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Entomology and Plant Pathology, Oklahoma State University 127 Noble Research Center, Stillwater, OK74078 405.744.5527 Vol. 11, No. 19 http://entoplp.okstate.edu/Pddl/ Apr 13, 2012 Alfalfa Problems not Over Phil Mulder, Department Head and Extension Entomologist Although drought conditions have broken across the state, the status of alfalfa production is still under assault. We began the season with severe limitations in soil moisture, and extremely early weevil populations. Many growers elected to control these weevil populations early and hoped that alfalfa aphids would be simultaneously managed. Fortunately, rains arrived and alleviated much of the concerns about aphids; however, alfalfa weevil populations were the highest ever experienced. Many growers have made multiple applications for weevils this year and much of this was justified. Unfortunately, multiple applications can eliminate beneficial organisms (ladybird beetles, parasitic wasps, etc.). With the continued mild weather and weevils emerging early, we continue to see adult activity and may subsequently experience problems with more larval populations. The summer dormant period for weevil adults is cued in by temperature to some extent, but the primary driver is daylength in which the larvae matured. Since the daylength was still relatively short for much of the early populations, weevil adult activity may continue for a period of time followed by oviposition (egg laying) activity. The latter scenario remains to be seen, but could potentially occur. Growers with heavy adult alfalfa weevil populations are encouraged to manage these numbers. Now, how and when should they be managed? Unfortunately, we do not have well established thresholds for adult alfalfa weevil populations. Many growers have made the mistake of ignoring adult populations if the alfalfa is close to harvest and this may not be a bad decision if harvest is immediate; however, if harvest is delayed weevil adults will further continue defoliation and then begin feeding on stem epidermal tissue, further degrading the quality of an already depleted and compromised crop.
|Okla State Agency||
Oklahoma State University
|Okla Agency Code||'012'|
|Title||Pest e-alerts, 04/13/2012, v.11 no.19|
Oklahoma State University.
|Purpose||Alfalfa Problems not Over / Phil Mulder|
|For all issues click||Z2155.6 P713d|
|Digital Format||PDF Adobe Reader required|
|ODL electronic copy||Downloaded from agency website: http://entoplp.okstate.edu/pddl/2012/PA11-19.pdf|
|Rights and Permissions||This Oklahoma State Government publication is provided for educational purposes under US copyright law. Other usage requires permission of copyright holders.|