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Influence of Grower Agronomic Practices on Cotton Aphid Populations in California Cotton

L. D. Godfrey, K. E. Keillor and R. B. Hutmacher


 
ABSTRACT

The cotton aphid (Aphis gossypii Glover) escalated from an occasional pest to an annual pest of San Joaquin Valley (SJV) cotton during the 1990's. Although the cotton aphid is not a new insect in the SJV, the change in the bionomics of this pest dictated that new research efforts be directed toward the biology, damage thresholds, and management. Following the severe outbreak in 1997, populations and management appear to have stabilized. As a means to reduce inputs, the influence of cultural control measures on cotton aphid populations have been evaluated. Nitrogen application rate has been of particular interest. Aphid levels were monitored in seven large plot grower field studies with four differential nitrogen regimes (50 to 200 lbs./A nitrogen) during both 1999 and 2000. There was consistently a trend for more aphids in the 200 lbs./A nitrogen treatment compared with the lower treatments. In addition, the interaction between nitrogen level and pyrethroid application (a common production practice used to manage lygus bug populations) was examined. At the onset of aphid build-up, application of either a pyrethroid insecticide (Capture®) or a chloronicotinyl insecticide (Provado®) or no insecticide was superimposed. With the high nitrogen treatments (150 and 200 lbs. N/A), there were 3 to 6 times more aphids in the Capture plots compared with the untreated. The flaring effect was mitigated in the low nitrogen treatments.





Reprinted from Proceedings of the 2001 Beltwide Cotton Conferences pp. 964 - 967
©National Cotton Council, Memphis TN

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Document last modified XXXXXX, XXX XX 2001