CALIFORNIA AGRICULTURAL EXPERIMENT STATION CIRCULAR 384 APRIL, 1948 CONTROLLING COMMON PESTS OF TOMATO IN NORTHERN CALIFORNIA A. E. Michelbacher, W. W. Middlekauff, N. B. Akesson THE COLLEGE OF AGRICULTURE UNIVERSITY OF CALIFORNIA * BERKELEY IN WARFARE ON TOMATO PESTS, YOU SHOULD— Knw THE ENEMY The damage done by tomato pests ranges from a nuisance to devastation. Each of these common pests has its own way of living and behaving. An acquaintance with the appearance and the habits of each is the first need in a planned control program. The first pages of this circular describe the tomato pests of im- portance to you. Know THE WEAPONS To eliminate tomato pests it is neccessary to know the best weapons as well as to know the enemy. Therefore, information about insecticides— what they will and won't do— and about the equipment for applying them, is briefly given. Plan THE CAMPAIGN This circular is intended to do one thing primarily: to encour- age the tomato grower to carry through a well-integrated con- trol program, in which he considers all the important pests and provides systematic protection to the crop throughout the sum- mer and fall. His goal should be ADEQUATE but not wasteful PROTECTION THE AUTHORS— A. E. Michelbacher is Assistant Professor of Entomology and Assistant Ento- mologist in the Experiment Station. W. W. Middlekauff is Assistant Professor of Entomology and Assistant Ento- mologist in the Experiment Station. N. B. Akesson is Instructor in Agricultural Engineering and Junior Agricul- tural Engineer in the Experiment Station. [21 CONTROLLING THE COMMON PESTS OF TOMATO IN NORTHERN CALIFORNIA A. E. Michelbacher, W. W. Middlekauff, and N. B. Akesson Pests which are associated with vir- tually every tomato planting, once the plants are established in the field, are, first and earliest, the tomato mite, and then through the season numerous kinds of caterpillars. The most prevalent cat- erpillars are known by the common names of yellow-striped armyworm, beet army- worm, alfalfa looper, various night- feeding cutworms, tomato pinworm, potato tuber moth, tobacco hornworm, tomato hornworm, and corn earworm. As is suggested by their names, some of these caterpillars prefer plants other than tomatoes and attack the latter only when their preferred hosts no longer are avail- able. The Mite— The tomato mite feeds and reproduces on a number of cultivated plants, notably tomato, potato, and petunia. It reproduces from eggs and passes through many gen- erations in a season. Continuous repro- duction has been reported from early May until frost. The mite is too small to see with the naked eye but under the microscope is somewhat pear-shaped, and tannish-white in color. It crawls about slowly on the surface of the leaves, stems, and fruit of the tomato plant and sucks out the cell contents. The infestation usually starts near the ground and as it progresses up the plant the lower leaves become dry, giving the plant an unhealthy appear- ance. The color of the stems and leaves frequently becomes greasy bronze or russet. If not controlled, the pest causes se- rious defoliation which is particularly rapid during periods of hot weather. The result is sunburned fruit and crop loss. Tomato mite appears early in tomato fields and usually requires control meas- ures in advance of the other pests. Tae Caterpillars— The caterpillar is the second of four distinct stages of development which butterflies and moths go through: egg, larva (caterpiller),pupa (chrysalis), and adult (moth). Damage is inflicted only during the larval, or caterpillar stage. Moths lay the eggs but do no damage, and they serve as a warning of the cater- pillars to come. The control program must be directed against the caterpillars them- selves. The life histories of all of the cater- pillars are somewhat similar. Eggs, which have been laid on the plant by the adult moths, hatch after three to five days. The small caterpillars eat their way to matur- ity, casting their skins several times as they grow. During this period they do their damage to plant, leaves, or fruit, each in his own way. On completing development as larvae, the caterpillars begin construction of their pupal cells. Most of the pests of tomato will burrow into the soil, build their cells a few inches below the sur- face, and construct tunnels upward to within half-inch of the surface for the subsequent emergence of the adult moth. However, the alfalfa looper spends its pupal life in a light silken cocoon it has spun on a leaf or in the debris under the plant. The pupal stage varies in length for each of the different kinds of caterpillars, m and also varies with the weather. For ex- ample, the corn earworm has a pupal period of two to three weeks during the summer, but the fall broods will remain in this stage over winter. Egg Laying Begins When the pupal stage is over, the adult moths emerge, expand and dry their wings, mate, and after a day or two begin laying their eggs in great numbers. Usu- ally at dusk on warm days the female moths of the corn earworm may be seen flitting here and there, seldom flying higher than the tops of the plants, and laying eggs at random over the vines. A single moth will lay 500 to 3,000 eggs during her lifetime. With the hatching of these eggs another generation begins its life cycle. Some species, such as the tomato