Harvesting and Storage: Preventing Postharvest Diseases on Tomato

Scientific concepts / nature phenomena presented

• Postharvest diseases in tomatoes and their impact on yield loss (reported as ~25–50% of losses occurring at/after harvest).
• Disease entry and infection timing
  • Field infections can be latent (present without visible symptoms) and later develop during storage.
  • Harvest/handling–induced infections occur when pathogens enter via wounds and bruises created by physical damage, sunscald, desiccation, or heat.
  • Storage diseases develop when pathogens are present and conditions support growth.
• Pathogen types and requirements
  • Fungi and bacteria can colonize damaged/overripe tissue and multiply, with symptoms appearing days to weeks later.
  • Pathogens generally require wet conditions and moderate temperatures; high humidity and wet surfaces in coolers favor disease.
  • Contaminated bins/crates/surfaces and contaminated produce act as inoculum (source of pathogens).
• Latent infections
  • Infections may not be visible at harvest but later cause rots and molds in coolers or packed boxes.

Specific diseases mentioned (tomato/produce)

• Botrytis (gray mold)
• Bacterial soft rot
• Fusarium fruit rot

Preventative management approach (methodology / plan)

Season-long field disease management

• Use a combination of cultural practices and fungicides, starting early and continuing through harvest.
• Remove damaged/diseased produce from fields as soon as symptoms appear to limit spread.

Harvest practices

• Use clean pick: pick all ripe fruit and separate marketable vs. non-marketable produce.
• Never leave produce in the field or on the ground.
• Minimize harvest and handling damage
  • Avoid wounds, bruising, heat, and sun exposure.
  • Cool produce as soon as possible (even shade can be too hot and can cause desiccation).
  • Raise bins off the ground to prevent soil/debris contact.
• Sanitize containers
  • Sanitize bins and boxes before and after harvest to reduce crosscontamination.

Storage environmental control

• Keep produce cool and dry.
• Set cooler temperature as low as possible for the specific produce type.
• Maintain humidity appropriate for that produce.
• Maintain ventilation by proper spacing/organization.
• Reduce condensation/wet surfaces (avoid conditions that raise moisture).

Sanitation and lot management

• Keep coolers and equipment surfaces clean and sanitized.
• Remove contaminated produce often.
• Separate bins/boxes by crop type, date, and field to enable removal of affected lots quickly.

Training and monitoring

• Train employees to recognize diseases and to prevent damage and crosscontamination during harvest/packing.
• Know the most common diseases both in the crop and in storage.

Researchers / sources featured

• University of Kentucky, Department of Plant Pathology (referenced as an additional resources source).