Cedar apple rust is a fungal disease that can wreak havoc on apple trees. It is caused by a pathogen that requires a complicated cycle involving another species, in this case the red cedar. Known as an alternate host, different disease stages inhabit the two species in a cycling. Since both plant types are necessary, apples and cedars, one strategy is to eliminate red cedar from the orchard area. White cedars are not susceptible. Strategies to prevent the disease include fungicide application, removal of red cedars from the vicinity, or choosing a rust resistant apple variety.