Phytophthora cankers usually originate at or below ground level but can occur higher above ground, especially where trunks or lower limbs have been wounded. The canker appears as a region of dark bark that often exudes red resin, which becomes brownish to white and powdery as it dries. Cutting away the superficial canker reveals an orange-tan to brown lesion, instead of the normal white or cream-colored tissues. The lesion may have a fruity odor when exposed. The lesion infects the inner bark and outer layer of wood, killing cambium and phloem. Discoloring rarely extends deeper into wood than the outer woody layer. Depending on the local conditions and rootstock, the tree may ward off the disease and the lesions may heal.
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