Quick Decline of Macadamia Trees: Association with Phytophthora capsici

Some macadamia trees in commercial orchards in Hawaii showing quick decline syndrome had bleeding from the trunk. Phytophthora capsici was isolated from c. 67% of such sites, and was shown to kill branches of artificially‐inoculated healthy macadamia trees. The pathogen was detected in both diseased and apparently healthy bark and isolated from wood 80 mm away from the bark. Results suggest that trunk infection by P. capsici may lead to girdling and rapid decline, and attract insects which then cause some bleeding by making wounds at the sites of recent infection.