Alternative IPM Programs for Management of Lepidopterous Larvae in Fall Lettuce
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AbstractFor a third year, a large block experiment was conducted at the Yuma Ag Center to compare the field performance of several lettuce IPM programs for control of lepidopterous larvae. Conventional, Reduced -risk , Bio-based and Modified IPM spray regimes were applied to control beet armyworm, cabbage looper and Heliothis species throughout the fall growing season. Differences in populations of total larvae among the treatments, relative to insecticide treatments and timing of application were observed at various times during the season. In general, the Conventional, Reduced -risk and Modified IPM approaches provided the most consistent control of lepidopterous larvae following each application. Harvest data showed that the spray regimes had a significant influence of head lettuce yield or quality. Maturity and quality were significantly reduced in the untreated control. An economic analysis shows that net returns varied widely among the management programs at different market prices. In conclusion, this study provides a strong data base to support the need for the development of experimental and biorational insecticide products as alternatives to conventional management programs in desert lettuce production. In addition, it demonstrates the dependance of IPM programs on a broad range of plant protection chemicals and control tactics.