Field studies in 2000 and 2001 evaluated the efficacy and longevity of an alternative strategy for control of corn earworm and European corn borer, key pests of sweet corn in Massachusetts. Corn oil and Bacillus thuringiensis subsp. kurstaki (Bt)were applied, alone or in combination, directly to the neck of the ear at a rate of 0.5 ml total material per ear. In one experiment, all treatments were applied on day 5 after silk initiation. Two first-instar corn earworm larvae were placed in the silk channel on days 3, 6, 9, 12, 15, or 18, and ears were evaluated 4 days later for feeding damage to kernels and larval mortality. Bt, oil and Bt + oil all increased corn earworm mortality and reduced kernel damage compared to untreated ears, but the combination of Bt + oil gave the best and most consistent protection, which lasted for 17 days following treatment. In a second experiment, the same treatments were applied daily from day 3 to 11 after silk initiation and all treatments were harvested at maturity. All treatments reduced damage and larvae compared to untreated controls. Earlier treatments were more effective against corn earworm, but timing of application showed no trend relative to European corn borer infestation. The proportion of the ear with undeveloped kernels decreased over time. These studies suggest that treatments on day 5 or 6 after silk initiation with a combination of corn oil and Bt provide a high level of marketable ears.
Species 1: Lepidoptera Noctuidae Helicoverpa zea (corn earworm, tomato fruitworm)
Species 2: Lepidoptera Pyralidae Ostrinia nubilalis (European corn borer)
Keywords: Bacillus thuringiensis, sweet corn
Back to Display Presentations, Subsection Ce. Insect Pathology and Microbial Control
Back to Posters
Back to The 2002 ESA Annual Meeting and Exhibition