How to Manage Pests

Pests in Gardens and Landscapes

Phytophthora root and crown rot— Phytophthora spp.

Infected trees or plants often wilt and die rapidly with the first warm weather of the season. Leaves may turn dull green, yellow, or in some cases red or purplish. Symptoms may develop first on one branch or stem then spread to the rest of the tree or plant. Darkened areas develop in the bark around the crown and upper roots. Gum or dark sap may ooze from the margins of the diseased trunk area. Reddish brown streaks or zones can be seen in the inner bark and outer layer of wood.

Identification

Solutions

The key factor in reducing the threat of root and crown rot is good water management. Good soil drainage is best provided before planting. Plant certified nursery stock on mounds made by working up the soil. Never cover the graft union with soil and do not water the crown area directly. If you suspect crown rot, carefully cut away affected bark at the soil line. Trees can sometimes be saved by removing soil from the base of the tree down to the tops of the main roots and allowing the crown tissue to dry out.

For more information, see the Phytophthora Root and Crown Rot Pest Note.

Phytophthora
Symptoms of Phytophthora infected plant

Gumming and reddening of wood
Gumming and reddening of wood


Statewide IPM Program, Agriculture and Natural Resources, University of California
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