As cool wet weather persists in Minnesota this year, a common leaf blight disease of shade trees known as anthracnose thrives and spreads. Anthracnose is a fungal disease that causes leaf blotches, leaf distortion, shoot blight, and leaf drop. This disease is caused by several related fungi that thrive in cool wet conditions. Ash, maple and oak trees are all commonly infected with anthracnose and symptoms of the disease have been seen on all of these trees this spring. Despite blackening of leaves and shoots, anthracnose actually only results in a minor stress on the health of the tree. Only young growing leaves and shoots are susceptible to infection. Mature leaves are relatively resistant to the disease. Once warm dry weather arrives in Minnesota, leaves will mature and trees will replace lost leaves with a new flush of growth. As long as cool wet weather persists, however, expect this fungal disease to spread throughout the trees canopy. More information can be found about this disease at the UMN Extension publication on anthracnose in shade trees.
Results tagged “anthracnose”
Michelle Grabowski, UMN Extension Educator
Clemson University - USDA Cooperative Extension Slide Series, Bugwood.org
Photo 1: Anthracnose on grape berries
Anthracnose thrives in warm, wet weather. In Minnesota, some vineyards see Anthracnose every year, and others rarely have a problem says University of Minnesota Grape Breeder Dr. Jim Luby. The Canadian researchers found Frontenac and Frontenac Gris to be resistant to anthracnose, Frontenac Blanc and La Crescent to be susceptible, and Marquette to be highly susceptible. Growers interested in trying new wine grape cultivars should learn about disease resistance to several grape diseases in addition to anthracnose. Downy mildew, black rot, powdery mildew and Botrytiscan all be problematic in Minnesota vineyards. More information about disease resistance and culture of cold hardy grapes can be found at the University of Minnesota Cold Hardy Grape webpage.