Avocado Fruit Drop: Causes and Management in Coastal California

Primary Causes of Premature Fruit Drop

• Environmental stress: Cold snaps, drying winds (Santa Anas)
• Water stress: Both drought and waterlogging
• Natural thinning: Tree aborts excess fruit it cannot support
• Pollination issues: Incomplete fertilization

Your Situation: San Rafael, CA

Recent windy period likely caused physical stress and accelerated water loss. Avocados are sensitive to wind—stomata close, photosynthesis stops, fruit aborts.

Management Strategies

• Windbreaks: Plant or construct on windward side
• Irrigation: Deep, consistent watering during dry/windy spells
• Mulch: 4-6 inches to moderate soil moisture/temperature
• Nutrition: Balanced avocado/citrus fertilizer per schedule
• Acceptance: Some drop is natural; tree regulates crop load

Local Expert Resource

UC Marin County Extension: Steven Swain, (415) 499-4204, svswain@ucdavis.edu. They offer avocado-specific guidance for coastal conditions.

Long-Term Perspective

Young trees (under 5 years) often drop most fruit. Production stabilizes with maturity. Focus on tree health—fruit follows.