Phomopsis viticola, a genus of ascomycete fungi, cause a plant disease called phomopsis or dead-arm. Usually, infections begin during early growth stages in spring, occur in most grape-growing regions and are an important disease of grapes worldwide. This affects leaves, fruit, rachises, and shoots of a plant.
This disease causes the formation of lesions on shoots, leaves, and rachises, but also can cause fruit rot. It causes significant economic damage to grape vines. Infected leaves have small, yellowish spots with dark brown centers and may be puckered. With successive cool, wet springs, the inoculum will build up and infections will become more severe over time. Early detection of the pathogen in the vineyard is therefore crucial for its control.