The spores germinate, penetrate the leaves and cause galls. The galls produce spores the second spring after infection occurs, completing the two-year life cycle of the fungus. Control Removal of Juniperus spp. Since spores produced on the cedars can be wind disseminated several miles, tree removal cannot be expected to give complete control. However, removing Juniperus spp.
Apple varieties differ greatly in their resistance to rust.
Following is a list of varieties of apples grown in the variety test block at The University of Connecticut's Experimental Orchard located at Storrs, Connecticut and their relative resistance to rust. M.ioensis 'Fimbriata' and bechtel crab, M. ionesis 'Plena' should be avoided if rust is serious in a particular location. Rust resistant varieties of hawthorn such as Cockspur Hawthorn and Washington Hawthorn are available. Several fungicides can be used to protect apples from cedar-apple rust. The materials should be applied as sprays at seven to fourteen-day intervals starting at the pink stage of bud development up to the middle of June.