Red-band needle blight occurs throughout the growing season and during wet periods. Initial symptoms include dark green bands on the needles, quickly replaced with brown or reddish-brown lesions. After infection takes place, it may take 3-6 months for symptoms to become visible. In late summer, infected needles may show dark green bands that appear water soaked. This symptom occurs briefly and is usually not detected.

Next, yellow to tan spots become visible and then eventually become larger, reddish-brown lesions banding the needle. The fungus produces a toxin that quickly kills the tissue at the infection site and causes it to turn purplish red, giving this disease its common name, red-band needle blight. Girdling lesions will result in needle tips dying while the bases of the needles remain green. By late fall, tiny, black fruiting bodies may appear in the bands or dead tissue.