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Pests in Gardens and Landscapes

Pest identification and confirmation—Phytophthora root and crown rot

Trees infected with Phytophthora spp. may decline over a period of years before eventually dying or they may be killed in a single season. Slow decline occurs when the roots are attacked; rapid decline occurs when the crown or basal stem is attacked and girdled in a single season.

If bark tissue is carefully cut away, red-brown streaks or zones can be seen in the inner bark and outer layer of wood. No fungus mycelium is visible in the tissue affected by Phytophthora, distinguishing this disease from Armillaria root rot.

Discolored wood of Phytophthora infection
Discolored wood of Phytophthora infection

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