University of California— College of Agriculture, AGRICULTURAL EXPERIMENT STATION. E. W. HILGARD, Director. REPORT ON CONDITION OF VINEYARDS IN PORTIONS OF SANTA CLARA VALLEY. By FREDERIC T. BIOLETTI and E. H. TWIGHT. DECAYED TRUNK (See page 4.) SOUND TRUNK. BULLETIN No. 134. (Berkeley, Sept. 23, 1901.) SACRAMENTO: a. j. Johnston, ::::::: superintendent state printing. 1901. Digitized by the Internet Archive in 2012 with funding from University of California, Davis Libraries http://www.archive.org/details/reportonconditio134biol UNIVERSITY OF CALIFORNIA, AGRICULTURAL EXPERIMENT STATION. COLLEGE OF AGRICULTURE, E. W. Hilgard, Director. Berkeley. California. August 26, 1901. Professor E. W. Hilgard, Director of Agricultural Experiment Station. Dear Sir: In accordance with your directions we have examined the vineyards of Santa Clara with the object of determining the cause of the failure and death of a large number of vines in parts of that county during the last three years. It is not possible at present to give a com- pletely satisfactory explanation for such serious and widespread damage as has occurred, but our observations seem to prove conclusively two propositions: First, that the dying vines exhibit symptoms differing materially from those shown by the vines in Southern California which were destroyed by the Anaheim disease; and, second, that whether or not there be some " unknown influence " at work, as suggested by Mr. Newton B. Pierce, the real, determining factor is the deficiency of rain- fall during the years 1897-1900. Area and General Character. — The dying of vines without perceptible adequate cause during the last three years has by no means been con- fined to the west side of the Santa Clara Valley. Similar cases have been reported and investigated over a wide area extending from the northern part of Sonoma County, to the western and southern parts of the Santa Clara Valley, and including nearly all the older vineyard districts within these limits. The only peculiarity of the cases on the west side of the Santa Clara Valley is their number, extending in many cases to every vine in a vineyard. The distribution of the injured and dead vines is not in any of the cases examined such as to suggest an infectious parasitic cause. In some instances single vines failed and died sporadically where the main bulk of the vineyard was in fair con- dition, and a dead vine was usually surrounded by vines which were apparently healthy. Nature of Injury. — In most of these sporadic cases examined the dying vine was found to have been severely injured in some way, usually by cutting off large branches at the pruning and thus causing large wounds. Vines of this kind when split open were found to be more or less decayed in the middle, and many were quite hollow. In a report made to you last year on the same subject this decay of the interior of the trunk was suggested as the cause of death in some cases. This year, however, though in some vineyards the hollow vines have continued to __ 4 — fail and die, in others they have recovered. This indicates that though the wood decay may have contributed to the effect, it is not the only, nor indeed the chief cause. The accompanying photograph (plate 1) illustrates the injury done by the cutting off of a large branch. Note in the subjoined figure the large wound which could not heal over, and which allowed a large amount of wood to dry out. Note also PLATE 1. Vine Injured by Heavy Pruning Without Protection to Wound. the hole made by a boring insect, which allowed the entrance of moisture and of white ants, and thus favored the growth of wood-rot fungi. The stem of this vine was found, on being split, to be quite hollow nearly down to the surface of the ground. For the general appearance of vines of this kind see the frontispiece, which is taken from a photograph of one of the vines as it appeared in 1900. Note the contrast with the perfectly healthy appearance of the neighboring vine. Nature of Soil. — Nearly, if not quite, all the cases occurred in grav- elly soil, and the more gravelly the soil the more numerous and serious — 5 — the cases. Soil-borings in the most badly affected vineyards showed a layer of many feet of coarse gravel, commencing at two or three feet from the surface. In attempting to irrigate in these places the growers had much difficulty in causing the water to flow to all parts of the vine- yard. A large stream of water would take many hours in passing a few yards, on account of the extremely leachy nature of the soil, which allowed the water to escape downward. Age of Vines. — It is to be noted that none of the dying vines are young. All the vineyards examined which were less than eight years old showed