Apple Trees Fungus or Disease Treatment

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Apples on a healthy tree

Most of the diseases of apple trees are associated with fungus. They can be controlled by fungicides or other physical measures. Appropriate care and attention to the appearance of the apple tree can help keep it in good health and its harvest plentiful. To properly use a fungicide, ask your local garden center specialists for assistance. They can direct you on how to use the best products for your area of the country.


Apple Scab

Apple scab is caused by a fungus that appears in the latter part of autumn or in early spring. It looks like black or brown bubbles on the leaves, and if it is not treated the apples will have black or brown bumps.

The wind spreads apple scab. This disease can spread quickly if left untreated for any length of time. Leaves fall off the tree prematurely when it is infected with apple scab. The apples mature unevenly. Eventually the apples crack and spoil.


To treat apple scab, prune the affected areas and burn the material that is cut off the tree. Do not store any infected apples. There is no permanent damage to the apple tree from apple scab disease.

Powdery Mildew

Powdery mildew is a fungal disease of apple trees. It looks like powder on the leaves and bark of the apple tree. You can see powdery mildew during times of high humidity, and it also grows well during hot, dry weather. If left untreated, powdery mildew causes major weakening of the apple tree. The new growth is affected first. This weakens the tree, but a healthy tree can survive powdery mildew without too much damage.


Treat powdery mildew with a strong fungicide or sulfur spray. Also make sure there is good air circulation between the branches.

Fire Blight

In apple trees, fire blight gives foliage a scored appearance. The young shoots of the apple tree that are infected will wither and die and so will the apple blossoms. As with apple scab, cut back any infected branches and burn all that is removed from the apple tree.


Black Rot

Black rot is a fungus appearing on the apples when they are ready to harvest. It occurs where the apples have had physical damage. The disease starts out as small brown spots on the apple, which then get bigger as the apple grows. The spots turn brown and then turn black. Black rot will also attack the bark and twigs and may survive over the winter. If you catch black rot early, the fruit is treated with sulfur spray. Make sure to prune any infected wood. Destroy it and then use a fungicide to prevent further damage to the apple tree.