Seed and soil treatment with systemic insecticides to prevent aphid colonization of emerging beet seedlings

Dimefox at 2 lb. or diethyl ethylthiomethyl dithiophosphate (Thimet) at 1 lb. applied at drilling in 100 gal. water along the drills, or seed treated at rates giving 6-8 oz. Thimet or 8-24 oz. diethyl ethylthioethyl dithiophosphate (Disyston) per acre?, made sugar beet seedlings toxic to aphids up to 30 days after sowing four root crops in April-May, and up to 30-40 days after sowing five steckling crops in autumn. Malathion, demeton, demeton methyl, bis (dimethylamino) azido phosphine oxide (N.C.7) and schradan were less effective. The infestation of green aphids was decreased by the treatments during what is often a critical period for virus infection in summer-sown stecklings and occasionally in spring-sown root crops. Germination was 73-100% of the control after soil treatments, 91-98% after Disyston seed treatments and 62-84 % after Thimet seed treatments. The treatments slightly decreased Aphis fabae injury to steckling seedlings in 1955 and the number of plants with yellows in a steckling experiment in 1956.