Mold of Fruit Trees

Overview

Common molds of fruit trees are easy to identify based on their color-specific names. Green mold and blue mold form from different strains of Penicillium fungi. These molds affect fruit even after they have been picked from the tree, so extra control precautions are important. Familiarize yourself with symptoms and significant management methods.

Host Plants

Green mold attacks citrus trees in all regions, according to the University of Florida IFAS Extension. Blue mold thrives on apple and pear trees, according to the Penn State University Department of Plant Pathology. Both types of fruit mold develop on tree fruit via sporadic airborne spreading.

Fungal Infection

Green mold is caused by the fungus Penicillium digitatum. The fungi inhabit soil and infect fruit whether it is still on the branch or has fallen to the ground. Injured citrus fruit is more vulnerable to infection than healthy fruit, according to the University of Florida IFAS Extension. Blue mold is caused by the fungus Penicillium expansum and is also referred to as Penicillium rot or soft rot. These pathogens attack fruit that is picked before reaching full maturity as well as overly mature or wounded fruit, according to the Penn State University Department of Plant Pathology.

Symptoms and Damage

Green mold symptoms are often confused with blue mold in the beginning stages. Affected areas appear saturated with water and soft. White mold forms over this dead tissue and then smaller green spore spots form in the center of these 1-inch, round lesions, according to the University of Florida IFAS Extension. The green spores quickly cover the entire fruit, rendering it unsafe for consumption. Blue mold causes similar water-like soft spots that emit an unpleasant scent. In moist conditions, blue-gray spores develop all over the fruit and it thoroughly rots, according to the Penn State University Department of Plant Pathology.

Considerations

Fungal mold spores can thrive nearly anywhere. As fruit is harvested and stored, any tools, storage equipment or packing equipment that makes contact with the tree fruit becomes contaminated. Spores also survive in water, according to the Penn State University Department of Plant Pathology. Take measures to clean and fully sanitize every location and surface with which fruits come into contact to prevent spread of disease. Additionally, harvest fruit at the appropriate time and avoid causing injury to prevent infection.

Chemical Control

Blue mold has become resistant to fungicides containing the active ingredient benzimidazole, deeming it nearly worthless as a pre-harvest treatment. For this mold problem, apply calcium treatments after harvest to increase mold resistance, according to the Penn State University Department of Plant Pathology. For green mold control on fruit trees, fungicides containing imazalil are effective and will treat benzimidazole-resistant mold, according to the University of Florida IFAS Extension.

Keywords: fruit tree mold, blue mold fruit, green mold fruit

About this Author

Tarah Damask's writing career, beginning in 2003, includes experience as a fashion writer/editor for Neiman Marcus, short fiction publications in "North Texas Review," a self-published novel, band biographies, charter school curriculum, and articles for eHow. She has a love for words and is an avid observer. Damask holds a Master of Arts in English and creative writing from the University of North Texas.