hornworm, will have three generations a season, but others, such as the tomato pinworm, will pass through as many as seven or eight generations in a year. Know the Pests by the Damage They Do While the life histories of all of the caterpillars are quite similar, the damage they inflict to tomatoes may differ widely. The visible evidence of this damage serves as the best clue to the kinds of pests pres- ent, and indicates the kind of treatment which should be applied. Corn Earworm The corn earworm is considered the most destructive caterpillar due to its abundance and wide distribution, and to the fact that it normally completes its en- tire larval development in the fruit. This pest prefers corn and beans, and turns to tomato late in the summer when the for- mer crops have passed their maturity and are drying up. If it becomes established in the tomato fields in August there is still sufficient time for two broods to appear before tomato harvest is completed. HMH Corn tarworm may spend its fife in the fruit , . . [4] Where infestation is severe more than 50 per cent of the tomatoes may be destroyed. Entry is usually made at the calyx end or the stem end and some larvae are so small that one must look carefully to de- tect the point of penetration. The cater- piller may emerge from one fruit and enter another. There is a strong tendency for the small corn earworm to enter de- veloping tomatoes % to 2 inches in di- ameter. Therefore the beginning of an infestation can be determined by picking and thoroughly examining fruit in this size range. A control program need not be started until 2 to 3 per cent of the fruit in this stage of development shows signs of infestation. No less than 300 fruits should be picked at random throughout the field in determining the degree of in- festation. Late in the harvest season the small larvae may enter the ripe fruit as well, causing the canner much annoyance because these infested fruits are nearly impossible to detect. Yellow-Striped Armyworm (See picture on front cover.) While occurring in greatest numbers on alfalfa, the yellow-striped armyworm infests many kinds of cultivated and na- tive plants. Although not a serious pest of tomato every year, on occasions it is very destructive. Infestations in tomatoes arise from moths which fly into tomato fields, or from caterpillars which migrate from adjacent alfalfa fields when the latter are cut. This pest feeds both on the foliage and on the fruit of the tomato. It does not enter the fruit, but eats irregular holes in its surface. Its most serious attack on tomato occurs from July through the middle of September. Beet Armyworm One of the most common and wide- spread pests in California, the beet army- worm is to be found in tomato fields every year, and at times in certain fields it has * ■ . . . resulting in damage like this [5] Tiny, webbed burrows make pinworms hard to find m. been found to be the most important caterpillar attacking tomato. The beet armyworm is primarily a foliage feeder, but it will also seriously attack the fruit, eating single or closely grouped circular or irregular holes. In many cases the feeding is of a very super- ficial nature, and little loss would be suf- fered if it were not for rot and decay entering the wounds. This pest is most common and destruc- tive in the warmer interior valleys where it is abundant from late July until early November. In severe cases of infestation it is not uncommon to find an average of 25 to 50 caterpillars to a tomato plant. Alfalfa Looper These caterpillars are easily distin- guished from others by the fact that in crawling they arch their backs, for which characteristic they are called "loopers." The alfalfa looper is a foliage feeder and only rarely will it feed on a fruit. Although it may be encountered in fair abundance, the damage is usually insuffi- cient to require" special control measures. Potato Tuber Moth Tomatoes are subject to infestation by the caterpillar of the potato tuber moth over a large portion of California. They appear to be most prevalent in the coastal regions and the San Joaquin Valley. Serious infestations are almost always associated with potato culture. Where tomatoes follow potatoes and where there are volunteer potato plants there is al- ways the danger of a serious infestation developing. Usually less than 5 per cent of the tomatoes in a field show infesta- tion, however, damage to as high as 57 per cent of the fruit has been found. These larvae prefer to enter the fruit at the calyx end, making a dry burrow through the core and the fleshy portions which radiate from it. They may enter at any point, however. They usually spin a web over the entrance to their burrows, and the fruit must be carefully observed to detect damage. Tomato Pinworm This caterpillar is a leaf -miner and leaf- folder, but during the last half of its larval [6] existence it also frequently bores into the fruit. Where abundant, the tomato pinworm may cause serious damage to the foliage, and nearly 100 per cent of the fruit may be infested. The larvae will enter the fruit at any point. They make dry burrows, are small, and usually do not penetrate very far into the fruit. After an infested fruit is picked, the caterpillar quickly spins a web over the entrance to its burrow, making its pres- ence hard to detect. Because the pinworm breeds a