In the spring fungus spores which are produced on this host are blown to apples where young leaves become infected during periods of wet weather. As the disease progresses, apple leaves turn the characteristic rusty orange color. While there are additional control measures for cedar-apple rust which will need to be carried out next spring, you might want to consider a few things which could be done at this time of year as part of a control program for this troublesome disease. While cedar- apple rust spores can still be blown from cedars further away, the number of spores can be drastically reduced if cedars within the prescribed distance are removed. If cedars are part of your landscape, and you want to maintain them, prune rust galls from cedar branches during the late winter.
Applications are especially important before rainy periods.
Several applications will be needed past the bloom stage to adequately protect susceptible apple tissue. Fungicides registered for use on apples that are effective for cedar-apple rust include various formulations of such fungicides as mancozeb. Captan is not effective for cedar-apple rust. Give us a call at the County Extension Office if you have questions about developing a disease management program for your orchard. Recommendations on this web site do not endorse any commercial products or trade names.