Location: Emerging Pests and Pathogens Research
Project Number: 8062-22000-023-023-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Jul 1, 2024
End Date: Jun 30, 2025
Objective:
1. Collect isolates of C. coccodes and V. dahliae from commercial potato crops in the Pacific Northwest, the Upper Midwest, and the Northeast. (Cooperator and ARS PI)
2. Determine proportion C. coccodes and V. dahliae recovered from plants expressing early dying symptoms. (Cooperator)
3. Perform greenhouse or growth chamber experiments to determine if co-infections of C. coccodes and V. dahliae synergistically impact disease severity compared to single infections. (ARS PI)
Approach:
Objective 1. Stem samples will be collected from potato plants showing early dying symptoms. Samples will be collected from the Pacific Northwest, the Upper Midwest, and the Northeast during the 2024 growing season to represent the breadth of potato production environments in the United States. Three to five fields will be sampled in each region, and samples will be collected four to six times throughout the season. During each sampling, one stem from each of ten plants will be collected at ten sites per field. Isolates of V. dahliae and/or C. coccodes will be recovered from the symptomatic tissues using semi-selective media and standard techniques.
Objective 2. Quantitative PCR will be used to quantify the amount of V. dahliae and C. coccodes in each sample. A multiplex qPCR assay for the quantification of V. dahliae and C. coccodes in potato stem tissue developed and validated by Dr. Pasche’s program will be used.
Objective 3. Co-infection experiments will be conducted in a growth chamber or greenhouse experiment to determine if co-infections of V. dahliae and C. coccodes synergistically impact disease development. Representative isolates of each pathogen will be selected for the study. The study will include eight treatments: (1) V. dahliae root inoculation; (2) C. coccodes root inoculation; (3) C. coccodes stem inoculation; (4) C. coccodes foliar inoculation; (5) V. dahliae root inoculation plus C. coccodes root inoculation; (6) V. dahliae root inoculation plus C. coccodes stem inoculation; (7) V. dahliae root inoculation plus C. coccodes foliar inoculation; (8) non-inoculated control. Each treatment will be replicated four times and the experiment will be done twice.
