Insecticide Evaluation on Squaring Cotton in the Greenhouse for Control of Bollworms and the Beet Armyworm

J.N. All, T.M. MitChell, B.H. Tanner, and P.M. Roberts


 
ABSTRACT

Using greenhouse trials on squaring cotton plants can reduce the time and expenses required to evaluate insecticide efficacy on pests. Cotton was grown in pots to squaring stage and sprayed in a greenhouse with a rotating boom sprayer designed to simulate field application of insecticides. The treated plants were placed in large stainless steel trays that were flooded with water to irrigate plants from below and to prevent larvae from moving between the plants. The cotton was infested twice per week by placing freshly hatched bollworm (Helicoverpa zea (Boddie) and Heliothis virescens (Fabricius)) larvae on the bracts of squares or by applying first, second and third instar beet armyworm Spodoptera exigua (Hubner)) larvae on the leaves. After four weeks the treated plants were examined for the amount of defoliation, number infested, uninfested and aborted squares and the number of surviving larvae. Test results with bollworms using new strains of Bacillus thuringiensis Berliner showed similar relative performance of the materials in the greenhouse test as compared to their average seasonal efficacy in field tests. Greenhouse results with the beet armyworm using a variety of contact and stomach insecticides showed a similar range of efficacy as occurs in the field.



Reprinted from 1992 Proceedings Beltwide Cotton Conferences pp. 914 - 915
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998