ABSTRACT

Chemigation of non-emulsifiable concentrate (EC) oil and water mixtures of cypermethrin, sulprofos, thiodicarb and Bacillus thuringiensis Berliner var. kurstaki to field grown cotton was evaluated for effectiveness against larvae of the bollworm, Helicoverpa zea (Boddie). All tested insecticide mixtures could be readily applied using chemigation technology. Both tested rates (0.06 and 0.03 kg ai/ha) of cypermethrin (Ammo 2.5) mixed with oil and the high rate (0.06 kg ai/ha) of cypermethrin mixed with water consistently resulted in the greatest bollworm mortality through the first 72 hours following treatment. Plants treated with the above cypermethrin mixtures yielded significantly greater amounts of seed cotton than plants treated with any other tested insecticide. In most instances the addition of a non-EC oil to chemical insecticides resulted in greater levels of bollworm mortality than chemical insecticides mixed with water 24 h after application. However, addition of oil to B. thuringiensis appears to limit its effectiveness.