anthracnose

Anthracnose is a general term for fungal diseases that infect shade trees, shrubs, edibles and lawns. Common trees infected include dogwood, elm, maple, sycamore and white oak. Due to their size, Anthracnose is difficult to control on trees. Edibles infected include blackberries, raspberries, tomatoes and beans.

On ornamentals and edibles, the disease causes reddish-brown, black or tan spots on leaves and sunken cankers on stems and fruit. It can cause severe leaf drop and twig dieback, and leaf curl on young trees. It is most troublesome after spring rains. Anthracnose can infect roses in very hot weather and is often mistaken for black spot. Also see Leaf Spot.

Anthracnose is most common on cool-season lawns (especially creeping Bentgrass and Annual Bluegrass) suffering from heat stress in midsummer, but it can also occur in spring or fall. It leaves yellowing patches from 2 inches to 12 inches and grows slowly. The grass picks up a yellowish tinge and wilts quickly, looking like it needs water. Close examination shows rotting at the base of individual grass stems.

 

Solutions

Cultural Controls

On Ornamentals and Edibles

  • Whenever possible, plant resistant varieties. Contact your local cooperative extension for more information 
  • Clean up and dispose of fallen leaves and litter, materials where disease can overwinter.
  • Remove and dispose of infected branches after pruning.
  • Avoid severe pruning, which can result in vigorous growth more susceptible to infection.
  • Space plants sufficiently to maximize air circulation and increase sunlight for faster drying of foliage

On Lawns

  • Water efficiently, wetting the entire root zone (6- to 8 inches deep) and allowing the lawn to partially dry between irrigations 
  • Fertilize correctly. Low fertility can increase problems.  If unsure, have your soil tested.
  • Mow higher - Mowing too low can increase problems.