Diseases on Red Winesap Apple Trees

Fire Blight

• A bacterial disease, fire blight affects all members of the rose family, including apples. Although red Winesap exhibits some resistance to the disease, it is not immune. At petal fall, look for dead branches, discolored foliage and blossoms, and dried-up fruit. Cutting out all infected parts of the Winesap apple tree is your only course of action as there is no cure. Prevention measures include obtaining a soil test prior to applying fertilizer. This helps avoid the rapid vegetative growth that occurs when the Winesap is given excess nitrogen. Avoid injuring the tree during harvest.

Apple Rust

• Rust, a fungal disease caused by the pathogen Venturia inaequalis, is one of the most common and serious diseases of the Winesap apple. Cool, wet weather is conducive to its development. Symptoms include olive green splotches on the undersides of the tree’s foliage, leaf drop and deformed fruit. The fruit may also take on lesions that resemble black scabs. A good spray program controls the disease, including fungicides and a dormant spray in the winter. Prevent rust by keeping the soil around the tree free of fallen leaves, twigs and other debris.

Powdery Mildew

• Another fungal disease, caused by Podosphaera leucotricha, powdery mildew attacks in spring. Initial symptoms include distorted foliage and twigs that fail to develop to their full length. White fuzzy patches -- on the undersides of foliage located near the tips of branches – come next. Blossoms may dry up and the tree fails to produce fruit. Powdery mildew overwinters in buds and is most active during periods of high humidity, with temperatures between 66 and 72 degrees Fahrenheit. To prevent powdery mildew, increase air circulation around the Winesap by cutting down overhanging branches from nearby trees, removing other vegetation from within a 3-foot radius, and pruning the center of the tree to allow more air and sunlight to reach the branches. Contact the county cooperative extension agent to receive current fungicide recommendations in your region.

Apple Scab

• Apple scab is quite common on the Winesap apple and is easy to diagnose. Look for olive green lesions on the leaves and black, scab-like lesions on the fruit. Leaves may turn yellow and fall from the Winesap and the apples may appear distorted. Scab is most prevalent during wet weather. Fungicides containing captan or benomyl are effective against scab, and good orchard sanitation, including raking up fallen leaves and fruit, goes a long way toward preventing the disease.