If so there’s a few key things you should know when planning to plant crabapples trees or are maintaining them in your landscape.
-Crabapple scab is a highly common fungus that annually attacks the new leaves and flowers. The occurs during the wet spring whether, about the same time as bud break. Fungus spores are shot out of fruiting structures that have over wintered in fallen leaves and rotted fruit. Symptoms will begin to develop with in three weeks of being infected. It will appear as an olive colored velvety growth on lye leave surface. Leaves begin to turn yellow and fall off prematurely and fruit has rough spots. This is poor for the over all health of the tree.
– Spray you Crabapples
You can spray you crabapples with fungicide. How ever most tree company’s offer 2 sprays one at bud break an a second ten day later which can be some what effective if the spring whether is not very wet. In the apple orchard industry trees are sprayed at bud break then in ten day intervals or every day after it rains. Which could a lot of sprays!
– Cultural Practices
Raking the leaves and fruit from under the tree, and taking them away will greatly reduce the over winter fungus. There are disease resistant varities of crabapples such as Brandywine White angle.