often noticeable that 
 there is more endosepsis (also more splitting) in Calimyrna trees close 
 to caprifig trees than otherwise. This is due mainly to two reasons: 
 First, the figs on such trees are overcaprified, and if there is a small 
 percentage of endosepsis among the profichi the total amount of infec- 
 tion will be that much greater. Second, the percentage of infection 
 
 Fig. 40. — Old, spent, moldy mamme fig and fresh profichi. From mamme 
 figs like this, blastophagas emerge over a long period and carry endosepsis 
 infection into the profichi and thence to the edible figs. 
 
 in the caprifigs keeps increasing in the old, spent mamme (if not 
 removed), the late profichi, and in the mammoni (fig. 40). Blasto- 
 phagas keep on coming out of these and going into the succeeding 
 crops, and also entering the edible figs all summer, even up to the 
 time when they are nearly ripe. Thus there is a continuous danger 
 of infection all through the season, long after caprification has been 
 
Buk 506] 
 
 Fruit Spoilage Diseases of Figs 
 
 73 
 
 finished. Large numbers of blastophagas have actually been found 
 entering' Calimyrna figs that were beginning to soften as late as 
 September 1, and carrying in endosepsis spores at a time when the 
 figs were very easily infected. 
 
 Another objection to caprifig trees in the Calimyrna orchard arises 
 in years when the caprifigs are seriously injured by frost. At such 
 times the trees may be covered with mamme figs like those shown in 
 figure 41. These figs are not worth gathering for dipping" .and capri- 
 fying the profichi, but if left on the trees they become overgrown with 
 
 -**- 
 
 Fig. 41. — Frozen, moldy mamme figs, which are worthless for dipping and 
 caprifying, but which must all be removed and destroyed to prevent the escape 
 of many fungus-contaminated blastophagas — an argument against planting 
 caprifig trees in the Calimyrna orchard. 
 
 endosepsis fungus and other molds and from them emerge many 
 heavily contaminated blast ophaga. It is a difficult and expensive task 
 to remove all these worthless and dangerous mamme figs from the 
 trees, but when they are in the fig orchard there is no alternative if 
 clean fruit is to be produced. 
 
 If the practice of growing caprifig trees in Calimyrna orchards is 
 to be abandoned, the question naturally arises, where should they be 
 planted ? The small grower having not over 10 or 20 acres of land in 
 his entire ranch would do well to have no caprifig trees at all but 
 depend upon buying his profichi from a clean source. On a large place 
 the caprifig trees should be as far as possible from the fig orchard. 
 
74 
 
 University of California — Experiment Station 
 
 The possibility of planting comparatively large, completely isolated 
 blocks of caprifig trees in frost-free places where they can be grown, 
 pruned, shaped, and handled in the best possible manner for the pro- 
 duction of clean profichi by the methods of annual stripping and 
 dipping of the mamme crop suggests itself more and more strongly 
 if this clean-up method continues. The caprifig orchard planted 
 several years ago by the California Peach and Fig Growers, Inc., 
 near East Orosi is fairly well adapted to such a purpose (fig. 42). 
 This is a solid planting of about 50 acres of caprifigs of different 
 varieties in an almost frostless location. Groups of fig growers in 
 various localities might well consider establishing such plantings at 
 convenient, isolated points where the most careful methods could be 
 
 Fig. 42. — Caprifig orchard of the California Peach and Fig Growers, Inc., 
 located in the foothills of Tulare County, California, near East Orosi. 
 
 applied for producing clean profichi figs. In such a case, it is possible 
 that arrangements could be made for testing and certifying the 
 caprifigs under state authority. 
 
 It has been suggested that for the production of clean caprifigs 
 two well-separated plantings of trees be maintained, one (A) 
 for mamme figs, and the other (B) for profichi. In orchard B the 
 mamme figs would be entirely removed and destroyed early in the 
 winter. In orchard A the mamme figs would be allowed to reach full 
 maturity on the tree and could then be harvested, treated, and used 
 for caprifying the profichi in B. 
 
