Post-harvest Diseases of Fruits & Vegetables

Protecting your harvest from disease does not end with harvesting. Your fruits and vegetables remain susceptible to disease even after they have been picked and stored. Although post-harvest fruits and vegetables are not susceptible to the same diseases as developing ones, post-harvest diseases can be equally detrimental to your fruits and vegetables and may even cause the complete loss of the harvest.


Penicillium, commonly referred to as blue mold, is a serious post-harvest disease that is especially harmful to apples. This fungal disease enters the harvested fruits and vegetables through cracks, bruises and wounds that are caused during the harvesting process. The infecting fungal spores cause light brown, watery spots at the point of infection. Progression of the infection causes the watery spots to spread and turn necrotic which causes rot. The rotted areas are pronounced by the presence of blue, fungal spores that cover the infected area. The disease moves quickly in warm conditions but continues a slow-growing process in cold storage. A few infected fruit can easily contaminate an entire harvest within a storage container. Penicillium infections are greatly reduced with careful harvesting practices. Harvesters should follow general sanitation practices and avoid injuring the fruit during harvest. Fungicidal treatments are also effective when combined with careful harvesting practices. Storage containers should also be disinfected prior to and after storage to eliminate cross contamination.

Sour Rot

Sour rot is a causal, post-harvest disease that is especially detrimental to citrus fruits. This fungal disease thrives in the soils around citrus trees and is transferred from the soil to the tree by wind and rain. Though this disease is generally present throughout the development of the fruit, sour rot only becomes an issue at or after the fruit has been harvested. This disease targets mature fruits that have been subjected to high moisture levels and high humidity. Similar to penicillium infections, the infected fruit first develops light, water-soaked areas. As the areas rot, the water-soaked areas develop into slimy, watery masses that are often accompanied by the presence of green mold. Along with chemical sanitizers, sour rot can be controlled by careful harvesting practices. The fruit should never come in contact with the tree’s surrounding soil, as the soil carries the infecting fungi. The fruit should be handled carefully to eliminate bruises and wounds. In addition, the fruit and storage containers should be carefully cleaned and the storage containers should be carefully monitored to prevent high temperatures and humidity levels.

Alternaria Rot

The alternaria rot disease will slowly decay your harvest of ripe fruits. This fungal disease is often seen on apples, tomatoes, kiwi and pears, as well as carrots, broccoli, potatoes and peppers. This disease develops on defoliated debris and infected vegetation that lie around your fruit and vegetable plants. The alternaria fungal spores are transported by wind and rain onto the fruit where they slowly germinate. One infected harvest pick can slowly contaminate an entire container of fruits or vegetables. Infected fruits and vegetables develop small, dark lesions that enlarge with the progression of the disease. The infected area rots into the interior of the fruits and vegetables, making the fruit a complete loss. There is no cure for alternaria rot. However, the disease can be controlled with proper sanitation of equipment, containers and other harvest supplies.

Keywords: post-harvest fruit diseases, post-harvest vegetable diseases, blue mold, sour rot

About this Author

Charmayne Smith is a business professional and freelance writer. She has worked in management for successful organizations since 1994. Smith draws on her business background to write articles, and her work has appeared in a variety of online outlets. She holds a degree in business from Cleveland State University.