Question: I have a pine tree infected with pine pitch canker disease. Is there any way to stop or control its spread?
B.D., Garden Grove
Answer: Trees with pine pitch canker, a fungal disease that infects only pines, have a dark, reddish, resinous pitch on the limbs or trunk. Branch tips and entire branches die and turn brown; eventually the tree dies.
The disease is transmitted by insects that attack branch tips and developing cones. The vast majority of pines are naturally infected or susceptible to this disease. The only pine that grows well in our area that has shown some resistance is the Brutia pine. However, most experts recommend against replanting pines that have been killed by pine pitch canker.
Before you assume it is pine pitch canker, you should have a laboratory analysis done by a trained plant pathologist.
There is no available effective control in the battle against pitch canker. There are, however, a variety of things you can do to prevent its spread to other pines, such as the following:
* Prune to remove infected tips, which will not eliminate the disease but can slow it down if the tree is lightly infected.
Prune pines only in winter. (Insects that spread the disease are less active at this time.) Be sure to disinfect pruning tools between cuts and between trees. (Inform any commercial tree service you use to do the same.)
* Provide good air circulation around your trees. Dense pine plantings are most severely affected.
* Avoid fertilizing infected pines or those close to infected pines because the resulting rapid growth can stress the trees and promote the disease.
* Try not to move diseased wood outside the infected area. Haul the resulting debris to a landfill or chip and use it on-site as a mulch.
Have a problem in your yard? University of California Cooperative Extension master gardeners are here to help. These trained and certified horticultural volunteers are dedicated to extending research-based, scientifically accurate information to the public about home horticulture and pest management. They are involved in a variety of outreach programs, including the extension's Master Garden hotline, which provides answers to specific questions. Call the hotline at (714) 708-1646 or send e-mail to email@example.com.
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