Dothistroma Needle Blight Plant Pathology Dothistroma Needle Blight Dothistroma needle blight is caused by the fungus Mycosphaerella pini. Common hosts include Austrian, ponderosa, and mugo pines. Infection usually occurs first on the lower branches of the tree and spreads upward. Diseased needles drop prematurely, the older ones first.
Infected needles show yellow to reddish-brown spots or bands that extend around the needle.
Needles eventually die from the area banded to the tip. Dying needle tips may be evident 2-3 weeks after bands appear. After death of diseased needle tissue, small black fruiting structures of the fungus break through the epidermis. Symptoms are similar to brown spot needle blight, but Dothistroma occurs primarily on Austrian and ponderosa pine and brown spot is more common on Scots pine. The fungus enters needles through stomata and survives mainly on infected needles on the tree.