Timing of Insecticidal Applications for Control of the Pink Bollworm1

Abstract

In tests at Phoenix, Ariz., 3 insecticide-timing schedules were compared on long-staple cotton in 1967 and 2 schedules were compared on short-staple cotton in 1968 for control of Pectinophora gossypiella (Saunders). Timing treatments in 1967 consisted of 1 schedule initiated against an early-square infestation on June 21, another initiated on July 12 when 8% of the early boll-set was infested, and the last, begun Aug. 8 when 18% of the bolls were infested. Once started, the respective schedules were continued at 5 to 6 day intervals until the test was terminated on Sept. 30. Two insecticides, azinphosmethyl and carbaryl, were compared on each schedule. All 3 schedules resulted in a comparable degree of pink bollworm control and in comparable yields; all resulted in significantly lower pink bollworm infestations and increased yields when compared with the untreated check. There was no difference between the 2 insecticides in control of the pink bollworm or yields obtained. The 1968 insecticidal treatments consisted of a rigid automatic schedule which was initiated after 20% of the bolls became infested and I which was initiated at the same time but where applications were deleted as the infestation was reduced appreciably below the 20% level. Azinphosmethy] and Azodrin® (3-hydroxy- N -methyl- cis -crotonamide dimethyl phosphate), applied at the rates of 0.75 and 0.94 Ib per acre, respectively, were compared on each schedule. Both schedules significantly reduced boll infestations. However, when 3 applications Were deleted from the nonautomatic schedule a rapid increase of the pink bollworm infestation occurred. Yields from the 2 schedules were quite similar and only slightly higher than those from the untreated check. Both insecticides, regardless of schedule, were equally effective.