no indications of failing or dying. All cases of young vines PLATE 2. Two Healthy Trousseau Vines in a Vineyard of Dead Mataro Vines. failing which were examined were plainly due to lack of cultivation, phylloxera, sunburn, or other well-known and adequate causes. Another fact worth mentioning in this connection is that old vines which were grafted just before the three dry years, are now nearly or quite healthy. In one vineyard a block of old Mataro grafted with Verdal about 1896 shows strong growth and no signs of failing, while a contiguous block of the same variety and age, but un grafted, is prac- tically dead. Behavior of Different Varieties. — A great deal of difference was every- where noted in the behavior of different varieties of vines. The most seriously affected were Mataro, Zinfandel, Rose of Peru, Mission, Varieties less affected were Grenache, Muscat, Emperor, and Burger. and Verdal. These three varieties, in many cases where they looked very bad last year and even this spring, appear to be recovering. Other varieties show little or no damage. The chief of these noticed were Trousseau, Cabernet-Sauvignon, Pinot (?), Verdot, Robin noir, and Herbemont. This list indicates that the heaviest bearers are the most seriously affected and that all the immune varieties are light bearers. This difference in varieties was so marked that several Trousseau vines growing in a Mataro block were apparently perfectly healthy and vigorous, while the Mataro were all dead. This is shown in the photo- graph (plate 2). The recovery of less susceptible varieties, such as Grenache, was in several cases very remarkable. Two adjacent blocks, one of Grenache and the other of Mataro, showed a remarkable contrast PLATE 3. Adjacent Blocks of Mataro (Dead) and Grenache (Recovering). when examined in August of this year. Both blocks had made very short growth in 1900, but this year all the Mataro were dead, while none, so far as could be seen, of the Grenache had died, and though the block had looked sickly in the spring, when examined in August it showed a fine growth of luxuriant foliage (see plate 3). To recapitulate; the main facts ascertained are: 1. All the dying vines are old. 2. All the serious cases are in gravelly soil. 3. The varieties most injured are all heavy bearers. 4. Vines grafted before the drought are healthy. 5. Vines showing serious mechanical injuries succumb first. 6. Vines which have not become too weak appear now to be recov- ering. Causes. — These facts seem to indicate that we can ascribe the failure of the vines to a general cause acting over the whole district; a cause, however, which was only effective where supplemented by one or more contributory conditions. These conditions are: 1. Excessively gravelly soil. 2. Susceptibility of the variety of vine, due probably to heavy bearing and perhaps to some peculiarity of wood and foliage, or roots. 3. Large wounds made in pruning. 4. Age of the vine. 5. Severe cutting back of the young growth by spring frosts. The general cause seems to be the combined effect of the heavy crops of 1896 and 1897 and the four years of drought which followed. Rainfall and Crops. — The following statistical table, made up from data furnished by the Weather Bureau and by two of the largest vine- growers in the most seriously affected districts, fortifies the above position : Relation of Precipitation and Irrigation to Crop, in Vineyards in Santa Clara Valley. Precipitation at Santa Clara. Crop on Vineyards at West Side. Departure from Normal Rainfall. A (300 acres). B (170 acres). 1896 Inches. 19.51 11.82 8.13 15.56 13.15 Tons. 1,413 1,883 500 a 449 6315 Tons. dSOO d2l5 d 93 c 94 Inches. +3.24 —4.45 —8.14 1897 1898 1899 1900 .- — .71 -3.12 a Irrigated 35 acres. b Irrigated 300 acres. c Irrigated 70 acres in February. From 50 acres of the irrigated land were obtained 49 tons of grapes, and from the remainder of the vineyard only 45 tons. This indicates about 1 ton per acre on the irrigated and about % ton per acre on the unirrigated portion. d Estimated from the wine produced. If the figures given for these two vineyards are typical, which there is every reason to suppose, they may help us to find a sufficient cause for the death of the vines without taking refuge behind the mysterious and highly unsatisfactory Anaheim disease. In 1896 the vines bore a large crop, but were supplied with sufficient water by a rainfall of three inches above the normal. They therefore entered the season of 1897 healthy, but probably not with an excess of reserve food-material laid up in the stems and roots; for the weakening effect which a heavy crop — 8 — often has upon a plant is due to the fact that the nutriment which it absorbs and assimilates