number of generations in a season, it becomes more serious as the season advances. Greatest damage is likely to occur where tomatoes are produced from early in the growing season to late in the fall. Night-Feeding Cutworms There are several species of cutworms which attack tomato only at night. Under some conditions they are likely to be quite destructive. All feeding is done at night; the caterpillars hide in the soil or sur- face debris during the day. These pests injure tomatoes by eating irregular holes in the surface, and toma- toes that rest on the ground are in general the most seriously injured. Early in the season this group of cut- worms may cause serious damage by cutting off recently transplanted tomato plants. Hornworms The tomato hornworm and tobacco hornworm are similar at all stages of de- velopment, and their damage to tomato also is similar. They feed on the blossoms and fruit but are most important because they will strip the leaves from tomato vines and if severe infestations go un- checked, they may defoliate an entire field. Hornworms are particularly serious in the warmer interior valleys. Defoliation like this is typical hornworm injury [7] MEET THE ENEMY. . . MATURE CATERPILLARS OF ACTUAL SIZE TOMATO PINWORM ^rrarc.'-fl. POTATO TUBER MOTH LARVA ALFALFA LOOPER BEET ARMYWORM YELLOW-STRIPED ARMYWORM CORN EARWORM TOMATO HORNWORM TOBACCO HORNWORM i/ 4 " w l'/a" [8] Acquaintance with these major caterpillar pests is the first line of defense in any control program HOW THE CATERPILLARS LOOK WHERE YOU'LL FIND THEM When newly hatched, the tiny larvae are light pink; when fully grown to Va inch they appear grayish purple. In a folded leaf, or in dry burrows in a fruit. When fully grown these caterpillars are white, yellow, pinkish or greenish with head and prothoracic shield dark brown. In dry burrows in the fleshy part of the fruit. These caterpillars are pale green and longitudinally striped with fine, whitish lines. In crawling they arch their backs and hence are called loopers. On the leaves, as they are primarily foliage feeders. They appear in several color phases which range from pale green to nearly black. They are darker above than below, and down each side is a lighter stripe. Fine lines run along the dorsal side. On the foliage, usually toward the inside of the vine, or on the outside of the fruit. This is a striking looking caterpillar, almost black with two prominent and many fine, bright yellow stripes on the side. On the foliage, or on the outside of the fruit. Every housewife has a firsthand acquaintance with these. They vary from green to almost black, marked with stripes of various colors. They are sparsely cov- ered with rather long hairs arising from tubercles. Inside the fruit in all stages of growth. This creature is green and has seven diagonal white stripes on its side, and a red horn at the rear. On the vine, which they may completely defoli- ate. Similar in appearance to the tomato hornworm, but can be distinguished by the eight "V-shaped" mark- ings formed by longitudinal and diagonal stripes down the sides. In the larger specimens the horn is black instead of red. On the vine, which they may completely defoli- ate. Pictured are the fully-developed caterpillars. The TOMATO MITE — another major enemy of tomato — is not pictured because of its microscopic size. [9] THE CONTROL PROGRAM FOR NORTHERN CALIFORNIA The following schedule for applications of insecticides is partic- ularly adapted to northern California conditions, where canning tomatoes are predominant. In the central and southern San Joaquin Valley the program should be put into operation as early as late- May or June, and continued as long as there is evidence of pest damage. July U15 Because the tomato mite is the first pest to make an appearance, the first treatment should be directed against it by dusting with sulfur. This treat- ment probably will be needed by July 1 to 15. During this period horn- worms, yellow-striped armyworms, and beet armyworms may be making their appearance. Where this occurs, an effective insecticide should be used in conjunction with sulfur to control them. August U15 During early August the important insects to control are the beet army- worm, yellow-striped armyworm, and hornworms. A suitable insecticide should be applied to check their damage. At the same time the application will control the few corn earworms which may be appearing. The insecti- cide should also contain sulfur to continue the control of the tomato mite. September U15 Early in September a third treatment is needed and is primarily directed against corn earworms, but should also be effective against armyworms and hornworms which are certain to be present. If damage by the tomato mite is not apparent, sulfur may be excluded. Sampling Any application of insecticides should be based upon a knowledge of the insect pests present. An examination of from 200 to 600 fruits, depending on the size of the field, should reveal the kinds of insects present and the degree of infesta- tion. These samples should be taken at random from all parts of the field, as incidence of pests may vary widely from one spot to another. [10] Hature and Cultural Methods Aid Pest Control Control of caterpillars attacking to- mato would be a much more difficult problem if it were not for natural factors which tend