Fungal Disease

Diseases

A plant disease caused by pathogenic fungi, which represent the largest and most diverse group of tree pathogens.

Fungal diseases are responsible for the majority of infectious tree diseases worldwide. Fungi reproduce through spores that can be dispersed by wind, water, insects, or human activity. Upon landing on a susceptible host under favorable conditions, spores germinate and penetrate plant tissues, colonizing internally and disrupting normal physiological functions.

Common fungal diseases of trees include Dutch elm disease, oak wilt, anthracnose, apple scab, powdery mildew, various root rots, and tar spot. Symptoms vary widely depending on the pathogen and affected tissue but may include leaf spots, wilting, cankers, dieback, fruiting bodies (mushrooms or conks) on wood, and root decay. Many fungal diseases are most active during warm, humid conditions.

Management of fungal diseases involves an integrated approach. Cultural practices include selecting resistant varieties, ensuring adequate spacing for air circulation, proper pruning to remove infected tissue, and avoiding overhead irrigation. Chemical treatments such as fungicide injections or sprays can be effective for many diseases when timed correctly. For some devastating diseases like Dutch elm disease, proactive trunk injection with fungicides like propiconazole can provide preventive protection for high-value trees.