apple trees

Asked August 27, 2016, 4:03 PM EDT

I have a couple of apple trees the do not look very good, I have not been able to find out what I need to do. Do I need to spray these trees and if so what do I spray them with and when?

Cherokee County Iowa

1 Response

The spots on the apple leaves may be due to cedar-apple rust.

Cedar-apple rust is a fungal disease. The fungus requires both an apple or crabapple and a cedar (juniper) to complete its life cycle. Apple and crabapple cultivars differ in their susceptibility to cedar-apple rust. Some cultivars are susceptible, others are resistant.

On cedar, the fungus produces reddish brown galls that are up to golf-ball size on young twigs. During wet spring weather these galls swell and begin to push out bright orange gelatinous tubular structures. Wind carries fungal spores from these gelatinous structures to susceptible apple and crabapple cultivars.

On apples and crabapples, cedar-apple rust produces yellow spots on the foliage. Cedar-apple rust on apples and crabapples is most severe when there are frequent rains in spring.

On a positive note, cedar-apple rust does not cause serious harm to apples and crabapples.

Products containing myclobutanil (such as Spectracide Immunox) are effective in controlling cedar-apple rust on apples and crabapples. Sprays must be applied from bud break until late spring when the weather becomes consistently warm and dry.