About Pileolaria brevipes Berk. & Ravenel
Pileolaria brevipes (common name poison ivy rust) is an autoecious fungus species belonging to the order Pucciniales. This fungus parasitizes two Toxicodendron species: Toxicodendron diversilobum and Toxicodendron radicans. The rust’s color comes from its asexual spores, which are called urediospores. In spring, poison ivy rust infections become visible as light pink to dark red swellings on leaflet veins or petioles. By late June, these swellings have darkened to brown and increased in size. Infected leaflets or leaves typically develop a curled shape and often become wilted. Infected individual plants are less likely to flower than neighboring uninfected plants of the same genus. Two damaging arthropod species associated with Toxicodendron species are Epipaschia zelleri and the poison ivy sawfly.
