White Pine Blister Rust

White pine blister rust Common name White pine blister rust Causal agent White pine blister rust is a fungal disease caused by members of the genus Cronartium and the family Cronartiaceae. Scientific name Cronartium ribicola Symptoms & Signs Reddish-yellow spots appear on the pine leaves with lasting cankers on the branches. The cankers appear within two years of the infection, resulting in a chlorotic, stunted plant. It secretes a sticky white or orange sap containing fungal spores as well. The dead branches on the top of pine trees turn red, giving them a distinct appearance. Alternatively, on the currant and gooseberry plants, the symptoms manifest as small orange pustules on the underside of the leaves with chlorotic leaves that fall off prematurely. Transmission It transmits through spores that travel to other plants via wind, water, and contact. Cool, wet temperature favors the pathogen’s growth, helping spore germination and spread. Time of concern Late summer and early fall Common hosts White pine Sugar pine Limber pine Currant Gooseberry