UNIVERSITY OF CALIFORNIA AGRICULTURAL EXPERIMENT STATION BENJ. IDE WHEELER, PRESIDENT COLLEGE OF AGRICULTURE THOMAS FORSYTH HUNT> Dean anq D|rector nrnuri c"w H. E. VAN NORMAN, Vice- Director and Dean btKI\tLtY UNIVERSITY FARM SCHOOL CIRCULAR No. 126 March, 1915 SPRAYING FOR THE GRAPE LEAF-HOPPER BY H. J. QUAYLE Injury. — The grape leaf-hopper (Typhlocyba comes, Say.) is, at the present time, probably the most important insect pest of the vine in California. While greater actual damage has been done to the vine- yard interests by the phylloxera, this injury is largely past because of the replanting on resistant stock in most sections where the phyl- loxera was formerly destructive. The injury by the grape leaf -hopper, on the other hand, has really increased because of the greater acreage planted, which has favored the increase of the insect. Leaves with a mottled aspect of gray and green are the first indi- cation of hopper injury. As the feeding continues, the whole surface of the leaf becomes at first silvery, and later yellow and brown, when it finally drops from the vine. Leaves thus affected occur most com- monly about the crown of the vine, though in cases of severe injury nearly all the leaves will show this effect. Many of the leaves may drop off or become functionless, as early as June or July, and this loss of foliage prevents the berry from maturing properly. The lack of full foliage to the end of the season also prevents the canes from ripening normally for next year's wood. The buds fail to develop in the following spring, and thus the vine may be more or less per- manently stunted in growth in severe cases of hopper injury. While injury as above described occurs in some sections or some vineyards nearly every year, such injury does not occur universally. It is only when the hoppers become excessively numerous that enough injury is done to warrant treatment. Distribution. — The grape leaf -hopper occurs in numbers sufficient to be a pest only in the Sacramento, San Joaquin and Imperial valleys. It rarely becomes injurious in the coast valleys or the grape sections in Southern California, aside from the Imperial and the Coachella valleys. Seasonal History. — The grape leaf-hopper passes the winter as an adult insect, which may feed on various plants growing in the vine- yard or vicinity during the warmer weather. During cold or wet weather, it remains under leaves or rubbish, or low down on the growing plants on which it feeds. When the vine comes into leaf in the spring, the hopper leaves its varied winter food plants and feeds exclusively on the grape leaves until they fall in the autumn. The young hoppers or nymphs begin to hatch about May 1st in the Fresno section, a little later in the Lodi and Stockton sections, and two or three weeks earlier in the Imperial Valley. The eggs require from eight to twelve days to hatch, and eighteen days are required to bring the young to maturity. About one hundred eggs are laid by each female. The young of the first generation begin appearing in May, and the young of the second generation in the latter part of June. There are thus two generations of the hopper in a season. Control of the Overwintering Adults.— Turning sheep into the vineyard in the fall to eat the leaves results in causing the hoppers to go to their winter food plants a little earlier, and also deprives them of shelter in the accumulation of leaves in the vineyard. A clean vine- yard in the winter season has fewer hoppers than one in which there are more or less green growth and bunches of dry grape leaves. Plowing in the early spring and turning under the green growth and dry leaves does not destroy the hoppers, but does drive them to the borders or to neighboring fields. The result then of both sheeping and early plowing is to drive the hoppers elsewhere for food and shelter, but there is no assurance that many of these will not return to the vineyard when the vines come into leaf. A few may be destroyed or starved, and the efficiency of such a practice as plowing and sheep- ing will depend largely upon how generally it is carried out in a district. To kill the overwintering hoppers either during the winter or in the spring when they first come onto the vines, and thus destroy them before they multiply and do damage would be the best solution of hopper control. Thus far, however, no generally satisfactory method for such control has been found. A three-sided screen box operated to capture the adults on the vines when the shoots are six to eight inches long has been used with success in many cases, but it is not satisfactory for all styles of vine pruning, and involves too much hard labor to suit many California vineyardists. Experiments carried on last spring in spraying into a canvas canopy attached to the spray- rig failed to kill a sufficient percentage of the adult hoppers. By this apparatus the vine and the whole interior of the canopy was thoroughly charged with the spray, but the winged hoppers proved to be too resistant to any of the materials that could be used with safety to the vine. In view of these objections to the control of the adult hoppers, spraying for the young or nymphs was carried