February, '22] parrott: dusts FOR sucking insects 83 



The Currant Aphis 



Dusting and spraying experiments with the currant aphis {Myzus 

 rihis Linnaeus) were conducted in a planting of 500 currant bushes, 

 which provided for 100 plats of 5 plants each, thus permitting frequent 

 tests of the different materials. The spraying mixture was composed of 

 1 pint of nicotine sulfate to 100 gallons of water to which were added 6 

 pounds of soap. The dusting preparations contained 0.50, 1.00, and 

 2.0 per cent nicotine, respectively, sulfur-lead arsenate (90-10) being 

 used as the carrier of the nicotine. Each plat received three treat- 

 ments, dusting material being applied at the rate of 1 pound per bush, 

 and the spraying mixture at the rate of 2 gallons per bush. 



Both dusting and spraying mixtures afforded efficient protection. 

 All the treated plants contrasted strongly with the untreated plants, 

 which displayed nimierous discolored and distorted leaves that began 

 to drop during midsummer. The foliage of the treated plants was 

 more abundant and adhered to the plants long after the checks had 

 been completely defoliated. 



The dusting preparations showed a high rate of toxicity to the currant 

 aphids. The condition of the foliage containing 0.5 per cent nicotine 

 was not quite as satisfactory as that of the vines dusted with prepara- 

 tions containing 1 and 2 per cent nicotine, respectively. A small 

 percentage of the leaves showed injury, but the curling was not of the 

 severe type exhibited by the checks, and there was little, if any, prema- 

 ture defoliation. 



The Cabbage Aphis 



The experiments with the cabbage aphis {Aphis hrassicae Linnaeus) 

 provided for tests with dusting and spraying mixtures with different 

 ratios of nicotine, in which all available types of machines for applying 

 liquid and powdered insecticides were used. Soap and nicotine at 

 standard strength, sulfur-lead arsenate (90-10) and lime dusts, con- 

 taining 0.5, 1.0, and 2.0 per cent nicotine respectively, were toxic to the 

 cabbage aphis. Two applications gave excellent control, resulting in 

 yields of cabbage which were from 4 to 6 tons per acre according to the 

 kind of treatment in excess of those of the check plats. 



From the standpoint of economy and effectiveness, the most satis- 

 factory treatment was a lime preparation (calcium hydrate) containing 

 2.00 per cent nicotine, applications being made at the rate of 20 pounds 

 per acre with a ' ' hand bellows duster. ' ' With power dusting machinery, 

 from 35 to 40 pounds of material were required to secure effective 

 control. Considering the results as a whole, dusting appears to be 

 a very promising system of treatment for controlling the cabbage 



