Lophodermium needlecast in pines
Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.
This disease can kill red pine seedlings and causes browning on Scotch pines in the spring. Scotch pines with needles showing brown spots with yellow margins, yellow needles or brown needles, especially at the bottom of the tree, are probably infected with Lophodermium seditiosum.
The dead needles will fall off the trees in June, July and August, and these dead needles will continue to support fungal reproduction by allowing the fruiting bodies to develop and the spores to disseminate throughout the trees. Trees look as if they are making a comeback since the new buds break with a green flush; however, these new needles will become infected from August to October from the spores issuing from the fruiting bodies on the dead needles. The fungus will stay in those healthy looking needles all winter until spring, when, again, those needles will begin the process of yellowing, browning and dropping off.
Even though we see the symptoms of Lophodermium in the spring, the most important time to protect trees is in late July throughout the summer and fall, especially if these months are warm and moist. Apply a registered, preventative fungicide three or four times, once every two to three weeks from late July through October. Plant long-needle Scotch pines, which are more resistant, such as those from Germany, Belgian, Poland and Czechoslovakia. Make sure all the older pines have been removed from windbreaks near nurseries or plantations. These pines can serve as sources of fungal spores.