Hello,

First of all, my response is based on what you stated in your question (without any images to look at)—you really needed to spray as a preventive before the leaves started to fall. The leaves will return and likely have apple scab unless you do another preventive spray.

It sounds like your crabapple tree is showing symptoms of apple scab, a common fungal disease caused by Venturia inaequalis. The yellowing and wilting of leaves with brown edges are typical signs. Pruning and mulching are good cultural practices, but if done improperly, they can sometimes contribute to stress on the tree, which may exacerbate the issue.

Here is information on apple scab and other crabapple diseases:

Apple scab - Integrated Pest Management (msu.edu)

Crabapple Diseases (psu.edu)

Here are some management tips based on information from educational sites:

Fungicide Application: Fungicides can be effective in managing apple scab. Applying them at the right time is crucial, typically from the green tip through midsummer. Homeowners can apply fungicides to small trees if they follow the label instructions carefully.

Cultural Practices: Planting disease-resistant varieties is the best long-term solution to prevent apple scab. Pruning and training trees to allow good air circulation can also help reduce the disease’s impact. More information is at this link:

Apple Scab | Yard and Garden (iastate.edu)

Leaf Litter Management: The fungus overwinters in fallen leaves, so cleaning up leaf litter in the fall can reduce the inoculum for the next season.

Remember, it may take several years to control apple scab, and repeated infections can weaken the tree.