Late Season Aphid Management

Since the introduction of winter canola into Oklahoma, producers have battled devastating aphid infestations. During the initial years of production it became clear that canola could not be successfully grown in Oklahoma Without an effective aphid management plan. Turnip aphids can have the greatest impact killing young plants from November-March if untreated. Green-peach aphids occur throughout the growing season at high numbers. Whereas cabbage aphids are frequent late-season pests during flowering and seed-pod development. In response to an initial crisis caused primarily by turnip aphids, the OKANOLA team documented the effectiveness and profitability associated with Nicotinoid seed treatments, and developed sanmpling protocols and economic thresholds for this pest during the early spring. Significant late spring infestations of Green-Peach and Cabbage aphids (thousands/plant) continue to be a major concern for producers of producers sprayed insecticides for aphids at least once during spring 2010. However, economic thresholds for late eason infestations have not been established and information on the protitability of late season suppression is currently not available. According to the US Canola Association the impact aphid populations on Winter and spring canola needs to be evaluated in greater detail, and parasites and predators need further study. We plan to evaluate the impact of late season aphid infestations on canola yield and oil content in seeds, and document the profitability of late­season curative insecticide treatments.

During the late spring of 2010 75% of canola growers sprayed their Íields with insecticides to suppress aphids. These applications may be justifiable. However, there is no data available for Oklahoma producers as to whether yields were protected enough to justify the expense of an application. Justifiable use of insecticides will increase profit margins of producers both short and long-term, and any reductions in use will delay insecticide resistance While conserving natural enemies. Interestingly, during the spring of 2010 a few Íields that were not sprayed had large numbers of natural enemies, which may have contributed to aphid reductions. Proven profitable approaches for late season aphid suppression are essential for the completion of an aphid management plan.

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