Ash Anthracnose

Ash Anthracnose becomes a problem on Ash trees when the conditions are favorable: moist and cool. The moisture helps spread the spores in the spring and the cool weather aids the disease development on the leaves. Once the weather becomes less favorable, spore production and disease development will be greatly reduced. Ash trees that become infected several years in a row may become stunted. Steps can be taken to minimize subsequent infections.

Photo credit: Manitoba Agriculture, Rural and Food Initiatives

  • Fallen leaves should be raked up and destroyed to minimize further infection
  • Fertilizing with a high nitrogen will promote optimum refoliation
  • Apply a protectant spray. Timing is crucial and three treatments are necessary. Make certain labels are listed for Ash Anthracnose.
    • 1st Treatment: Apply when buds are beginning to swell, right before buds break
    • 2nd: Apply when buds show green tips
    • 3rd: Apply when leaves are half grown