Phytophthora Root Rot (fungus - Phytophthora cinnamomi): Infected trees have small leaves which are lighter green in color than healthy leaves. The leaves wilt and drop, eventually leading to complete defoliation of the tree. Twigs and branches die back. There is a light fruit set with small fruit. The fungus infects roots up to one-quarter inch in size, although it is the feeder roots that are primarily affected. These roots become blackened and brittle before they die.

The disease occurs if the pathogen is present in soil and if there is excessive soil moisture. Poor drainage can be a contributing factor to disease development. The fungus can be introduced to new areas by movement of infected nursery stock or infested soil. Soil on implements can also serve as a means for introduction of the fungus to non-infested areas. Fungicides should be used in combination with sanitation in the nursery and maintaining adequate drainage in the field.

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