Scanning electron micrographs of Cronartium ribicola. Image courtesy of Brian Duarte in Dr. Richard Hamelin lab, Dept of Forest and Conservation Sciences. Left image: Cronartium ribicola having the telia structure on ribes leaves that occurs after the infection of the Ribes nigrum plant. The telia here are in the process of producing basidiospore from the teliospore structures on each telia. Basidiospores are the crucial spore type that eventually infect white pines. Centre image: Aeciospores of Cronartium ribicola on a Ribes nigrum leaf. They are all germinating to eventually infect the plant. Right image: Urediniospores of Cronartium ribicola on the Ribes nigrum plant showing the process of infecting the plant by extending a germ tube through the stomata to reach the host cells.