- Fruits: berries (strawberries)
- Pest Management: cultural control, integrated pest management
Fusarium oxysporum f. sp. fragariae (FOF), causal agent of Fusarium wilt of strawberry, was first detected in California in 2006, in fields where pre-plant fumigation with methyl bromide and chloropicrin was no longer used. The disease is now found in all major strawberry production areas and methyl bromide, a key ingredient in fumigation mixtures, is expected to be unavailable by 2017. Only partial suppression of Fusarium wilt can be achieved by fumigation with chloropicrin alone. Some strawberry cultivars are resistant to Fusarium wilt, but most commonly grown cultivars are susceptible. Furthermore, preliminary studies indicate that the Fusarium wilt pathogen can colonize resistant strawberry plants and produce structures that survive in soil (=inoculum). Consequently, growing a resistant strawberry crop may contribute to increases in soil inoculum, which may eventually exceed levels resistant cultivars can tolerate. Therefore, there is an urgent need to identify rotation crops that will not support growth of the pathogen. To address this question, the biomass production of FOF on crops that are commonly grown in rotation with strawberries and on FOF resistant strawberry cultivars will be measured using culture dependent and independent methods. Many California strawberry growers rotate their fields with other crops and there is strong interest in understanding their relative potential to serve as hosts for FOF. However, barriers to adoption of crop rotation may still exist and need to be identified for producer adoption to occur. Therefore, an industry-wide survey will be conducted to investigate producer ability to rotate with specific crops. Concerns and perceived opportunities for specific crop rotations will then be addressed in extension materials. Results will be disseminated directly to growers, pest control advisors, and University of California Cooperative Extension (UCCE) professionals. This research will create and communicate a necessary tool for management of Fusarium wilt.
Project objectives from proposal:
1. Research: Identification of crops that do not serve as reproductive hosts for FOF: Identify the relative potential of common rotation crops (lettuce, spinach, broccoli, cilantro, raspberry, wheat) to serve as reproductive hosts of Fusarium oxysporum f sp. fragariae (FOF).
2. Research: Inoculum contribution by resistant strawberry cultivars: Identify the extent to which cultivars of strawberry (Fragaria x ananassa) that are resistant to FOF can serve as reproductive hosts of this pathogen.
3. Extension: Survey on Crop Rotation for Disease Suppression: Survey growers, pest control advisors, and other industry representatives to identify barriers to adoption of crop rotation as a disease management strategy for FOF. This survey will be conducted in the winter and spring of 2017
4. Extension: Dissemination of results: Results of our research on crop rotation will be disseminated through the following types of publications: peer-reviewed, social media, websites, California Agriculture Journal, and informational pamphlets. All University of California Cooperative Extension (UCCE) professionals and notable pest control advisors will be contacted and informed of research results and their application. Results will be presented at three industry meetings and a workshop.