250 THE MONTHLY BULLETIN. 



COMBINATION SPRAYING EXPERIMENT FOR THE CON- 

 TROL OF MILDEW AND LEAF HOPPERS ON 



GRAPE VINES. 



By S. W. Foster, San Francisco, Cal. 



Grape mildew and vine hoppers are well known to California grape 

 growers. Mildew has caused injury and consequent loss since the 

 beginning of the grape industry in this State. Vine hoppers, sometimes 

 erroneously called vine thrips, have been gradually increasing in 

 numbere for some time and, during recent years, have destroyed a 

 large percentage of the crop in many vineyards. The loss is especially 

 heavy on table grapes, both in destruction of foliage, weakening the 

 vine and rendering the grapes unmarketable. 



The Avriter, in conjunction with Mr. R. M. Roberts, agricultural 

 demonstrator for the Atchison, Topeka and Santa Fe Railway Company, 

 and Mr. F. P. Roullard, horticultural commissioner of Fresno County, 

 undertook, in 1914, a definite set of experiments to ascertain a feasible 

 means of controlling both vine hoppers and mildew under California 

 conditions. Mr. Tyler of the Experiment Station of the University of 

 California spent considerable time in taking notes and making extended 

 counts for details of the results obtained by these experiments. 



Most of this work was done in the vineyard of Mr. T. H. Jack at 

 Parlier, Fresno County, who furnished a good power spray machine 

 built especially for vineyard work, also the labor and most of the 

 materials used. Large Muscat and Emperor vines, some of which were 

 twenty-seven years old, were used for the experimental work. Each 

 block or experiment consisted of the number of vines that could be 

 sprayed with one tank (200 gallons) of spray; this varied from 200 to 

 300 vines for each tank. The spraying was done as soon after blooming 

 as it was thought safe to disturb the fruit clusters. Nymphs of the vine 

 hoppers were abundant; several counts made showed that an average 

 of at least 100 hoppers were present on each leaf. No hoppers had 

 reached the winged or adult stage at this time, but many had well 

 developed wing pads giving a goodly number of nymphs from prac- 

 tically full grown to recently hatched young. Also there were many 

 eggs present in the leaves and winged adults, capable of depositing more 

 eggs, were numerous among the vines. The foliage was fast becoming 

 mottled and of a silvery color as a result of the injury caused by these 

 insects. No noticeable injury has been caused to the vines by mildew 

 up to this time. Spraying commenced May 22, 1914, normal fair 

 weather conditions prevailing at that time. 



FORMUL/E USED IN SPRAYING. 



The experiments included th(^ use of different combinations as follows: 



Experiment No. 1— Atomic sulphur paste 24 pounds 



Muscat vines. Black leaf "40" 1 pint 



AVater to make 200 callous 



Experiment No. 2— Atomic sulphur paste 24 pounds 



Muscat vines. AVater to make 200 gallons 



Experiment No. 3— Atomic sulphur paste 24 pounds 



Muscat vines. Black leaf "40" ^ pint 



AVater to make 200 gallons 



Experiment No. 4 — Atomic sulphur paste 24 pounds 



Large Emperor vines. Black leaf "40" 1 pint 



Fish glue 2 pounds 



Water to make , ^ 200 galloqs 



