Optimizing onion thrips management programs in organic onion production

Onion thrips, Thrips tabaci Lindeman, is a major onion pest causing severe foliar damage. Feeding injuries of onion thrips reduce photosynthesis, which leads to smaller bulb sizes. Onion thrips management in organic onion production has limited available tools and mainly relies on insecticide applications. Several insecticides have been evaluated for thrips management in organic production, and effective chemicals have been determined. With Spinosad being the most effective insecticide for thrips management, studies were conducted to optimize the use of Spinosad to provide sufficient management as well as to preserve the effectiveness of Spinosad by reducing the chance of resistance development. Programs with sequences of insecticide applications involving other available insecticides have been developed based on thrips pressure. Along with the use of a resistant cultivar and reflective mulch, a range of action thresholds were compared to determine the baseline for thrips management in organic onion production, which would avoid yield reduction without excessive applications.