Evaluation of Integrated Bacterial Disease Management Options for Organic Onion Production in Southeastern and North Central United States
Project Director
Bhabesh Dutta
Year Funded
2019
Award Number
2019-51106-30191
Funded Institution
University of Georgia
Grant Program
ORG (Organic Transitions)
USDA NIFA Report
Project Overview
Center rot, caused by the seedborne bacterial pathogens Pantoea spp., is a leading cause of pre- and post-harvest crop loss in organic onions. Copper can protect the crop but feeding damage by onion thrips facilitates pathogen entry and renders copper ineffective. This project aimed to develop an organic IPM strategy against the thrips-Pantoea complex including physical, cultural, biological, and NOP-allowed substance-based controls. Trials were conducted in Georgia and Michigan to develop integrated strategies for two major onion production regions.
Farmer Takeaways
(1) Alternating copper with biocontrol agents (Bacillus subtilis and B. mycoides) to manage center rot reduces the frequency of copper needed from every five days to every 15 days.
(2) However, tank mixing copper with the biocontrol reduces efficacy.
(3) Multiple bacterial and fungal diseases affect onion. The disease complex varies with location and evolves from year to year; thus, correct diagnosis is important.
(4) Weeds, thrips, and pathogens interact to promote onion diseases; thus, organic IPM must address all three.
Project Outputs
Bacterial Diseases of Onions in Georgia – Factsheet | University of Georgia
Koirala, S., Shin, G.Y., Kvitko, B., and Dutta, B. 2024. Integrating biocontrol agents with copper for center rot management in onion. Crop Protection 184.
Constancio, N., Higgins, D., Hausbeck, M., and Szendrei, Z. 2022. Onion thrips (Thysanoptera: Thripidae) host plant preference and performance are mediated by a facultative plant pathogen of onion. Environmental Entomology 51(6): 1158-1165.
Stumpf, S., Leach, L., Srinivasan, R., Coolong, T., Gitaitis, R., and Dutta, B. 2021. Foliar chemical protection against Pantoea ananatis in onion is negated by thrips feeding. Phytopathology 111: 258-267.
Zhao, M., Kvitko, B.H., Gitaitis, R.D., and Dutta, B. 2021. Bacterial streak and bulb rot of onion. Plant Health Instructor 21.
Koirala, S., Zhao, M., Agarwal, G., Stice, S., Gitaitis, R.., Kvitko, B., and Dutta, B. 2021. Identification of two novel pathovars of Pantoea stewartii subsp. indologenes affecting Allium sp. and millets. Phytopathology.