Evaluation of organic strategies to control a new invasive pest, swede midge, Contarinia nasturtii (Diptera: Cecidomyiidae)

• 2011 annual report
• 2012 annual report

Swede midge, Contarinia nasturtii, (Diptera: Cecidomyiidae) is a newly invasive insect pest that can cause devastating losses (>90%) to some Brassica crops. Swede midge larval feeding causes swelling or distortion of the tissues, and prevents head formation in broccoli and cauliflower, resulting in unmarketable produce. After establishing itself in Ontario, Canada in 2000, the midge is now expanding eastward into the Northeastern States. Due to its recent invasion, pest management recommendations tailored for organic and small scale vegetable growers do not currently exist. Concern about swede midge coming from organic vegetable growers was the impetus for this proposal. Current recommendations include long and widely spaced crop rotations, use of foliar and systemic conventional pesticides, and frequent insecticide applications to prevent midge damage. Currently, there have been pest control options that are compatible with organic agriculture that have been examined in the lab, but not yet in the field. In this study, we propose to examine: (1) the use of row covers for early season midge control, (2) the efficacy and dosage of several OMRI-certified insecticides in controlling swede midge late in the season, and (3) examine the use of entomopathogenic nematodes and Bt var. israelensis as a soil drench to control the midge in the soil. Our target audience will be organic and small-scale vegetable growers in the Northeastern US. Because the midge damage symptoms are difficult to detect, we will hold on-farm instructional workshops to demonstrate to growers how to detect the midge and how to manage midge populations. ?