Insecticidal Dusts: Grain Protectants During High Temperature-Low Humidity Storage2

Abstract

Diatomaceous earth dusts impregnated with 4.5, 6.0, and 7.5 ppm AI pirimiphos-methyl and with 5.0, 7.5, and 10 ppm AI malathion were tested as protectants against insect attack on hard winter wheat (11.2% moisture) stored at ca. 33.4°C and 40% RH. The dusts were applied at a rate of 0.5 kg dust/metric ton of wheat. Sprays prepared from emulsifiable concentrates and the dust base alone were used for treatment checks. Dust formulations were more effective than sprays that contained equivalent doses and were much more effective were than diatomaceous earth alone. Pirimiphos-methyl was more effective than malathion.