Location: Horticultural Crops Disease and Pest Management Research Unit
Project Number: 2072-22000-045-068-A
Project Type: Cooperative Agreement
Start Date: Sep 1, 2026
End Date: Dec 31, 2027
Objective:
The proposed project will develop and validate pomace-derived antifungal extracts as practical, cost-effective tools for integrated Botrytis management, using strawberries as a model crop and integrating the approach into existing spray programs.
The specific objective is:
1. Screen and characterize antifungal efficacy of plant-based extracts against Botrytis cinerea using in vitro assays and detached strawberry leaf experiments.
Approach:
Activity 1: Extract preparation and characterization. Pomaces from grapes, citrus, and olives will be tested based on prior evidence of antifungal activity of these materials. Pomace will be collected through wine/juice processing in lab or local processors, dried in an oven at 40 °C for 48 h and stored in a refrigerator until use. Established scalable, cost-effective aqueous or ethanol-based extraction methods will be used. Dried pomace will be ground into powder, mixed with solvent, and subjected to ultrasound-assisted extraction to improve efficiency. Following extraction, solids will be removed by filtration and centrifugation; ethanol will be removed by rotary evaporation when applicable. Extract yield will be quantified using total phenolic content (TPC) measured by the Folin–Ciocalteu assay, and extracts will be normalized based on TPC to minimize variability among pomace sources.
Activity 2: Antifungal efficacy evaluation in growth media. Antifungal activity of each extract against Botrytis cinerea will be evaluated using two complementary assays: 1) spore germination assay to determine spore inactivation, and 2) mycelium growth assay to determine fungal growth inhibition. For spore germination assay, Botrytis spores will be spread onto potato dextrose agar (PDA) plates supplemented with selected extract concentrations and incubated at 25 °C for 10-12 h, with or without light (performance enhancer), and measured for germination rate. For mycelial growth inhibition, fungal growth curves will be monitored over 72 h in microtiter plates using spectrophotometry to determine the minimum effective concentration required for growth suppression. Treatments with extract alone, light alone, and extract-plus-light will be compared to untreated controls to assess synergistic effects. Data will be analyzed using analysis of variance (ANOVA) to compare treatments, and extracts showing significant spore inactivation and growth inhibition are considered effective.
Activity 3: Antifungal efficacy on detached leaves and harvested fruits. Selected extracts will be assessed on detached strawberry leaves and harvested fruits to assess disease incidence and severity under biologically relevant conditions. Leaves and fruits will be inoculated with Botrytis spores, sprayed with optimized extracts concentrations from Activity 2, and incubated with or without light exposure. The leaf and fruit samples will be measured for infection occurrence and lesions size over 1 to 4 weeks. Data will be analyzed using Fisher’s exact test and logistic regression to determine significance in efficacy. The extract demonstrating the most consistent and effective disease suppression will be selected for formulation and greenhouse evaluation.