Research on Area wide Stalk Destruction for Cultural Control of Boll Weevil in the Lower Rio Grande Valley

K.B. Summy, W.G. Hart, J.R. Cate, and D. Bar


 
ABSTRACT

Research conducted in the Pao Grande Valley (LRGV) of Texas during 1980-1984 has implicated poor cotton stalk destruction as a major causal factor in chronic outbreaks of boll weevil, Anthonomus grandis Bohmm. An aerial surveillance system based on high-altitude color infrared photography enabled the achievement of a 98% reduction in the abundance of illegal cotton regrowth between 1982 (ca. 27,000 ac) and 1983 (ca. 750 ac). Densities of colonizing adult weevils declined to undetectable levels on commercial cotton in areas where early destruction was practiced but remained at typically damaging levels (21-240 adult weevils/ac) in areas of moderate to poor stalk destruction. The distribution of first-generation immature weevils along a 7-mi. transect during the 1984 production season was artery described by the power function y = 516.8x(-1.75) where y = weevil density/ac and x = distance (in mi.) from a 5-ac field of cotton plowed during November 1983. Pheromone traps situated in the immediate vicinity of late-plowed cotton trapped significantly, greater numbers of adult weevils and contained significantly higher ratios of teneral (newly-emerged) adults than did comparable traps in areas where early stalk destruction was practiced. This suggested the possibility that weevils were emerging through soil from buried cotton refuse. In tests where known-numbers of squares containing late stage larvae or pupae were buried at increments of 0.5 cm to 20 cm in saturated clay-loan soil in the field, emergence of adults ranged from 44% of those buried at 5.0 cm to 1.8%, of those buried at 20.0 cm. The emergence data fit the exponential model y = 127.5e(-0)(.22x) where y = percentage emergence and x = depth of burial. These results suggest that weevil reproduction on illegal cotton regrowth during the period September-February constitutes a principal source of damaging weevil infestation on LRGV cotton, a problem which may be greatly aggravated by prolonged emergence of weevils from late-plowed infested cotton refuse.



Reprinted from 1985 Proceedings: Beltwide Cotton Production Research Conferences pg. 145
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998