Pathogen
Pine needle rust is caused by the fungal pathogen Coleosporium (Sinclair and Lyon 2005). There are numerous species native to North America that can be responsible for the disease. Coleosporium is a heteroecious rust fungus, meaning it requires two botanically unrelated plant hosts to complete its life cycle. Specifically, the fungus infects two- and three-needle pines (Pinus spp.) and members of the Asteraceae family.
While the disease is often attributed to C. asterum, this species is non-native in North America and likely represents a species complex native to Asia (McTaggart and Aime 2018). Across North America, C. delicatulum, C. montanum, and C. solidaginis are common on both pines and members of the Asteraceae (McTaggart and Aime 2018). Numerous other Coleosporium species have been reported in North America on pine but these require renewed taxonomic evaluation to determine their accuracy (Farr and Rossman 2026).
Hosts
Among pines, Coleosporium can infect numerous native and non-native two- and three-needle pines (Sinclair and Lyon 2005). In the northeast, pitch pine (P. rigida) is the primary host, but the disease may be found on ornamentals such as jack pine (P. banksiana), mugo pine (P. mugo), Austrian pine (P. nigra), Scots pine (P. sylvestris), and Japanese black pine (P. thunbergii). Among the Asteraceae, goldenrod (Solidago) and aster (Aster) are the primary hosts, but numerous other members of this family can also be infected (Sinclair and Lyon 2005).
Symptoms & Signs
Symptoms of pine needle rust appear in early spring as reddish-orange spots on the needles of infected pines. Pads of fungal tissue swell at these sites and when the current season’s needles are elongating, the pads rupture, allowing flattened white spore-bearing structures (aecia) to emerge and release large volumes of spores (aeciospores). When the needle lesions are numerous, the tips can be blighted and may be diseased by other needle blight fungi (e.g. Rhizosphaera). Because the base of the needles remains green, infected needles are often retained in the canopy.
Aeciospores disperse to infect the foliage of aster and goldenrod (among other Asteraceae), producing orange spots and blotches a few weeks later. On these herbaceous hosts, Coleosporium produces urediniospores that can reinfect the plants over the course of the summer. Finally, in late summer to early autumn, the fungus produces additional spores (teliospores > basidiospores) that disperse to infect susceptible pines, thus completing the life cycle. Coleosporium can overwinter in both pines and Asteraceae (Sinclair and Lyon 2005).
Management
Despite its highly conspicuous appearance, pine needle rust causes only minor damage to infected pines and serious outbreaks appear to be uncommon in southern New England. If the disease is a continuous problem across managed landscapes, avoid planting asters and goldenrods near two- and three-needle pines. Chemical management to control rust diseases is notoriously difficult and is not recommended here.
Literature Cited
Farr DF, Rossman AY, and Castlebury LA. 2026. United States National Fungal Databases. USDA-ARS Mycology and Nematology Genetic Diversity and Biological Laboratory. Retrieved March 12, 2026 from https://fungi.ars.usda.gov
McTaggart AR and Aime MC. 2018. The species of Coleosporium (Pucciniales) on Solidago in North America. Fungal Biology 122(8): 800–809. https://doi.org/10.1016/j.funbio.2018.04.007
Sinclair WA and Lyon HH. 2005. Diseases of Trees and Shrubs, 2nd edn. Cornell University Press, Ithaca, NY.