402 Report of the Department of Entomology of the 



The middle section and the small plat marked "a" (Chart 2) were 

 sprayed with homemade fish-oil soap, 1 lb. to 5 gallons of water, while 

 the remainder of the plats and the section marked "b" were sprayed 

 with insecticide soap, 1 lb. to 3| gallons of water. All plats were 

 twice sprayed as follows: A strip about 12 ft. wide was sprayed 

 across each bed, then resprayed immediately before starting on 

 another strip, and so on until each section was sprayed. From the 

 experiments that were conducted, it was estimated that on an average 

 approximately 200 gallons of mixture would spray one acre twice. 

 On this basis, without including labor, " Black Leaf 40," used 1 

 gallon to 200 gallons of water, would cost $12.00; insecticide soap, 

 1 lb. to 3| gallons water, would cost $5.40; resin-potash soap, 1 lb. 

 to 3^ gallons water, would cost $2.00. 



Results on trisects and plants. — Without resorting to an actual 

 count of the numbers of dead and living insects, it appeared that 

 this method of spraying did not give as marked results as the one 

 followed on July 11 where a longer interval of time was allowed 

 between each application. The explanation for this marked dif- 

 ference in results is not clear. Apparently the effect of the first 

 application was to force a good many of the insects into the tops 

 of the vines, where they would be more quickly dried by the sun 

 and the air. If sufficient time was allowed, many of the insects 

 would occupy positions which would render them quite exposed to 

 the second treatment. Then, moreover, it proved a difficult matter 

 to do thorough spraying. In some instances it was almost impossible 

 to reach all of the young nymphs feeding on the undersides of the 

 branches, as the heavy growth interfered with the spray, preventing 

 complete wetting of the foliage and wood. 



Early in September, it was discovered that wherever the soap 

 solutions were used stronger than 1 lb. to 7 gallons of water, not 

 over one-third of the berries were perfect. Of the affected berries 

 very few were shriveled or showed injury to one side. In most cases 

 they were dwarfed, as shown in Plate XVIII, fig. 1, a; b is normal 

 fruit collected one foot from the sprayed section. Another character- 

 istic of the soap-treated sections appeared later in the plants them- 

 selves. As the vines took on a natural reddish tinge late in the fall, 

 the sprayed sections remained dark green as if recently given an 

 application of nitrate of soda. It appeared that the vines bearing 

 stunted fruit had put all their energy into a new growth of wood 

 instead of fruit. 