during the summer and autumn is nearly all utilized in the production of fruit, and little is stored for use in the fol- lowing spring. The spring growth of a plant is all due to this reserve food, and is the weaker the less of this reserve it has to draw upon. Usually a year of heavy bearing is followed by a year of light bearing, during which the plant is able to recuperate by utilizing the food assimilated during that year for building up its vegetative organs and for replenishing its depleted reserve. During the season following the heavy crop of 1896, however, the weather conditions were evidently such as to force the vines to expend all their resources in the production of the phenomenally large crop of 1897. How exceptionally large this crop was upon the vines which are now dying is not quite indicated by the table above, which includes the crop from all varieties and ages of vines. The crop on the old vines of heavy-bearing varieties which are now dead was doubtless much in excess of the indicated average. At the same time that this severe drain was being made upon them there was a shortage of over four inches in the annual rainfall. It is practi- cally certain, therefore, that these vines were obliged to start the year 1898 with empty storehouses, and the rainfall of that year being just half the normal, the vines not only bore very little, but were unable to obtain nutriment sufficient to satisfy their vegetative needs and to nour- ish their permanent organs — roots, stems, and canes. The next year, 1899, therefore, they commenced to fail and some of them to die. In 1900 still more died, while in 1901, the present year, the largest mortality of all occurred. It is, perhaps, not quite clear why the mortality should be greatest in the later years when the defi- ciency of rain was less than in 1898, the year of the greatest drought. It should be remembered, however, that a lack of water may affect a plant in two ways: If it occurs at a time when the plant is in vigorous growth and full leaf the plant is injured or killed by diminution of the amount of water in its cells and tissues, due to the excess of evaporation from the leaves over the absorption by the root hairs. In this case the plant dies of thirst and dies suddenly at the time of the drought. If there is, on the contrary, a chronic deficiency of water in the soil, com- mencing in the winter before the plant commences to grow, the result is simply a small, weak growth of foliage, insufficient to supply food for the needs of the stem and roots. The roots thus having a restricted food-supply fail to grow with normal vigor and in turn fail to supply the rest of the plant with the soil nutrients which it is their function to collect. We have in this latter case not so much injury from thirst as gradual starvation, which is slower in its action and probably, when several dry seasons follow each other, cumulative, as the reserve food- supply becomes each year more depleted until the plant dies. — 9 — Summary. — This, then, seems to us the true explanation of the death of vines in the Santa Clara Valley, stated in a few words: Slow starva- tion, due to excessive prolonged drought following two exceptionally heavy crops. That some vines have died and others have lived is due, as we have shown, to cooperating influences, the principal of which are the character of the soil, the variety of grape, the age of the vines, and the exhausting effect of late spring frosts in certain vineyards. The objection to the drought theory which has been made, that irri- gated vines have suffered as much as unirrigated, does not appear to be valid, as, in all the cases which we could find, the irrigation was applied too late. Very little irrigation was practiced until 1899, and then only upon the worst vineyards where the vines were already injured beyond redemption. The irrigation to have been effective, should have been given during the winter of 1897-98, the season of greatest drought, and immediately succeeding the two years of abnormally heavy crops. This would have insured the strong growth of foliage during the fol- lowing summer needed to repair the drain of the preceding years and to replenish the depleted stores of reserve food-supply in the trunk and branches. That irrigation was of some value, even when practiced late, is indicated by the record of vineyard B in the foregoing table, which shows that the irrigated portion of the vineyard produced four times the crop per acre produced by the unirrigated portion, though the amount of water used was only about three inches, or just enough to make up for the shortage in rainfall of the year. Young vs. Old Vines. — The immunity of young vines, and of old vines which had been