C. abieitis is an autoecious microcyclic rust, producing the telial stage on the needles of species of Picea.
Yellow transverse bands appear in the current year’s new needles. Linear orange-brown telia are produced in those bands on the undersides of the needles in late summer or autumn, and persist through the winter (Wilson and Henderson, 1966;Smith et al., 1988).
Related invasive species
- Chrysomyxa abietis
Related Farm Practice
- Light
C. abietis is a microcyclic rust fungus;an obligate parasite completing its life cycle on species of Picea (spruce). Only the current year’s needles of Picea are infected and those needles are shed early. Reported from northern Europe and Asia, the fungus is a Regulated Pest for the USA. It is absent from North America, where susceptible species are native, and Australia and New Zealand, where they are introduced. Although usually not a significant problem in its native range, because conditions are not favourable for heavy infections every year (Smith et al., 1988;Hansen, 1997), this rust could be more damaging as an invasive in other temperate areas. Due to the fact that small amounts of infection may be overlooked, accidental introduction could occur through importation of infected seedlings or young trees.
Infections only occur on the current year’s needles. Light-yellow spots appear at points of infection, usually merging to form deep yellow transverse bands across the leaf. If infection is extensive, trees or entire stands may appear yellow rather than green. Most of the infected needles are dropped the following spring, after telia have matured and sporulated (Murray, 1955;Wilson and Henderson, 1966;Mordue and Gibson, 1978).