Increased Occurrence of Pitch Canker in White Pine this Summer

By on July 15, 2020

If you notice oozing clear or red resin and discolored needles on your pine trees, pitch canker could be the culprit. Pitch canker is a widespread fungal disease of pines in North Carolina. Longleaf, loblolly, and slash pine are commonly infected, but this native disease can impact any southern pine. While it is not commonly found on it, this year there is increased occurrences on eastern white pine (Pinus strobus) in western N.C.  So far, it has primarily been seen impacting trees along forest edges, but as the season progresses, it is likely to impact others. This increase of pitch canker on white pine is likely due to ideal environmental conditions, such as excessive rainfall and cooler temperatures. If you have been feeling blue due to heavy rain recently, you aren’t alone!

“Heavy amounts of rainfall and cooler temperatures are ideal conditions for pitch canker, which are likely the reasons for the increased prevalence of pitch canker this year.”

Brian Heath, Forest Health Specialist, N.C. Forest Service

Pitch canker is an infections that causes cankers form and red or clear resin to accumulate. Image: USDA Forest Service – Region 8; Bugwood.org

There are several signs and symptoms that you can look for to determine if your trees have been harmed by pitch canker. Pitch canker causes infections that encircle branches, exposed roots, and main stems. This infection creates cankers from which resin (pitch) accumulates. Diseased bark often turns tan to chocolate brown in color, and removal of the bark exposes yellowish sapwood that is resin-soaked. Branch tips wilt due to decreased water flow, and needles turn yellow then brown. Eventually, needle clusters may fall off, leaving bare branch ends. Dieback, or branch death within a canopy, is common and can eventually lead to tree death. To add insult to injury, infected trees are often attacked by Ips engraver beetles, which can cause more dieback in the tree branches.

Even though pitch canker is damaging on its own, there are often accomplices that help it attack trees! The fungus may enter trees through wounds caused by weather damage, insect feeding, or even something as simple as a bird breaking a branch. Wind or insects also carry spores produced by pitch canker to new trees where they enter the wounds and begin a new infection.

Pitch canker can cause needle discoloration, dieback, and slower growth in infected pine trees. Image: Paul A. Mistretta, USDA Forest Service, Bugwood.org.

Unfortunately, little can be done to prevent or treat pitch canker. Since the fungus enters a tree through lesions, one should avoid wounding trees and creating fungal entry points. Proper tree care can also help trees overcome the infection once the fungus enters. There is no effective fungicide treatment for pitch canker. While pitch canker can cause death, not all infected trees become severely diseased, and some may even recover on their own. Since there is a possibility of recovery, you should use a conservative approach to removing diseased trees. Removing symptomatic branches may also help improve the aesthetic of the trees.

If you think that your trees have signs or symptoms of pitch canker, your NC Forest Service County Ranger can provide correct identification and advice. To find your County Ranger, visit: http://www.ncforestservice.gov/contacts/contacts_main.htm.

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