to hold destructive pests in check. Important among these are preda- tors, parasites, and diseases. Weather, also, may have an adverse effect. In spite of these natural limiting fac- tors, some of the many pests are likely to reach a destructive level. The tomato grower can meet the problem in two ways. He can adopt cultural practices which are unfavorable to the pest, and secondly, he can employ specific pest-control measures involving the application of effective in- secticides. Natural Enemies Caterpillars infesting tomato are sub- ject to the attack of a number of parasites and predators. The full value of these enemies has never been determined, but it is known that certain of them are re- sponsible in a large measure for some species of caterpillars not reaching a de- structive level every year. One parasite which attacks the corn earworm and the yellow-striped armyworm has been ob- served, and is recognized as an important controlling factor of these pests. The action of the many parasites upon their host, and the influence they exert in regulating populations is a subject that is in need of thorough investigation. It is important that insecticidal control pro- grams be developed that will supplement the work of the natural parasites. Cultural Methods The destruction of crop refuse is a sani- tary measure that should be practiced. It is particularly important in regions where the tomato pinworm or the larvae of the potato tuber moth is a problem. Where the pinworm is a pest, growing of an early and late season crop should be avoided if this is at all possible. If two crops are grown, refuse from the first should be destroyed by burning or plowing under just as soon as harvest is completed. The practice of following potatoes with tomatoes should be avoided. Most exten- sive damage by the larvae of the potato tuber moth has usually been found in those fields where volunteer potato plants have been growing. Infestations by the corn earworm on tomatoes are likely to be most severe in areas where sweet corn and beans are grown. The farmer must encourage the destruction of crop refuse as soon as these preferred hosts are harvested. Insecticidal Control Program The problem of controlling tomato pests should be approached from the wider viewpoint of the seasonal program. The well-integrated control program will be built around all the important pests and will provide protection throughout the bearing season. In this circular only those pests which attack the crop from early summer to the end of. harvest are considered. Recommendations herein concerning insecti- cides and their application are made at the conclusion of two years of extensive experimen- tation by the authors on small replicated plots and on commercial plantings. Earlier tomato investigations, begun in 1935, had already de- termined the life histories and habits of the insects, as well as the best control measures based upon the insecticides available before the advent of many new organic compounds. Complete details of the recent investigations are being published concurrently as Bulletin 707 of the Agricultural Experiment Station. The present Circular omits most of the detailed methods and findings of the investigations, and presents only the conclusions which are be- lieved to be of interest and value to a larger number of readers. [ii] The Insecticides— What They Wilt and Won't Do In selecting insecticides for use as either dust or concentrated spray, the farmer must know the limitations of each of the available compounds, as well as the performance he may expect of each. The following recommendations are made as the result of experimentation dur- ing 1946 and 1947 by the authors. Hand and machine equipment, ground rigs and airplanes, were repeatedly used on small and large plots in the research. The tests employed calcium arsenate as a dust and as a spray, DDT as dust and as spray, DDD as dust and as spray, Toxaphene as a dust, and cryolite as a dust. Sulfur was added to these as needed for the control of the tomato mite. Calcium Arsenate Calcium arsenate has long been one of the most important insecticides used to control caterpillars attacking tomatoes. It has been primarily used as a dust and has given satisfactory control of most caterpillars. In recent years, however, complaints have arisen that drift from this dust has caused arsenical burn of adjacent susceptible crops, and contami- nation of forage crops and bee pastures. The drift of calcium arsenate can be greatly reduced if this insecticide is ap- plied as a concentrated spray instead of a dust. However, the investigation showed somewhat better control of the caterpil- lars with the use of the dust. At the recommended rate of 15 to 25 pounds to the acre, calcium arsenate gives satisfactory control of the corn earworm, armyworms, and hornworms. Against the tomato pinworm and the caterpillar of the potato tuber moth, however, only indiffer- ent control can be expected. DDT and DDD Experiments with DDT (dichloro di- phenyl trichloroethane) and DDD (dich- loro diphenyl dichloroethane) showed that either of these insecticides, used either as dust or spray, is superior to cal- cium arsenate in the control of all pests except the tomato hornworm. In the control of tomato hornworm, cal- cium arsenate is about equalled in effec- tiveness by DDT as a concentrated