Chronic Apple Scab

Flowering crabs throughout the midwest usually drop their leaves early due to a disease called Venturia inequalis commonly known as chronic apple scab. The disease is most severe when humidity is high and temperatures are moderate during spring and early summer. Host plants include nearly all apple and flowering crab trees as well as others in the “Mallis” family.

Treatment options include:

• 1) Apply appropriate fungicides as a drench at bud swell, bud elongation and bud break
• 2) Fertilize the trees in spring or fall
• 3) Do nothing

If you elect to do (1) the tree should maintain most of its leaves until normal leaf drop in the fall.
If you choose to do (2) the leaves will still drop early but the tree will be better able to cope with the leaf loss.
If you choose to do (3) the tree will likely survive unless it is in poor vigor.

However you choose to deal with the problem, be sure to remove as many dead leaves as possible in the fall because that is where the disease lives in the winter.

“Doc”
American Lawn and Tree Arborist

Tags: chronic apple scab disease, early leaves, flowering crab trees, midwest trees, treatment options

This entry was posted on Thursday, September 17th, 2009 at 3:37 pm and is filed under Tree Care & Prevention. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.