How to Manage Pests

Pests in Gardens and Landscapes

Phytophthora root rot—Phytophthora citrophthora and P. parasitica

Phytophthora root rot causes a slow decline of trees. Leaves may turn dull green or yellow and may drop. The center of the root turns soft. Uptake of water and nutrients will be severely limited. The tree will grow poorly, stored energy reserves will be depleted, and production will decline.


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 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. Tolerant rootstocks may help prevent infection.

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

Brownish streaks
Brownish streaks in infected roots

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