Apple Cedar Rust

The CAR fungus has a complex life cycle that requires two hosts, eastern red cedar trees and apple or crab apple trees. Throughout its two-year life cycle, the fungus produces three kinds of spores: aeciospores, teliospores, and basidiospores, each with a specific function. Spores produced on the apple trees do not infect other apple trees. Only the spores produced on cedar trees can infect apple trees. Likewise, only the spores from apples can infect cedar trees.