SEASONAL DISTRIBUTION OF BEMISIA ARGENTIFOLII (HOMOPTERA: ALEYRODIDAE) HONEYDEW SUGARS ON PIMA AND UPLAND COTTON LINT AND LINT STICKINESS AT HARVEST

Authors: HENNEBERRY, THOMAS; JECH, LYNN; HENDRIX, DONALD

Submitted to: Southwest Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Silverleaf whitefly and the associated sticky cotton is a major issue in the textile industry. Sticky cotton occurs as a result of lint contamination with honeydew excreted by whiteflies. Whiteflies occur in most cases in higher numbers on hairy-leaf long-staple cottons then on smooth leaf short-staple cottons. Less then 15% of the cotton acreage in the west is long-staple cotton. For short-staple cotton, 95% of the open bolls occur by the first week in September. Our studies show that defoliation timing can be an important tool to avoid sticky cotton. Extending the cotton season after 95% of the open bolls occur has resulted in the development from non-sticky to lightly sticky cotton within 21 days as measured by increased numbers thermodetector spots and increased amounts of whitefly produced honeydew sugars. Mid-September cotton defoliation could prevent late open boll exposure to whiteflies, and reduce cotton stickiness without compromising yield.

Technical Abstract: Whitefly populations were higher on long-staple Pima S-7 cotton compared with short-staple, upland cottons, Deltapine (DPL) 50 and 5415 in 1995 and DPL 50 in 1996. Higher numbers of mature open cotton bolls occurred earlier for DPL cultivars compared with Pima S-7. Also, numbers of open bolls for DPL cotton bolls peaked 8 to 14 days before Pima S-7 and decreased dramatically by 15 September reflecting termination of the first fruiting cycle in August. For Pima S-7, numbers of open bolls per week declined gradually after the peak without a clear cut termination occurrence. Trehalulose and melezitose sugars produced by Bemisia were found on lint for all weekly samples in both years for both cotton types. About 95 and 80% of the open cotton bolls, of the Deltapine and Pima S-7 cottons, respectively, occurred by mid-September. For upland cotton in 1996, extending the cotton season after 95% of the crop matured resulted in ndevelopment from non-sticky cotton to lightly-sticky cotton within 21 days after 15 September. This could have been avoided with mid-September defoliation. Later fruiting and lack of a distinct end of the first cotton fruiting cycle probably precludes using defoliation for long-staple Pima cotton. Except in one instance, thermodetector counts and lint, trehalulose and melezitose content for all sampling methods were significantly correlated.