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ARS Home » Midwest Area » Madison, Wisconsin » Vegetable Crops Research » Research » Publications at this Location » Publication #380457
Research Project: Trait Discovery, Genetics, and Enhancement of Allium, Cucumis, and Daucus Germplasm

Location: Vegetable Crops Research

Title: Potential for managing onion thrips (Thrips tabaci) in organic onion production using multiple IPM tactics

Author
item IGLESIAS, LINDSY - Cornell University
item Havey, Michael
item NAULT, BRIAN - Cornell University

Submitted to: Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/13/2021
Publication Date: 3/1/2021
Citation: Iglesias, L., Havey, M.J., Nault, B.A. 2021. Potential for managing onion thrips (Thrips tabaci) in organic onion production using multiple IPM tactics. Insects. 12(3). Article 207. https://doi.org/10.3390/insects12030207.
DOI: https://doi.org/10.3390/insects12030207

Interpretive Summary: Onion thrips is a major pest in organic onion production and effective integrated pest management strategies are lacking. Our objective was to evaluate combinations of onion cultivars with semi-glossy foliage associated with less feeding damage and reflective mulch, with or without bioinsecticides (spinosad + neem oil), to manage onion thrips in organic onion production. Thrips densities were assessed weekly and bulbs graded and weighed at harvest. Onions sprayed with spinosad + neem oil had fewer onion thrips (adults: 74% (2019); larvae: 40% (2018), 84% (2019) and produced higher yields (13% (2018), 23% (2019)) than onions that were unsprayed, regardless of mulch type or cultivar. ‘Rossa di Milano’ had relatively consistent reductions in both adult and larval thrips populations compared with ‘Bradley’ (21% (2018), 32% (2019)) and B5336AxB5351C. However, ‘Rossa di Milano’ had the lowest marketable yield in both years. Reflective mulch reduced densities on certain dates in both years compared to white mulch, but the largest and most consistent reduction only occurred in 2019. Reflective mulch had no impact on bulb yield. While spinosad + neem oil was highly effective, none of the treatment combinations showed significant and consistent benefits. Future thrips management in organic onions will require bioinsecticides. This research will be of interest to growers of organic onions in order to reduce losses due to thrips feeding.

Technical Abstract: Onion thrips (Thrips tabaci Lindeman) is a major pest in organic onion production and effective integrated pest management strategies are lacking. Our objective was to evaluate combinations of semi-glossy onion cultivars that suffer less feeding damage (e.g., ‘Rossa di Milano’ and B5336AxB5351C) and reflective mulch, with or without bioinsecticides (spinosad + neem oil), to manage T. tabaci in organic onion production. Thrips densities were assessed weekly and bulbs graded and weighed at harvest. Onions sprayed with spinosad + neem oil had fewer T. tabaci (adults: 74% (2019); larvae: 40% (2018), 84% (2019) and produced higher yields (13% (2018), 23% (2019)) than onions that were unsprayed, regardless of mulch type or onion cultivar. ‘Rossa di Milano’ had relatively consistent reductions in both adult and larval thrips populations compared with ‘Bradley’ (21% (2018), 32% (2019))and B5336AxB5351C. However, ‘Rossa di Milano’ had the lowest marketable yield in both years. Reflective mulch reduced densities on certain dates in both years compared to white mulch, but the largest and most consistent reduction only occurred in 2019. Reflective mulch had no impact on bulb yield. While spinosad + neem oil was highly effective, none of the treatment combinations showed significant and consistent benefits. Future T. tabaci management in organic onions will require bioinsecticides.