This is Why the Leaves Are Curling on Your Apple Tree
My apple tree has curling leaves on it. Is this a fungus? What can I do about it?
Are the leaves on your apple tree curling and dropping? There could be several reasons for this, whether it be a pest or mold problem. Find out what is making your apple tree's leaves curl and how to prevent it to get the juiciest, freshest apples ever.
Powdery mildew fungus could possibly cause the leaves of your apple tree to curl or be distorted, but you also would see a powdery film or residue on the leaves if this is the case. To stop powdery mildew growth, pluck off leaves that show sign of infection as soon as you see them. Give your tree air to breathe by pruning regularly.
Various insects can cause leaves to curl on apples. Aphids and leafrollers are the 2 most likely candidates. Look closely inside the rolled or curled leaf for evidence of the insects; spray a nontoxic insecticide if the condition is severe. If the amount of leaf rolling is minor, the tree should continue to produce a good crop without the need for a spray.
Apple scab is another condition known to take over apple and crabapple trees. Humid, rainy, and hot weather promotes the growth of fungus. Apple scab first appears as a velvety green spot and turns leaves yellow before they drop. Unfortunately, the disease is hard to control for most regions that experience rain and summers. The most effective way to prevent apple scab is to avoid it altogether by planting resistant varieties.