spray, or by DDD as a dust or spray. Where DDT or DDD is used, not more than 1% pounds of actual material should be applied per acre per application. This is equivalent on an acre basis to 30 pounds of a 5 per cent dust, or 3 pounds of a 50 per cent wettable powder if ap- plied as a spray. For the control of the tomato mite, dusting sulfur can be used in combination with the dusts. Wettable sulfur (15 pounds per acre) can be used in conjunction with the sprays, or the tomato mite control program can be con- ducted as a separate dust operation. Toxaphene Toxaphene is a chlorinated camphene with the technical grade containing 67 to 69 per cent chlorine. Experiments with this compound show that a 10 per cent Toxaphene dust ap- plied at 30 pounds per acre will give about the same results as calcium arsenate against the caterpillar pests. Where the dust contains 25 per cent sulfur, tomato mite control may be obtained in the same application. Cryolite Cryolite as a dust has shown results equal to those of calcium arsenate against all caterpillars except the hornworms. It apparently is rather ineffective against these pests. The cryolite used in the experimental plots was a 50 per cent natural cryolite dust which contained 45 per cent of so- dium fluoaluminate, to which was added 25 per cent dusting sulfur. [12] To Dust or to Spray — The Grower Must Decide The relative merits of the spray method and the dust method of applying insecti- cides must be considered by every farmer who plans a general control program. Application of Sprays During the past two years rapid ad- vancement has been made in the methods of application of concentrated sprays. Observations show that better coverage with sprays is obtained with ground rigs than by airplane. Neither of the methods results in thorough coverage throughout the vine; most of the spray remains con- centrated on the outside of the plants. Airplane application has been greatly improved in recent years but further per- fection is needed. Simplification of equip- ment and better nozzle valves are desired. Clogging difficulties could be reduced by inserting strainers in the boom line. Air- planes equipped with spray booms are capable of uniform distribution of the spray, but the droplet size still appears to be somewhat large. In airplane spray work, constant care and judgment are needed at all times to eliminate mechani- cal defects. Although airplane applications of in- secticides as wettable sprays rather than as dust reduces the drift hazard, it should be remembered that a fine spray also is subject to some drift. This is espe- cially true if applied from too great an altitude or in unfavorable weather. Use of ground machines in the applica- tion of sprays has resulted in satisfactory control. Three types of ground rigs have been used: a compressed air atomizing type; a vapor spray type called vapor or mist sprayer; and a converted high- pressure orchard sprayer. The first two were used in investigations made by the authors; the third is in use by several growers and a commercial operator. The compressed-air atomizing type was found to give good coverage and satis- factory droplet size. However, this ma- chine cannot be recommended because of the mechanical complications involved in the use of the liquid and compressed-air double system, and also because of insta- bility in the mixing and atomizing device. The vapor-spray type of equipment gave good results but had the disadvan- tage of covering only two rows at a time. It is possible that the capacity of the machine can be increased. Where this machine is used the drift hazard is practi- cally eliminated, and the spraying oper- ation is not limited to early morning as is the case with dusting. Satisfactory performance is reported for the converted high-pressure orchard sprayer. This machine is fitted with a boom that covers five rows, with three nozzles per row. It carries a 300-gallon tank, furnished with mechanical agita- tion. In order to secure good coverage with this machine, it is necessary to apply at least 40 gallons of liquid per acre be- cause the machine could not be satisfac- torily adapted for the application of concentrated sprays. The Dusting Method The main problem involved in the dust- ing method is that of drift. Experiments have been made with a tomato duster equipped with a hood and drapes to deter- mine if such a hood would restrict drift. Even under favorable weather conditions the hood proved to be ineffective. The addition of 2 to 4 per cent highly refined oil to calcium arsenate dusts has been tried, but little or no control of drift was observed. The oil kept the drift from boiling high in the air, but did not settle it, and the dust did drift from the field being treated. It appears, therefore, that where dust- ing is done, some drift must be expected. All the operator can do is to apply the dust carefully and in favorable weather. [13] What injury May be Caused by Residues? Injury to Bees and Livestock If carefully applied, DDT and DDD dusts will probably not cause injury to bees. The least damage by dust would occur when these dusts are applied in the early morning when flowers are still closed and bees are not in the fields. It was reported in 1947 by McGregor and Vorhies, after conducting extensive in- vestigations of the effect of DDT in con- nection with