grafted about 1897, is explicable on the theory that they were enabled to withstand the drought because they did not bear in 1897 and were thus saved the drain of that heavy crop. The same reason may account to some extent for the immunity of certain light-bearing varieties. That vines on other soils and in other localities have escaped the destruc- tion that has overtaken the West-side vineyards is due doubtless to the fact that the three destructive factors of drought, heavy bearing, and leachy soil have not elsewhere been so great nor simultaneous. Not Anaheim Disease. — The reasons which have led us to reject as unproven the theory which ascribes the death of the vines to the Anaheim disease are based upon the divergence of the symptoms from those which distinguish that disease as characterized in Bulletin 2 of the Division of Vegetable Pathology of the U. S. Department of Agriculture, entitled " The California Vine Disease/' by Newton B. Pierce. This pamphlet must be considered as the highest authority on this disease, as it is almost the only, or at least the most complete and voluminous, publi- cation on the subject. — 10 — Characteristics of Anaheim Disease. Characteristics Shown by Dying Vines in Santa Clara Valley. Mission more susceptible than Mataro or Zinfandel. Vines in shade of trees less rapidly affected. Grafting the vines does not save them. Cuttings from affected vines which show the disease die as soon as the parent vines. Rotting of the roots is a constant symptom. : Page 141 Mataro and Zinfandel have died more generally than the Mission. Vines near trees have suffered as much 108 or more than others. 138 152 52 All the recently grafted vineyards are healthy. There are many instances in which cut- tings taken during the last two, three, and four years from Mataro and Mis- sion vines which are now dead have been planted, or grafted on phyllox- era-resistant stock, and have now resulted in vigorous, healthy vines. Roots of most of the injured vines are sound. *The numbers refer to pages in the above-mentioned bulletin. To these contrasts should be added the apparent recovery of Grenache vines, which were badly affected last year and this spring, but which in August were making a vigorous healthy growth. Though Mr. Pierce may not make the statement definitely, the impression left, on reading his publications on the Anaheim disease, is that it is cumulative and progressive and that the attacked vines never recover. These contrasts prove either that the Anaheim disease is not the cause of the death of the Santa Clara vines, or that the characteri- zation of the disease as given in the publication above referred to must be profoundly modified to include the symptoms exhibited by these vines. There is, however, no reason at present to suggest the Anaheim disease if, as seems at least very probable, the causes here outlined are sufficient to account for the observed effects. Practical Lessons. — This serious disaster contains two important prac- tical lessons to horticulturists, and especially to vineyardists: First, the necessity of having on hand the means for supplementing a deficient rainfall, even in what are usually considered the non-irrigating districts; and second, the importance of choosing varieties adapted to special locations, soils, and climates. This question of adaptation is particu- larly important to grape-growers who are planting phylloxera-resistant stock, as all the good and thoroughly resistant vines are comparatively limited in their range of adaptability. Wherever new vines are planted in the devastated area it would be extremely unwise to plant any variety which has not well-proved drought-resisting qualities. The resistant vines which have shown the best results so far on the west side of the Santa Clara Valley are Rupestris St. George, Rupestris Martin, and Champini. The last has thriven almost or quite as well as the two — 11 — Rupestris varieties, but unless it shows marked superiority in some other way the others are to be preferred on account of their superior phylloxera-resistant qualities and the greater ease with which they root. The suggestion that Rupestris St. George is resistant to the Anaheim disease is certainly premature when based upon its behavior in the Santa Clara Valley, in view of the fact that the presence of that disease in the valley is more than doubtful, for even Mr. Pierce, the acknowledged authority on this disease, after making an examination of the afflicted vineyards, says in the "California Fruit-Grower" of July 27, 1901, that he "will not express an opinion at this time as to the presence or absence of the California (Anaheim) vine disease in this district." FREDERIC T. BIOLETTI. E. H. TWIGHT.