Very few diseases traditionally afflict the red pine, according to the Cornell University Plant Disease Diagnostic Clinic. However, as more and more plantings of red pine occur in increasingly diverse areas, more pests and diseases emerge, compounded by a low degree of genetic variation to provide the species with a natural means of developing resistance. Of the diseases that affect red pine, several cause symptoms that you may observe on your tree's bark.
Several diseases can cause damage to the bark of the red pine. Despite the name, armillaria shoestring root rot shows symptoms on the bark of red pine: white fungal strands that spread under the bark and yellow mushrooms that form on the bark near the tree's base. Several canker diseases afflict the red pine; also caused by a fungus, these diseases create wounds in the tree's bark. Insect pests may also cause bark deformities or exacerbate existing lesions after infection by a disease.
Red pines were once numerous in the Northeastern United States and Eastern Canada and, today, are experiencing a population resurgence due to their economically significant use for pulpwood and softwood poles. As explained in the "Pocket Guide to Red Pine Diseases and Their Management," the close dense plantings of red pine, as well as the low degree of genetic variation, means that diseases can spread quickly, with economically devastating consequences.
If you notice damage or lesions on the bark of your red pines, first establish common problems for the red pine in your area. Carefully inspect the tree for additional symptoms. Notice if you see any needle dieback or decay in the root area. Look for insects or signs of insects, such as entry holes in the bark. A definitive diagnosis, particularly for fungal diseases, may require you to submit a sample to your local university extension's plant pathology lab.
Unfortunately, there is no treatment for the fungal diseases that cause bark damage in red pines. If your trees have been diagnosed with one of these diseases, it is best to have the tree removed before the infection spreads to other trees via windblown spores. More options exist for controlling insects that damage the bark of your trees. However, in all cases, good planting and maintenance practices prevent diseases and pests and eliminate the need for control.
The Michigan Department of Natural Resources recommends avoiding continuous plantings of red pine trees of the same age, suggesting incorporating trees of different ages and non-pine species during planting. Choose sites with the well-drained sandy or loamy soil preferred by red pines. Check trees for signs of problems to catch--and correct--any diseases or pest infestations early.