Development of a USDA NIFA SCRI proposal to combat onion bacterial diseases across the US
CSANR Project 174
Bacterial diseases have increased the risk of growing onions in the US. Efforts to limit losses to bacterial rot in fields, storage, and shipping have had very limited success. “Stop the rot: Combating onion bacterial diseases with pathogenomic tools and enhanced management strategies” will advance scientific understanding of onion bacterial diseases substantially and provide the industry with more effective mitigation tools. The project integrates research and extension efforts addressing the three components of the disease triangle: pathogen, host, and environment; and accounts for farm- and industry-level economic assessments. Objective 1: Utilize comparative genomics to identify virulence factors of different onion bacterial pathogens to develop diagnostic tools and phenotypic resistance screening methods for onion bacterial diseases. Activities include annual surveys of onion crops in six US regions, and assembly of a national library of bacterial pathogen strains to facilitate searching for diagnostic targets and virulence determinants. Hypotheses underlying Objective 1 include: 1a. Rapid, robust, and regionally-specific detection assays for bacterial pathogens are crucial for mitigation strategies; 1b. Comparative bacterial genomics will identify virulence factors to develop practical diagnostic tools for onion bulb rot pathogens; 1c. Phenotypic resistance screening methods will speed the breeding of disease resistant onion cultivars; 1d. Economic assessment of bacterial disease impacts on US onion production will clarify opportunities to enhance profitability. Objective 2: Identify production practices, environmental factors, and inoculum sources that determine bacterial disease outbreaks in order to develop environmentally and economically viable management programs. Activities include coordinated field trials in six US onion production regions to evaluate locally relevant irrigation, fertility and cultural practices and pesticide programs for the impacts on bacterial diseases, and to explore economic implications of each. Hypotheses underlying Objective 2 are: 2a. Epidemiological studies will reveal how production practices, environmental factors, and inoculum sources impact bacterial diseases; 2b. Combined with knowledge generated by Objective 1, enhanced strategies to reduce bulb rots will be identified; 2c. Adoption of data-driven recommendations by onion producers/packers will limit economic losses from bulb rots; 2d. Economic and stakeholder assessments of enhanced management strategies will improve onion production efficiency and productivity.
Lindsey du Toit