Introduction:
During the last 10 years, the cotton aphid (Aphis gossypii) has developed from a non-pest to one of the most significant insect pests of California cotton. For instance,in1997, cotton aphid outbreaks were severe and an estimated 3.5% yield loss occurred despite -$40/acre control costs which were incurred. Cotton aphid infestations during the mid-season (July to mid-August) reduce cotton lint yields since the aphids act as a significant sink, competing with the bolls, for energy. The late-season infestations (mid-Aug.to Sept.) are problematic because the aphids deposit honeydew on the exposed cotton lint, which reduces the lint value. Reasons for this change in pest status of cotton aphid are unclear; however, one of the most noticeable changes in cotton production over the last 10 years is the use of a plant growth regulator instead of irrigation and nitrogen deficits to limit early-season cotton vegetative growth. This has allowed cotton production practices in the SJV to evolve to higher nitrogen fertilization and irrigation inputs.
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The goals of our research are to examine the role that naturally-occurring predators play in controlling spider mites and determine if predatory mite releases can improve spider mite control. During 1996 & 1997, we performed large-scale releases of the western predatory mite using low release rates and found that releases did not increase predatory mite numbers and did not improve spider mite control. Thus,we have attempted to identify factors that could be limiting predatory mites in hope that we can improve spider mite biological control. During 1998 & 1999, we completed four experiments…
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The cotton stalk management study o f one-pass stalk embedding as a key component to a reduced tillage system and controlled traffic systems for cotton is in its fourth year of evaluation. The study was extended one extra year to verify yield results obtained in the 1998 crop year. The original hypothesis included reduced energy, improved soil condition, no disease differences, no nutrient differences and no yield differences. Of these hypothesis all are true except for yield differences. In years 1 and 2, no yield difference could be measured between stalk embedding and normal stalk disposal systems. However…
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Vern J. Elliott USDA-ARS
Shafter Research and Extension Center
17053 N. Shafter Ave. Shafter, CA 93263
(661) 746-8003
Fax (661) 746-1619
vjelliott@ucdavis.edu
Sticky cotton, the contamination o f cotton lint by insect honeydew, is a serious problem that makes it difficult for the textile industry to process the cotton fiber. This stickiness reduces the price paid to the grower and damages the quality reputation of entire production areas. Although insect management is playing the major role in reducing or preventing sticky cotton, remedial measures to reduce the stickiness of contaminated lint are still needed. Bioremediation, the use of microorganisms to degrade the contaminating sugars, may offer an economical and effective way to reduce the stickiness of lint.
Objectives of the current USDA ARS project are to examine the ability o f different strains o f yeast to utilize the sugars in insect honeydew, to select strains…
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