Chemical Control of the Sunflower Moth on Sunflowers1

Abstract

Tests were conducted to determine the effectiveness of 9 insecticides for control of Homoeosoma electellum (Hulst). Tests at College Station, Texas, showed that 2 applications of methyl parathion, endosulfan, diazinon, and malathion reduced the number of larvae and increased yields. Tests at McGregor, Texas, showed that only endosulfan and carbaryl reduced the larval infestation following 1 application; however, they did not increase yields. Two applications of GS-13005, (O,O -dimethyl phosphorodithioate Sester with 4-(mercaptomethyl)-2-methoxy-∆2-1,3,4-thiadiazolin-5-one), azinphosmethyl, methyl parathion, carbaryl, azinphosmethyl ultra-low-volume (ULV) and methyl parathion ULV increased yields. Plots treated 3 times, except those treated with malathion ULV, had lower infestations than the check plots and yields were increased except when treated with trichlorfon. Yields were significantly increased when methyl parathion, endosulfan, or carbaryl were applied at 5-day intervals. Applications at pre-flower, or at 10% flower, in most cases, did not significantly reduce the number of larvae or increase seed yields. Generally, insecticides applied at the 50 and 100% flower stages were most effective.