Effectiveness of Several Insecticides against the Boll Weevil, Bollworm, and Cotton Leafworm

In small-plot experiments at Florence, S. C., against the boll weevil (Anthonomus grandis Boh.), Guthion-DDT, Thiodan, methyl parathion-DDT, EPN-DDT, and endrin dusts gave comparable control and yields. Sprays and dusts of Guthion and endrin and a spray of Dipterex were equally effective. Guthion- DDT spray gave significantly better control and yield than toxaphene and heptachlor-DDT sprays. Sprays of Guthion-DDT, Dipterex-DDT, methyl parathion-DDT, EPN-DDT, and endrin gave comparable control and yields. Dusts of Sevin, malathion, Guthion-DDT, and endrin gave comparable control. Sprays and dusts of Guthion, malathion, and endrin were equally effective. In a spray malathion was more effective at 2 pounds per acre than at 1 pound. Malathion plus endrin was more effective than endrin alone. Sprays of Sevin, Thiodan, endrin, toxaphene with and without methyl parathion, and methyl parathion gave comparable control. Against the bollworm (Heliothis zea (Boddie)) malathion dusts were ineffective. Against the cotton leafworm (Alabama argillacea (Hbn.)) methyl parathion, malathion, and Guthion were more effective than BHC, endrin, and toxaphene. In field-cage experiments against the boll weevil, malathion and methyl parathion gave consistently high 24-hour mortalities. Combinations of malathion with endrin or toxaphene were usually more effective than endrin or toxaphene alone. Guthion was more effective than toxaphene and BHC. Thiodan was less effective than endrin. Sevin at 2 pounds per acre gave high 48 hour kills. Monsanto CP-7769 and Chipman R-6199 were comparatively ineffective. Malathion was residually more effective than endrin, methyl parathion, or Thiodan.