Botrytis blight, rot and gray mold caused by Botrytis spp. are the most recurrent disease on both ornamental and vegetable transplant greenhouse crops in California, generating losses in these industries. Our research group (Del Castillo Lab) have recovered Botrytis from a wide host range of ornamentals including rose, geranium, lavender, vinca, Monterey pine and giant sequoia seedlings, among other hosts.  For vegetable transplants, it was the most prevalent disease (61%), infecting processing tomato, lettuce, broccoli, and cabbage seedlings.  

To manage these diseases, growers mainly rely on fungicide applications.  However, disease losses due to this pathogen are still prevalent, suggesting development of pathogen fungicide resistant populations.  In this project, we will evaluate if Botrytis population from greenhouse and nursery production are resistant to one or multiple fungicides commonly applied.  We aim to characterize Botrytis populations from greenhouse grown crops in California, by determining their fungicide resistance profile, and evaluate if host or location have a correlation with fungicide resistance.  The findings from this project will be valuable for producers as, as we will identify which fungicides are no longer effective for Botrytis management. 

As part of this project, we will be sampling at greenhouse and nurseries across the state during winter and spring (2024-2025).  If you are interested in participating in this project, by allowing us to sample in your facility, and get information regarding fungicide resistance profiles from Botrytis in your location, contact jdelcastillo@ucdavis.edu. 

This project will be carried with funds from the CADPR, the Western IPM, and the USDA-NIFA Crop Protection and Pest Management programs. We will provide project updates through the UCNFA and other extension events during 2025 and 2026.