In the West, fruiting bodies may form, mature, and release conidia during the same growing season. Conidia are dispersed and infection may occur from May to October. In the Central States, fruiting bodies of the fungus are formed in the late fall, but they do not mature and produce conidia until the following spring. dearnessii are usually a greenish-brown color. septospora are translucent whereas the conidia of M. Both fungi have conidia that are septate and similar in shape and size however, the conidia of D.

The two diseases have similar symptoms, and the asexual fruiting bodies of the two fungi split the epidermis of the needle in a similar fashion. Ascospores are hyaline, fusiform, and 11-14 x 2.5-3.5 microns.ĭothistroma blight can be mistaken for brown spot needle blight. Pseudothecia of the sexual state are produced on dead needles. The thin-walled conidia are hyaline, smooth, 1-5 septate, short clavate to long filiform, 10-32 x 1.8-3 microns and have a rounded apex and truncated base. 4-4) are exuded from the fruiting body in a white or pink sticky mass. The epidermis characteristically is split longitudinally along two sides of the fruiting bodies, and a fragment of the epidermis adheres to the top.Ĭonidia (fig. Symptoms on seedlings are similar to those produced on established pines.ĭark fruiting bodies are visible with a 10 x hand lens in the bands and spots on the needles. The second-year needles drop first, before the current-year needles.Ĭurrent-year needles of Austrian and ponderosa pine are initially resistant to infection, but they become susceptible in mid-July. Needles may develop extensive necrosis 2 to 3 weeks after the first symptoms appear. Symptoms of Dothistroma blight on needle.Īlthough the bases of infected needles remain green, the ends of infected needles usually turn pale green, then yellow, and finally brown.

Needles on lower branches of Austrian pine affected with Dothistroma blight.įigure 4-3. These reddish bands are most distinctive on pines in the West, where this disease is often referred to as 'red band' disease.įigure 4-2. The spots and bands on the needles turn brown to reddish brown (fig. Look for yellow or tan spots and deep-green bands. In the Central States, symptoms develop in the faIl (October or later) of the year that the needles are infected. On established pines, infection is most severe on the needles in the lower crowns (fig. These epidemics have resulted in unmerchantable Christmas trees, reduced effectiveness of windbreaks, and increased maintenance costs in park and landscape plantings. In plantations in the Central States, however, epidemics have developed within 5 years of outplanting with infected nursery stock. Scirrhia pini), the sexual state of the fungus, has been found only in Alaska, Oregon, and California.ĭothistroma needle blight does not seriously damage pine seedlings in nurseries. The fungus occurs in 21 States, including Alaska (fig. The most frequent hosts are Austrian, mugo, and ponderosa pines in the Central and Eastern States and lodgepole, Monterey, and ponderosa pines in the West.įigure 4-1. pini), affects 20 pine species and hybrids in the United States. 680, 184 pp.ĭothistroma needle blight, caused by the fungus Dothistroma septospora (syn. USDA Forest Service, Agriculture Handbook No. Glenn W Peterson - Plant Pathologist (retired), Rocky Mountain Forest and Range Experiment Station, USDA Forest Service, Lincoln, NE.Ĭordell C.E., Anderson R.L., Hoffard W.H., Landis T.D., Smith R.S.

Austrian pine needle blight