ABSTRACT
In 1984 and 1985 we developed an egg sampling plan for the pink bollworm (PBW), Pectinophora gossypiella (Saunders), to provide a more accurate index of moth (target stage) activity than conventional larval sampling. The plan requires that only the presence or absence of eggs laid on bolls be determined to decide when insecticide treatments are needed. Our objective in 1986 was to determine whether egg sampling vs. conventional treatment criteria ( e.g., larval infestations, trap catches of male moths, and/or fixedspray intervals) provided more optimal timing of insecticide applications in a 640 ac. field test. The 1986 test consisted of 16 commercial fields, ca. 40 ac. each, in the Palo Verde valley, CA.Of the 16 fields, 8 were treated based on egg sampling using a treatment action level of 6-8% infested bolls. The remaining 8 fields were treated based on the conventional methods listed above. Implementation of the egg sampling method resulted in an average 35 percent seasonal reduction in insecticide use when compared to conventional methods. Despite the reduction in insecticide use, PBW larval infestations were not significantly different (P>0.40) in fields sampled for eggs vs. fields sampled for larvae from June to September. Yields were also not significantly different (P>0.40) between the two sets of fields. The economic benefit of a 35 percent reduction in insecticide use is discussed.
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