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ARS Home » Pacific West Area » Salinas, California » Crop Improvement and Protection Research » Research » Publications at this Location » Publication #413595
Research Project: Disease Management and Improved Detection Systems for Control of Pathogens of Vegetables and Strawberries

Location: Crop Improvement and Protection Research

Title: Forecasting lettuce and spinach downy mildew airborne spore levels in California

Author
item Liu, Samuel
item CLARK, KELLEY - University Of California
item Anchieta, Amy
item AYALA, HANNAH - University Of California
item CORRELL, JAMES - University Of Arkansas
item PUTMAN, ALEXANDER - University Of California
item MONTAZAR, ALIASGHAR - University Of California Agriculture And Natural Resources (UCANR)
item Klosterman, Steven

Submitted to: American Phytopathological Society Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 5/14/2024
Publication Date: 7/27/2024
Citation: Liu, S.S., Clark, K.J., Anchieta, A.G., Ayala, H., Correll, J.C., Putman, A.I., Montazar, A., Klosterman, S.J. 2024. Forecasting lettuce and spinach downy mildew airborne spore levels in California. American Phytopathological Society Annual Meeting, July 27-30, 2024, Memphis, Tennessee.

Interpretive Summary:

Technical Abstract: California is the nation's leading producer of lettuce and spinach but faces significant challenges from downy mildew diseases caused by the obligate oomycete pathogens, Bremia lactucae and Peronospora effusa on lettuce and spinach, respectively. These diseases severely impact crop marketability. While disease-resistant crop varieties combined with calendar-based fungicide applications are used to manage these diseases, the repeated fungicide applications increase costs and can lead to the development of fungicide resistance. The aim of this work is to improve downy mildew management and reduce inputs and costs by exploring the relationship between airborne spore quantities and climate variability and developing predictive models to forecast spore levels. During the 2021-22 and 2022-23 growing seasons, spore counts were quantified in lettuce and spinach in several valleys of California, from the central coast to the southern desert. In particular, the work focused on key leafy greens production regions of the Salinas and Imperial Valleys with differing climates, and we analyzed correlations and linear regressions between spore counts and various climate variables. These analyses resulted in the development of preliminary models for forecasting airborne inoculum loads. Optimizing these models in future studies will enable growers to proactively time fungicide applications, which can reduce costs and enhance the sustainability of California's lettuce and spinach production.