 If such plantings were made, the caprifig trees now growing in the 
 Calimyrna orchards could be top-worked to the edible variety. 
 
Bul. 506] Fruit Spoilage Diseases of Figs 75 
 
 Varieties of Caprifigs. — There are in California caprifigs of a 
 number of named varieties, each having- certain desirable or undesir- 
 able qualities, such as those relating to the size of the different crops, 
 size of the individual figs and the number of insects produced, time 
 of maturity, and other features. Adaptability to harvesting and 
 dipping of the mamme crop now becomes a factor of importance in 
 this connection. The subject is too new to permit any critical judg- 
 ment of the different varieties from this point of view. It may be said, 
 however, that a variety with large, open mamme figs, like the upper 
 ones in figure 43, is better adapted to splitting and dipping than one 
 with small, solid figs like the lower ones in this figure. 
 
 Fig. 43. — Mamme figs of two varieties, showing the internal structure and 
 its relation to injection or dipping in a fungicide. The larger variety has a 
 more open center and is better adapted to treatment than the small, solid figs 
 below. 
 
 Complete Removal of Mamme Figs Necessary. — One of the greatest 
 obstacles to the success of this method is the difficulty of getting off 
 all the mamme figs from the trees. The reasons for this are well 
 understood by anyone who has ever tried it. The trees are often large 
 while the figs are small and inconspicuous. With ordinary hired help 
 the task is absolutely hopeless, but even the owner himself seldom does 
 a complete job except by going over the trees again and again in 
 different lights and from different angles. Growers sometimes think 
 that if they gather and treat most of the caprifigs, a few left on the 
 trees will not do any harm ; but they can make no greater mistake than 
 this. A mamme fig which is removed from the tree and split and 
 dipped is put back into the tree for only a few days and probably 
 
76 University of California — Experiment Station 
 
 produces but a comparatively small percentage of blastophaga. A fig 
 which stays in the tree, on the other hand, keeps discharging insects 
 over a much longer period, has no loss of insects from artificial 
 storage, splitting, dipping, drying, etc., and may during the caprifying 
 season produce enough contaminated insects to infect a large number 
 of profichi, each of which in turn may multiply the dissemination of 
 endosepsis by many fold in the Calimyrnas (see fig. 40). 
 
 About the most difficult situation in this respect is presented by 
 large, unpruned, brushy caprifig trees, from which it is physically 
 impossible to get all the mamme figs (fig. 7). In the case of a great 
 many such trees enough figs are left after the tree is supposed to have 
 been stripped to set a large number of profichi, most of which are 
 infected. For this reason pruning caprifig trees to a low spreading 
 form and cutting the tops of large ones is advisable. 
 
 To insure the control of endosepsis a systematic method of cleaning 
 all mamme figs from the trees must be practiced. A good method is 
 to go over the trees limb by limb, clearing all the figs from one branch 
 before going to another. In Merced County, where removal of mamme 
 figs has become a regular practice, the following method has been 
 developed : A canvas sheet is first spread on the ground, covering the 
 space beneath the tree. A gang of men then proceed to remove all 
 the mamme figs in sight, pulling them off by hand and also using wire 
 hooks mounted on light poles. Following the main crew an experi- 
 enced inspector then goes over the tree with the utmost care, and 
 usually finds a surprisingly large number of figs. After that, in 
 organized districts, other inspectors follow (and still detect an occa- 
 sional mamme fig) until no more can be found. Care must be taken 
 to pick up all figs from the ground after the canvas is lifted. 
 
