INTRODUCTION
Bemisia whitefly populations are a significant annual threat to cotton production, particularly pima cotton, in the San Joaquin Valley. This pest has the potential to reduce cotton yields; however, the prospect of cotton lint contamination, creating a condition called sticky cotton, is the primary concern associated with whitefly infestations. Important research on sampling, damage potential, and management of Bemisia whiteflies has been conducted in Arizona. This research has formed the backbone of our present management scheme in California. In summary, this research supported three stages of whitefly management during the season with different insecticide chemistries during each stage. The need to management resistance and the characteristics…
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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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