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Tree Fruit Diseases

Fully developed black knot.

An Introduction to Black Knot

Black knot is a fungal disease, caused by Apiosporina morbosa, that attacks stonefruit species in the genus Prunus. Black knot is known for irregular, thick, black swellings on limbs.

Black rot canker on diseased limb.

Black Rot Disease in Apples

Black rot disease, caused by the fungus Botryosphaeria obtusa, is concerning to homeowners with apple trees as part of their landscapes. 

Brown rot on maturing stone fruit (cherries).

Brown Rot in Stone Fruit

Brown rot (Monillinia fruticola) is a major disease of stone fruits. All stone fruit can be susceptible to this disease, with sweet cherries being the most susceptible. 

Cherry leaf spot lesions on leaf surface.

Cherry Leaf Spot

Cherry leaf spot is a fungal disease caused by Blumeriella jaapii (Rehm) Arx, formally known
as Coccomyces hiemali. It attacks the leaves, leaf stems, fruit and fruit stems.

Fire blight

Fire Blight on Pome Fruit

Fire blight damage can range from minimal to extremely severe depending on several factors.

Cracked apple from stress.

Fruit Cracking

Cultivar choice and tree care are the best ways to avoid and minimize cracking.

Reddish areas on developing leaves are a symptom of peach leaf curl. (Photo credit: MM Rahman)

Peach Leaf Curl

By applying fungicide in a timely manner, peach leaf curl can be controlled.