Rusts - Western Gall Rust TYPE HOSTS  DESCRIPTION Western Gall Rusts - Endocronartium harknessii Helen Atthowe - Missoula County Extension Helen Atthowe - Missoula County Extension Lodgepole, mugo, Scots, Austrian and ponderosa pine. Rough, globular galls on trunks or branches of pines. When the fungus is fruiting the galls are yellow or orange.  Galls rupture to release yellow-orange spores on current year's shoots. Controls: Rust infection is favored by prolonged periods of wet, cooler(60-65ºF) weather in spring (May/June) when galls rupture and produce yellow-orange powdery spores. Cultural:  Keep irrigation off of needles, branches, and trunk. Maintain plants for good air circulation. Prune to maintain good air circulation. Mineral: Sulfur sprays can be effective if sprayed preventatively when rust infection periods occur when yellow-orange galls are visible in wet weather.
Missoula County Extension Office; Missoula, Montana 59808 - Updated for 2006