Pine trees in the mountains

In Calgary this fungus, a rust, is found mostly on Mugos. Other susceptible pine species include Jack, Lodgepole, Ponderosa, Austrian, and Scots pines.

Easily identified by woody balls formed on branches, they can be double the diameter of the parent branch. As with all rusts, a powdery orange (rust) colored surface appears, usually in June. This is the arrival of the spores. Unlike most rusts, this species does not need an alternative host, and can pass easily from pine to pine.

Spores move easily in the wind and infect young shoots. Months later small galls appear, but do not produce spores till the second year. Galls that grow all the way around a branch, usually kill that branch. Galls formed on the main stem of small Trees are at a place where it is easier for the trunk to break. When I find these galls, I remove them.