August 2025 Edition

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Preventing Postharvest Disease Losses in Vegetable Crops

Vegetable produce is often soft, perishable, and particularly susceptible to a range of damage during harvest and storage. Growers can experience postharvest crop losses between 25% and 50%. A significant percentage of postharvest losses are caused by plant diseases. Infection by disease-causing pathogens can occur in the field and/or through wounds during harvest. Under moist conditions or high humidity, these infections can develop into molds, rots, or other decay. Even produce destined for fresh market can develop postharvest diseases during short-term storage.

Infection in the Field
Plant diseases such as fruit rots, leaf spots, and root rots can occur while plants are growing or while fruit are maturing (Figure 1). Infections can remain latent (dormant) until produce reaches a particular stage of maturity or until certain environmental conditions are reached. 

Management

• Maintain a disease management program all season.
• Discard diseased and damaged produce as soon as it is visible.
• Avoid mixing diseased produce with healthy produce (e.g., in storage bins).
• Apply fungicides at harvest or after harvest if field disease was present.

Infection During Harvest & Handling
Wounds, bruises, desiccation, and exposure to temperature extremes can weaken produce and allow pathogen entry, resulting in disease. Many of the same plant pathogens that infect crops in the field can also infect wounded or damaged produce during harvest. Disease may appear soon after produce is moved to the cooler or storage, or there may be a delay in disease development.

Management

• Minimize wounds and bruises during harvest, handling, and packaging.
• Raise bins and buckets off the ground during harvest.
• Cool produce as soon as possible.
• Avoid leaving harvested produce in the heat or sun.
• Wash dirty or muddy produce and dry thoroughly before storage.
• Wash and sanitize bins and equipment before each harvest.

Disease in Storage
Improper storage conditions can provide ideal environments for disease-causing organisms to infect (Figure 2). Healthy produce can become diseased in storage when moisture is too high, temperatures are too warm, and pathogens are present.

Management

• Separate produce by type, harvest date, and field origin.
• Cool produce as soon as possible while remaining within the safe range for the specific crop.
• Monitor storage temperature and humidity.
• Increase ventilation.
• Raise produce off the floor.
• Reduce surface wetness by maintaining equipment and keeping produce dry.
• Follow a strict sanitation program, which is critical.
  • If vegetables must be washed, they should be completely dry before storage. Keep all surfaces clean; sanitize regularly. Wash and sanitize all bins, tools, and harvest materials before bringing them into coolers or storage units.

  • Inspect stored produce regularly and discard damaged and diseased material immediately.

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Orchard Walk

When: Wednesday, August 13
Time: 6-8 PM ET
Where: University of Kentucky North Farm, 1925 Research Farm Road, Lexington

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