A common disease among eastern hard pines is eastern gall rust. In the U.S. the range of this disease includes Minnesota eastward to the New England states and south to the states bordering the Gulf of Mexico. Host trees include Scotch, Austrian, Jack, Pitch, Shortleaf and Loblolly pines, each within their respective range. Red, black and white oaks are alternate hosts for this fungus which requires more than one species of host to complete its life cycle.
The fungus, Cronartium quercuum, causes eastern gall rust. In the spring infected trees will have bright orange, globe-shaped galls, aesciaspores from these galls will be eventually become airborne and become attached on the underside of oak leaves. Urediaspores form on oak leaves and can spread and infect other oak trees. Eventually brown, hair-like teliaspores form and replace the urediaspores on the oak leaves. Telia mature over the winter in northern regions and summer in southern regions, at maturity they release the final stage of their life cycle; basidiospores, which become airborne and seek pine trees to infect. This results in the globose swellings on stems of infected pine trees.
High relative moisture conditions with ample free water abounding are conducive to the spread and growth of eastern gall rust. Extended spring frosts or very dry spring seasons both will limit the production and dissemination of spores. Conditions during the development aesciospores and basidiospores will mark the difference between epidemic spread and limited infections.
Care needs to be taken to control the spread of eastern gall rust amongst nursery stock, all plants must be carefully inspected and monitored. Individuals found to be infected must be removed at once. Control in forest settings is difficult and management mostly consists of thinning, removing infected trees and managing for stemming the spread of spores. If you suspect any of your oak or pine trees to be infected with eastern gall rust or want to take preventative measures contact your arborist and visit: https://www.savatree.com/tree-disease-treatment.html.