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This article in CS

  1. Vol. 19 No. 6, p. 861-863
    Received: May 21, 1979

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Chemical Plant Growth Suppressants for Reducing Late-Season Cotton Bollworm-Budworm Feeding Sites1

  1. R. O. Thomas,
  2. T. C. Cleveland and
  3. G. W. Cathey2



Late-season vegetative and reproductive growth on cotton (Gossypium hirsutum L.) plants contributes little to yield, but provides feeding sites for diapausing insects. Increased numbers of damaging insects result the following season and require intensified control measures. The objective of this research was to evaluate the effect of plant growth suppressants on feeding sites and fall populations of Heliothis spp. Various combinations of chlorflurenol (methyl 2-chlor-9-hydroxyfluorene-9-carboxylate) and TD-1123 (potassium 3,4-dichloroisothiazole-5. carboxylate) were applied during late August and early September of 1977 and during early September of 1978. Evaluations were made of insect feeding sites (leaves, squares, and small bolls) in plant terminals, and of bollworm (Heliothis zea Bobbie) or tobacco budworm (H. virescens F.) larvae and eggs 15 to 25 days after treatment. The chemicals were more effective when applied either as a mixture or in sequence than when used alone. In 1977, feeding sites and bollworm eggs in sequentially treated plots were reduced 50% or more when compared with the control. In 1978 feeding sites were reduced an average of 85% and larval and egg populations reduced an average of 64% at five locations in plots treated with both chemicals. Lint yield in most chemically treated plots were reduced, but not significantly except at two locations where reductions occurred at the 10% level of probability; average reduction for all locations was 8.6%. This research indicates that plant growth suppressants can be used effectively to reduce late-season vegetative and reproductive growth and provide benefits in bollworm-budworm control.

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