 Time of Removing Mamme Figs from Trees. — Tests have been made 
 of removing the mamme figs at different times from December to 
 April. It has been shown in the past that it is possible to gather and 
 store the figs through the winter, in order to avoid frost damage. In 
 relation to endosepsis control there are two main considerations about 
 this, and these conflict with each other. First, it is desirable to leave 
 the figs on the trees just as late as possible in order to develop and 
 preserve the insects normally up to the time of caprifying the profichi. 
 Second, the mamme figs must all be removed before any insects begin 
 to come out and enter the profichi. Theoretically it would be best to 
 leave the mamme on until just as the first blastophaga begin to emerge. 
 Practically it cannot be timed as closely as this because it takes con- 
 siderable time to go over a number of caprifig trees and to treat the 
 
Bul. 506] Fruit Spoilage Diseases of Figs 77 
 
 figs. All mammes should have been harvested in an average season 
 by about March 20 in Merced and Stanislaus counties and by March 15 
 in Fresno and Tulare counties. As a general rule, where there is any 
 considerable number of trees to go over, the work should be started 
 about March 1. Unless harvesting of mamme figs is entirely finished 
 before any insects come out and enter the profichi, the object of the 
 operation will be defeated. 
 
 Storing and Handling Mamme Figs. — After the mamme figs are 
 picked from the tree they must be stored in some way to keep them in 
 normal condition until it is time to use them. First, they should be 
 carefully sorted and all frozen, bruised, moldy, or defective figs 
 removed and destroyed. The good ones may then be kept for some 
 time in boxes in a well-ventilated room or cellar. The storage tem- 
 perature should be as nearly as possibly the same as that outdoors. 
 For longer storage it is better to bury the mamme figs in dry sawdust. 
 They should be stored and handled as far away as possible from the 
 caprifig trees and in a tight room to prevent the escape of the 
 blastophaga. 
 
 Disposal of Surplus Mamme Figs. — All surplus, defective, or 
 worthless mamme figs should be destroyed by burning or by some 
 other certain method and not left where there is any chance of the 
 blastophaga emerging and reaching the profichi. Caprifigs remain 
 viable for a long time when lying on the ground in the winter time 
 and no chance of infection from this source should be taken when 
 attempting to clean up endosepsis. 
 
 - Time for Dipping and Caprifying. — This should be governed by 
 the condition of the profichi and must be determined by personal 
 judgment rather than by any fixed standard. The size of the figs is 
 not a safe criterion, but a certain odor or fragrance is characteristic 
 of the receptive condition of the profichi. The condition of the mamme 
 figs and that of the insects is also important. Under natural con- 
 ditions the blastophaga do not all emerge from the mamme figs and 
 enter the profichi at the same time, but the process is an intermittent 
 one, scattered over many days or even weeks. When the first profichi 
 seem to be receptive, therefore, the mamme figs should be sorted over 
 and some of the most mature ones selected for use. This is determined 
 by the softness of the fig and possibly the emergence of the first male 
 blastophagas from the galls. 
 
 Incubation of Mamme Figs. — Various attempts have been made to 
 stimulate the emergence of the blastophaga at a given time by keeping 
 the caprifigs at a fairly high temperature, say 75° to 80° F for 24 
 
78 University of California — Experiment Station 
 
 hours or more just before splitting- and dipping them. It has fre- 
 quently been demonstrated that the desired result can be attained by 
 this method ; as to whether it is necessary there is some difference of 
 opinion. On the whole it is perhaps true that in the past the insects 
 have been hurried too much and many blastophaga have been wasted 
 by too early emergence. On the other hand, it should be remembered 
 that the dipped mamme figs are left in the trees for only a few days 
 and the insects must emerge promptly if at all. The best method may 
 be, therefore, to wait until a large proportion of the profichi are fully 
 receptive and then warm the mamme figs for 24 hours and use a warm 
 solution for dipping. Several successive applications of mamme figs 
 are better than one application. 
 
 Dipping and Caprifying. — The following directions may be fol- 
 lowed : Make a small cut into the fig, right through the eye, and break 
 the two halves apart. Do not cut all the way through the fig, for by 
 doing so many insects are killed and the sterilization process is inter- 
 fered with. Some prefer to split the figs into quarters, leaving them 
 attached together at the stem end, but the penetration of the solution 
 is not as good with this method, and the interior of the fig retains 
 moisture which favors the growth of the endosepsis fungus and other 
 molds. 
 