beekeeping that "No damage to colonies was detected when nearby cotton was dusted nine times by airplane with 10 per cent DDT in pyrophyllite at the rate of 15 pounds per acre." As far as livestock is concerned, every effort should be made to avoid contami- nating hay or pasturage. This is particu- larly true where dairy cattle are involved because if they feed on DDT-contamin- ated food, some of the DDT is secreted in the milk. . Experiments have shown that DDD is much less toxic to warm-blooded animals than is DDT, and for this reason it might be safer to use the former under condi- tions where there is some danger of con- taminating hay or pasture crops. Insecticidal Residues on Tomatoes The question of poisonous residues always arises in connection with the ap- plication of insecticides. The final authority concerning residues is the Federal Food and Drug Administra- tion. Since no tolerance has been an- nounced for the presence of DDT and related compounds in canned foods, it is imperative that residual amounts of these compounds be effectively removed before the products are canned. For this reason, residue studies were undertaken to determine the effectiveness of removal of DDT and DDD from to- matoes by washing methods similar to those used in commercial canneries. The testing was done by the National Canners' Association Laboratories, and the results were reported to the authors to supple- ment their control investigations. The results of these studies are briefly stated as follows: DDD and DDT on unwashed tomatoes picked the same day the insecticide was applied showed from 0.2 to 1.7 parts per million; the same fruit after washing showed from 0.1 to 0.7 parts per million. Juice prepared from the washed tomatoes contained 0.1 part or less per million of DDT or DDD; while the residue of the pulp after juice was removed contained from 2.7 to 4.3 parts per million of DDT or DDD. Residue of calcium arsenate spray on tomatoes was tested. Unwashed tomatoes picked the same day the last spray was applied showed about 4 parts per mil- lion ; after washing they showed 0.2 to 0.6 parts per million. Arsenic in the juice varied from 0.1 to 0.4 parts per million, and in the residue left after juicing, varied from 0.3 to 0.6 parts per million. Will DDT in the Soil Injure Tomatoes ? Under certain conditions DDT has been known to injure tomatoes. As used in the investigations by the authors, no injury could be traceable to either DDT or DDD. Experiments conducted by other work- ers have shown that 20 to 25 pounds of DDT per acre applied to the soil caused injury to tomatoes planted on the treated land. Because the rate of decomposition in the soil is not as yet adequately known, there is some danger that it may accumu- late in the soil to a dangerous level. Al- though there appears to be no immediate danger involved in its use, since in a nor- mal DDT program only 3 to 4.5 pounds per acre is used in a season, it is hard to [14 1 predict what may happen if the insecticide is used over a period of years. At present it is certain that neither DDT nor DDD have withstood the test of time. Therefore, these insecticides should be used with a great deal of caution. Their application should be made only when there is an absolute need for insect con- trol. They should be thoroughly applied, but over-application should be avoided. Conclusions The investigations reported in this cir- cular should convince the tomato grower of the practical necessity of adopting a control program for tomato pests. A generalized program in the northern part of the state in a normal year calls for three applications of insecticides: The first from July 1 to 15, the second from August 1 to 15, and a third from Sep- tember 1 to 15. Such a program will be based on the natural habits of the pests, their time of appearance and the conditions fostering their growth. It will be specifically de- signed to control several pests at a time, thus saving money by eliminating un- necessary applications. Further, a planned control program will consider the advantages of using one of the new organic insecticides rather than calcium arsenate which has come into disfavor because of drift and attend- ant contamination of nearby fields. It will also consider the relative advantages of dusting and spraying— all with the goal of providing adequate but not wasteful protection to the tomato crop throughout the summer and fall. The time element is the most important part of the program. Which of the insecti- cides to use, and whether to dust or to spray, is a matter for each grower to de- cide for himself. In order that the information in our publications may be more intelligible it is sometimes necessary to use trade names of products or equipment rather than complicated descriptive or chemical iden- tifications. In so doing it is unavoidable in some cases that similar products which are on the market under other trade names may not be cited. No endorsement of named products is intended, nor is criticism implied of similar products which are not mentioned. 12m-4,'48(A8195s) 141 [15] AGP AGRICULTURE . . . Contains brief, easy-to-read progress reports of agricultural research, and is published monthly by the University of California College of Agricul- ture, Agricultural Experiment Station. 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