What are the best ways to treat apple scab on yard ornamental trees of various types? I am aware of fungicidal sprays. Which are the best? Are there systemic systems that are applied to the ground at the base of the tree, thus avoiding toxic over spray?? Are there ornamental yard trees that are not susceptible to apple scab or similar type of disease? Thank you in advance for any information you can provide. Regards, Ted Moudry
Washington County Minnesota
According to the following University of Minnesota bulletin "spores are released so early in the growing season, that fungicide sprays must begin when the first green leaf tips emerge in spring. Sprays should be repeated until petal drop. If the tree is healthy and free of leaf spots at this point, further treatments are unnecessary." Some experts believe additional sprays can be beneficial, but the benefit is minimal.
Managing apple scab on ornamental trees and shrubs