Evaluating Organic and Biofungicides for Powdery Mildew Management in Field-Grown Tomato
ISSN 2158-9429
Volume 18, Issue 2 - December 2025
Editor: Bindu Poudel-Ward
Abstract
Powdery mildew, caused by Leveillula taurica, is a widespread disease affecting tomato production in California, particularly in organic and low-input systems. A field trial was conducted in Hemet, CA, to evaluate the efficacy of organic and experimental fungicide treatments in managing powdery mildew on tomato (Solanum lycopersicum L., cv. Moneymaker). Treatments included PREV-AM®, various rates of 009EPA, and several organic biofungicide (THYMIC®, CINNACTION®, and Milagrum Plus®) combinations with OROBOOST® adjuvant. Applications were made at 7–10-day intervals beginning in early September 2024. Disease severity, yield, and sunburn damage were assessed. Results showed that PREV-AM® significantly reduced powdery mildew severity compared to untreated controls, with higher rates of 009EPA and combination treatments also providing moderate to good control. However, no significant differences in marketable yield or sunburn losses were observed among treatments. These findings suggest that several organic and biofungicides can effectively reduce powdery mildew symptoms but may not directly translate to increased yields under moderate disease pressure. Integration of these materials into broader disease management strategies is recommended for sustainable tomato production systems.
Abbreviations:
UCANR = University of California Agriculture and Natural Resources;
IPM = Integrated Pest Management;
ANOVA = Analysis of Variance;
CIMIS = California Irrigation Management Information System
Keywords:
powdery mildew, tomato, Leveillula taurica, organic fungicide, biofungicide, biopesticide, small farms, PREV-AM®, OROBOOST®, disease management, field trial, sustainable agriculture
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