on later in the season Spraying for the Nymphs or Young. — As will be noted above, the adult hoppers are almost impossible to kill with a spray ; on the other hand, the young are very readily killed by a proper spray. The chief difficulty is to get the spray on the under side of all the leaves where the hoppers are, and there is the further objection that many of the eggs which are within the tissues of the leaf, as well as the adults, which are also present, are not affected by the spray. In spite of these drawbacks, however, spraying for the nymphs will pay when the hoppers are excessively abundant. The destruction of the young greatly reduces the number already present, as well as the succeeding generation. Materials. — A number of different sprays were tested, but only the one found most satisfactory will be discussed here. The spray found most efficient in killing the young, as well as most neutral to the grape foliage and berry, was blackleaf 40 per cent and soap in the following amounts : Blackleaf 40% 1 pint Liquid soap % gallon or Hard soap 2 pounds Water 200 gallons If liquid soap can be procured, it obviates the necessity of heating. The hard soap, preferably whale-oil, is cut in thin slices and dissolved in hot water. Where soap is added to the blackleaf the spray carries and spreads better, but too much soap should not be used or a spotting of the berries will occur. Equipment. — A power sprayer is very desirable for hopper spray- ing, though if the acreage be small a hand pump will suffice. In our work last season a large capacity orchard sprayer was used, as well as a smaller vineyard sprayer, as shown in figure 2. Since the ground is usually freshly plowed at the time of spraying, too heavy an outfit is not desirable, and a short-turning truck is needed. A supply wagon for carrying materials and water to the sprayer in the field is econ- omical. Whatever kind of spray outfit is used, it will be found con- venient to take several rows at a time and to do this an extension of the hose above the vines is necessary. In the figure an improvised arrangement is seen which simply supports the spray hose. In the place of this a gas-pipe extension may be employed with connections for the spray hose between every alternate two rows. The most satisfactory type of nozzle is an angle nozzle with no plunger or other addition to catch among the canes. An angle Bean mist or whirlpool, or a Friend " Drive" spray nozzle is suitable. One of these nozzles, or two if desired, is attached to a rod but four feet long. The ordinary eight or ten foot rods for orchard spraying cannot be used with satisfaction in a vine- yard. Applicatio n. — Since the young hoppers are on the under side of the leaves entirely, the spray must be directed from below. It is not necessary to spray the upper sides of the leaves. The spray will kill no more hoppers than are hit so that the results will depend upon the thoroughness with which the application is made. Time of Application. — One of the most important factors in hopper spraying is the time of application. If the spray is ap- plied too early, too many eggs which have not yet hatched will escape because the spray cannot reach them; if too late, many young will have become adult- winged hoppers which cannot be killed, and these will later de- posit their full quota of eggs. For the Fresno section in average years, the time for hop- per spraying will be from May 20 to about June 10. The criterion to go by for each year and locality is to begin spraying (L **—> 0* . m • ■- m n ' ^* <*&*** 1 i : 'mm ' <±) +J 5 '■- i / ^ ^ ® £ va ymp eren he d : ShO P e five n the diff is in t he stage V ■' \ rj «H ^ "^ 1 s|§ i— 1 t» t> f_ . © +J OQ bp >■ fl m "H -iH S ^ ?Wi& «3 s % > o t* © ^ ily u i^\ as soon as some of the nymphs are in the last stage as shown in figure 1 on the extreme right. The wing-pads, the projections extend- ing down the sides of the body, are shown to be of considerable length in this stage. They extend to the fourth ring of the abdomen. After five days in this stage, they emerge with fully developed wings. Such hoppers with fully developed wings cannot be killed by the spray. Cost. — On account of the smaller returns per acre of grapes as compared with some of the tree fruit crops, the cost of any control work to be practicable must be kept as low as possible. The following figures will show that spraying for the hoppers is not exorbitant, especially when the hoppers are extremely abundant and the con- sequent benefit to the fruit and vine is taken into consideration. The two outfits used by Mr. P. H. McGarry at Clovis consisted of a IV2 H. P. Bean engine pump with three fifty-gallon barrels mounted on a wagon truck. There were four lines of hose per outfit and a single small nozzle throwing a fine mist spray on the end of each rod. Such an outfit costs about $165. There were five men in the crew, one team- ster and four nozzle men. One of these outfits sprayed about 4500 vines per day (545 vines per acre) or 8.22 acres per day. The vines were seven-year-old Malagas, and the amount of spray per vine was approxi- mately one quart. This spraying, including labor and materials, cost from $2.50 to $4.50 per acre. s Materials Blackleaf 40%, 1 pint $ 1.56 Whale-oil soap, 2 pounds at $.06 12 Cost of material per 200 gallons of spray $ 1.68 Labor 1 man and team $ 4.50 4 nozzle men at $2.00 8.00 Cost of labor per day $12.50 On Mr. J. H. Jack's place at Parlier, a Bean Giant Duplex 2% H. P. outfit with a tank holding two hundred gallons was used. Mr. Jack estimated that with one teamster, two nozzle men, and an extra team and teamster for a supply wagon, he could spray 10 acres per day at a cost of $3.30 per acre. The vines on this place were twenty- four-year-old muscats but were about the same size as the seven-year- old Malagas on Mr. McGarry 's place. In most of the spraying on Mr. Jack's vines, about two-thirds of a gallon per vine was used, and it requires about this amount for good work on that size of vine. On the basis, therefore, of two-thirds of a gallon per vine for twenty-four-year-old muscats or eight or ten-year-old Malagas, and counting 500 vines per acre, the amount of material required to spray 10 acres would be as follows : 5,000 vines at % gallon 3, 333% gallons of spray Blackleaf 40% at 1 pint to 200 gallons 16% pints or about 2 gallons Whale-oil soap at 2 pounds to 200 gallons 33 % pounds Fig. 2. — A vineyard sprayer used in spraying for the grape leaf-hopper. The temporary support of the hose may be replaced by gas-pipe extension with hose connections. The cost of the above material for 10 acres would be as follows : Blackleaf, 40%, 2 gallons at $12.50 per gallon $25.00 Whale-oil soap, 33% pounds at $.06 per pound 2.00 Total cost materials for 10 acres $27.00 When the materials are purchased in quantity, the cost should be less than is indicated above. STATION PUBLICATIONS AVAILABLE FOR DISTRIBUTION REPORTS Appendix to Viticultural 1897. Resistant Vines, their Selection, Adaptation, and Grafting Report for 1896. 1902. Report of the Agricultural Experiment Station for 1898-1901. 1903. Report of the Agricultural Experiment Station for 1901-03. 1904. Twenty-second Report of the Agricultural Experiment Station-for 1903-04. 1914. Report of the College of Agriculture and the Agricultural Experiment Station, 1913-June, 1914. July, No. 168. 169. 170. 174. 177. 178. 182. 183. 184. 185. 195. 197. 198. 203. 207. 208. Observations on Some Vine Diseases in Sonoma County. Tolerance of the Sugar Beet for Alkali. Studies in Grasshopper Control. A New Wine-Cooling Machine. A New Method of Making Dry Red Wine. Mosquito Control. Analysis of Paris Green and Lead Arsenate. Proposed Insecticide Law. The California Tussock-Moth. Report of the Plant Pathologist to July 1, 1906. Report of Progress in Cereal Investi- gations. The California Grape Root-worm. Grape Culture in California ; Improved Methods of Wine-making; Yeast from California Grapes. The Grape Leaf-Hopper. Report of the Plant Pathologist to July 1, 1909. The Control of the Argentine Ant. The Late Blight of Celery. BULLETINS No. 211. 212. 213. 216. 225. 227. 230. 234. 240. 241. 242. 243. 244. 245. 246. 248. 249. 250. How to Increase the Yield of Wheat in California^ Califoprfa White Wheats. ThgCPrinciples of Wine-making. A Progress Report upon Soil and Climatic Factors Influencing the Composition of Wheat. Tolerance of Eucalyptus for Alkali. Grape Vinegar. Enological Investigations. Red Spiders and Mites of Citrus Trees. Commercial Fertilizers. Vine Pruning in California. Part I. Humus in California Soils. The Intradermal Test for Tuberculosis in Cattle and Hogs. Utilization of Waste Oranges. Commercial Fertilizers. . Vine Pruning in California. Part II. The Economic Value of Pacific Coast Kelps. Stock Poisoning Plants of California. The Loquat. No. 65. 68. 69. 70. 76. 79. 80. 82. 83. 84. 87. 88. 100. 101. 102. 106. 107. CIRCULARS No. The California Insecticide Law. 108. The Prevention of Hog Cholera. 109. The Extermination of Morning-Glory. Observations on the Status of Corn Growing in California. 110. Hot Room Callusing. 111. List of Insecticide Dealers Boys' and Girls' Clubs. 113. The Common Ground Squirrels of 114. California. 115. Potato Growing Clubs. 116. Mushrooms and Toadstools. 117. Alfalfa. Advantages to the Breeder in Testing 118. his Pure-bred Cows for the Register 119. of Merit. 120. Disinfection on the Farm. Infectious Abortion and Sterility in 121. Cows. Pruning Frosted Citrus Trees. 122. Codling Moth Control in the Sacra- mento Valley. 123. The Woolly Aphis. Directions for using Anti-Hog-Cholera 124. Serum. 125. Spraying Walnut Trees for Blight and Aphis Control. Grape Juice. Community or Local Extension Work by the High School Agricultural De- partment. Green Manuring in California. The Use of Lime and Gypsum on Cali- fornia Soils. Correspondence Courses in Agriculture. Increasing the Duty of Water. Grafting Vinifera Vineyards. Silk Worm Experiments. The Selection and Cost of a Small Pumping Plant. The County Farm Bureau. Winery Directions. Potato Growing in the San Joaquin and Sacramento Deltas of California. Some Things the Prospective Settler Should Know. The Management of Strawberry Soils in Pajaro Valley. Fundamental Principles of Co-opera- tion in Agriculture. Alfalfa Silage for Fattening Steers. Aphids on Grain and Cantaloupes.