 Now submerge the figs in a solution of Semesan, 1 ounce to 4 gallons 
 of water, squeezing them gently to separate the galls and allow the 
 fungicide to reach every part of the cavity. Let the figs remain sub- 
 merged for about 15 minutes and while they are submerged squeeze 
 them gently from time to time to eliminate any air pockets that may 
 have formed among the galls. The dipping process may be improved 
 by using two containers of the solution, first submerging the cut 
 figs in one and then, as they are squeezed, transferring to the other. 
 In this way every fig is sure to be squeezed. Five thousand figs may be 
 sterilized in 4 gallons of the fungicide, after which it should be replaced 
 by a fresh solution. If the solution is made with warm water and the 
 temperature kept up to 75° or 80° F the activities of the insects will 
 be considerably hastened. A vacuum dipping apparatus would seem 
 desirable in order to draw out the air bubbles in the figs and obtain 
 complete penetration of the solution among the galls. In such a 
 method, however, caution must be used not to drown or asphyxiate 
 the blastophaga. Figure 44 shows an experimental outfit which has 
 been used for this purpose, consisting of an electrically-driven air 
 pump and a vacuum chamber. The solution is placed in the latter, 
 the cut figs are added, then the lid is clamped on and the exhaust is 
 
Bul. 506] 
 
 Fruit Spoilage Diseases of Figs 
 
 79 
 
 run as long- as desired. The tendency is for too much moisture to be 
 absorbed by the tissue of the fig, leaving it in a saturated, soggy 
 condition. 
 
 After the figs have been treated, drain off excess solution and dry 
 them as quickly and thoroughly as possible. This is important because 
 the endosepsis fungus develops in moist figs much faster than in dry 
 ones. 
 
 Fig. 44. — Vacuum dipping apparatus for treating mamme figs, consisting 
 of exhaust pump, motor, and dipping chamber. 
 
 The cut mamme figs are then placed in the caprifig trees for capri- 
 fying the profichi. It has been recommended that they be put into 
 tin cans or paper sacks to avoid excessive evaporation, furnish pro- 
 tection for the blastophaga, and distribute the mamme figs over the 
 tree in several containers rather than all in one place. Figure 45 
 shows a popular method, putting two open-topped paper sacks con- 
 taining cut and dipped mamme figs into a fruit basket and hanging 
 one or more of these in the tree. In other cases the sacks were hung 
 directly in the tree without the baskets. 
 
 The figs must be taken out of the trees and either destroyed or 
 retreated within four days, in order to keep the endosepsis fungus 
 and other molds from developing on the surface of the cut pieces. 
 The drier the figs are the longer they can stay in the trees without 
 redipping. It is often the case that at the end of four or five days the 
 
80 
 
 University of California — Experiment Station 
 
 blastophaga are just emerging abundantly and caprification is seri- 
 ously interfered with, and many insects lost by dipping the mamme 
 figs again at such a time. Nevertheless, the endosepsis fungus is 
 equally active and much infection of the profichi may result if the 
 dipping is not repeated. More blastophaga sometimes emerge after 
 the second dipping than the first, especially if hot water is used. After 
 a second four-day period the mamme figs should again be removed and 
 
 Fig. 45. — Method of caprifying caprifig tree for setting profichi crop by 
 hanging fruit basket containing two paper sacks of treated mamme figs. Box 
 on ground illustrates another method. 
 
 destroyed, unless there is a great shortage and a third dipping seems 
 worth while. No mamme figs should ever remain in the trees more 
 than four or five days, for the fungus will gradually develop on them 
 and a few straggling, late-emerging blastophagas may pick up the 
 spores and contaminate a large number of profichi. It is very 
 desirable that a method be developed of more permanently sterilizing 
 the mamme figs so that they may stay in the trees longer without 
 redipping. The possibility of using a dry, powdered fungicide in dust 
 form rather than a liquid is being investigated. 
 
