Plant Pathology: Extension: Plant Disease Library

Phomopsis

Important diseases:  Tip blight of Junipers, Canker of Peach, Phomopsis blight of Eggplant.

Phomopsis is most commonly know for causing tip blight on junipers, but it also causes stem galls on woody ornamentals and stem cankers on numerous hardwoods and fruit trees.

 

Phomopsis infection kills the current year's growth on juniper branches. Branch tips turn brown to gray and Phomopsis fruiting structures (pycnidia) can be seen on the killed growth. Stem cankers caused by Phomopsis may girdle and kill stems of numerous woody ornamentals and fruit and landscape trees. Cankers are often sunken, reddish in color with a distinct delineation between healthy and killed tissues. The fungus produces abundant fruiting structures along the killed tissue. Round, rough stem enlargements or galls may also be caused by Phomopsis. Eggplant lesions are pale brown, sunken, with pycnidia arranged in a circle.



Black, globe-shaped pycnidia are immersed in host tissue and erupt through the epidermis. Pycnidia have a small opening (ostiole) at the apex from which spores are often extruded in cream to yellow-colored spore tendrils under moist conditions.

Two types of spores are produced within Phomopsis pycnidia; alpha and beta conidia. Alpha conidia are single celled, clear, and oval to fusoid (football-shaped). Beta conidia are single celled, clear, long and thin with a characteristic curve or bend present. Both spores should be present to confirm Phomopsis identification, but only one spore shape may be present in certain instances.