A Coniothyrium SP. Causing Leaf Blight of Jojoba

SUMMARY

A pycnidial fungus, identified as a Coniothyrium sp., was isolated from leaves and stems of jojoba and other plans native to the Sonoran Desert and growing in a variety of habitats in southern Arizona below 1,370 m. The dark, immersed pycnidia are often formed in concentric rings both on leaves and in culture. The ellipsoidal, amber conidia are aseptate, thick-walled, and produced in cirrhi in the host. The fungus causes lesions on the leaves of both seedlings and mature plants. Field observations and laboratory and greenhouse tests indicate that wounding facilitates infection.