Pitch canker is caused by a fungus that creates a resin-soaked lesion in the inner bark and outer sapwood of southern pine species. Most often a nuisance, the disease can deform trees, suppress growth, and kill branches or occasionally entire trees. Contrary to popular belief, the pitch canker fungus is not carried or transmitted by insects; rather the fungus infects trees through wounds including but not limited to insect feeding sites.
The primary symptom of pitch canker is a resin-soaked canker (lesion). Small branches or twigs that are infected are often completely girdled and killed; killing of the terminal or uppermost branches is also very common. The fungus can also infect and cause perennial cankers on large branches, main stems, and even exposed roots. Flowers, cones, and seeds can also be killed.
Diseased bark will turn tan to chocolate-brown, and the underlying sapwood becomes yellowish in color and heavily pitch-soaked. Resin-soaking may extend all of the way to the pith in severe cases. Bark remains on the canker and sap will frequently flow out of the lesion and dry on the branch surface or on other understory plants. Pitch canker commonly occurs in close-association with fusiform rust galls.
Needles around cankers usually turn yellow, then brown and are killed; they are retained on the tree by dried sap. Green shoots may wilt and die, giving the appearance of a shepherd’s crook.
Little can be done to prevent or treat pitch canker. Avoid wounding trees, especially during cool wet weather. Proper tree care is important to help trees overcome infection. Use of fertilizers rich in nitrogen is often accompanied by a large increase in pitch canker incidence. Excessive nitrogen is responsible for the high incidence of pitch canker near exhaust fans of chicken and hog houses.