Health Protection, Southern Region
PINE NEEDLE RUST,
caused by Coleosporiumsp.
Importance. - Needle rust is most prevalent on young trees. The disease usually does not seriously damage trees, and is of most
concern in Christmas tree plantings and nurseries. Most two- and three-needle pines throughout the South are susceptible. Goldenrod, asters, and other
plants serve as the alternate hosts.
Identifying the Fungus. - The fungus has four stages. The aecial stage on the pine needles looks like small, white-orange "sacks."
Aeciospores infect the alternate host, which results in orange, powdery spores on the leaves. Later orange, cushionlike objects, called telia, are produced
on the underside of the leaf. The last stage (pycnial) looks like frosty, orange droplets on the pine needles.
Heavy pine needle rust infection. (Click for detail. JPG 47K)
Fruiting bodies of pine needle rust. (Click for detail. JPG 36K)
Identifying the Injury. - Infected pines often have white-orange blisters on the needles. Although these are actually fruiting structures
of the fungus, they are an obvious feature of infection.
Biology. - Pycniospores form on pine needles in the spring; then orange, aecial blisters form. The spores from the aecial blisters
infect the alternate hosts which produces urediospores on the leaf. These spores reinfect the alternate host, but not the pine. Later, telia form on the
leaves. These produce orange-yellow spores, which infect the pine.
Control. - No control is needed in forest stands. The alternate host can be reduced through mowing or the use of herbicides. This
would only be justified around highvalue areas, such as nurseries.