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Evaluation of Thrips Damage on Maturity and Yield of Virginia Cotton

D. Ames Herbert, Jr.


Visual plant damage ratings, PMAP plant mapping techniques and yield measurements were used to evaluate the impact of selected insecticide treatment options on thrips damage to cotton seedlings, plant growth and yield. All experiments were conducted at Virginia Tech's Tidewater Agricultural Research and Extension Center in Suffolk, VA. Treatments included: selected in-furrow applied or seed treated insecticides, both with and without an additional foliar insecticide band at true leaf stage; foliar applied insecticides, alone; and Command herbicide safening insecticides. Insecticides included selected organophosphates and carbamates, and imidacloprid and spinosad. Thrips populations were considered high during the first few weeks after plants emerged and damage to seedlings reached extreme levels in untreated controls. This combined with the additional stresses caused by unusually cool early season weather and later-season dry weather resulted in retarded plant growth. All treatments reduced thrips damage, and in most cases, the reduction was significant. PMAP data indicated that all treatments allowed plants to mature faster than plants in untreated control plots. Treated plants were taller and had more squares, green and open bolls on most evaluation dates. Most importantly, all treatments resulted in significantly higher lint yields compared with untreated controls. The yield increase over that produced by the untreated controls, averaged over all experiment treatments, was 380 lb lint/acre. Specific treatments and comparisons are discussed.

Reprinted from Proceedings of the 1998 Beltwide Cotton Conferences pp. 1177 - 1180
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998