Bul. 506] 
 
 Fruit Spoilage Diseases of Figs 
 
 81 
 
 Figures 45 and 46 illustrate a method which has recently come 
 into vogue of putting large quantities of dipped mamme figs into flats 
 or lug boxes and placing these on the ground under the caprifig trees. 
 If one has plenty of mamme figs and the insects are active, a box needs 
 to stay only a short time under one tree to caprify all the receptive 
 profichi and they may be frequently moved from tree to tree or 
 redipped. 
 
 Fig. 46. — Caprifying profichi crop of caprifigs by exposing a large number 
 of treated mamme figs in a box on the ground. This makes it easier to gather 
 up the figs for redipping. See page 81. 
 
 Use of Untreated Caprifigs. — Many growers, after malting a great 
 effort to clean up their caprifigs, have made the fatal mistake of bring- 
 ing in a lot of untreated mamme figs at the last minute, for fear of 
 not having enough. In this connection it should again be emphasized 
 that an untreated caprifig may produce many more blastophaga than 
 one which has been picked early, split, and dipped, and even a very 
 few untreated mamme figs may contaminate almost every profichi on 
 the tree. 
 
 Caprification of Calimyrna Crop. — This is done in the usual manner, 
 with profichi which were set by blastophagas from the treated mamme 
 
82 
 
 University of California — Experiment Station 
 
 fig's. The smallest possible number of profichi should be used, scattered 
 over the tree rather than all in one container. Light caprification, 
 even without any treatment, produces less endosepsis than an over- 
 abundance of insects. A light, clean crop is better than a heavy setting 
 of rotten figs. Here again, as with the mamme figs, if an effort at 
 cleaning up is being made, no profichi from untreated trees should be 
 used to supplement the others, even though there is some shortage. 
 
 Fig. 47. — Box of split and dipped mamme figs used as in figure 46. Note 
 blastophagas on surface of the figs. Quartering the figs in this manner is not 
 as effective as splitting them into separate pieces; the solution does not penetrate 
 as well and the inside of the fig holds the moisture too long. 
 
 How Often Must Clean-up for Endosepsis be Practiced? — The 
 evidence at present indicates that removing and treating the mamme 
 figs every year is the only way to ensure control of endosepsis. It 
 was thought at first that by testing the mamme figs to determine the 
 percentage of infection, those which showed a low count, say less than 
 10 per cent, might be used without treatment. Apparently, however, 
 the fungus builds up so rapidly in the profichi that this is not safe. 
 
Bul. 506] Fruit Spoilage Diseases of Figs 83 
 
 Individual Versus District Clean-up of Endosepsis. — The question 
 is often asked whether an individual grower can produce clean figs 
 even though his neighbors do nothing. This question is well answered 
 in the data given in table 13. A comparison between the amount of 
 endosepsis which developed in orchards in districts 1 and 2, where 
 the clean-up of individual orchards was the same, shows the poor 
 results obtained by treating orchards in which nothing was done in 
 those surrounding them. It is absolutely necessary that entire districts 
 be handled uniformly in order to obtain good results. It will also be 
 found much more satisfactory if all the growers in the district can 
 be induced to do the work voluntarily than if any of them must 
 be driven to it by force. There must, however, be some central, 
 legalized authority to direct and inspect the work if it is to progress 
 satisfactorily. 
 
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 Cajldis, P. D. 
 
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 1930. Souring of figs by yeasts and the transmission of the disease by 
 insects. Jour. Agr. Ees. 40:1031-1051. 
 Coit, J. E. 
 
 1921. Fig splitting and souring can be reduced. Pacific Eural Press 101:300. 
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 1917. Proceedings of the Fig Institute, 1917:1-111. Published by the Fresno 
 
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