Cultures of a destructive mold called Phomopsis strains that infect both crop and noncrop plants. One of the species of this genus, Phomopsis viticola, cause a plant disease called phomopsis or dead-arm. Usually, infections begin during early growth stages in spring. 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.
Another Phomopsis species, P. juniperovora, infects junipers, and is a particularly important pest of seedlings and juvenile plants in the nursery industry.