Ash Yellows Disease and Anthracnose on Sugar Maples

For more information call Bartlett Forestry and Wildlife, LLC, 802-291-0179

Ash Yellows Disease:
This problem showed up in Vermont in the 1980′s. It is caused by… mycoplasmalike organisms which invades the tree systemically. This means the vessels that transport food and water from the leaves to the roots are invaded. Quite often the infected trees will show yellow – curled up leaves the first year. Sucker sprouts or small branches will begin to grow off the main trunk after a few years. A split in the bark of the tree near the trunk may appear in time. Branches will begin to die after the 3-5 years. It seems to take 8-10 years to slowly kill the ash tree. This disease is very common in Windsor County Vermont and can seen in woodlots and downtown street trees. White ash and green ash are both affected in Vermont. Currently there are no treatments to stop the problem. Ash trees that are being grown in woodlots for timber should be harvested at the first sign of the disease before they develop decay. This problem is not related to the Ash Borer insect that kills ash trees in states west of Vermont. Many of Vermont’s ash trees have already died from Ash Yellows and many more will be die before the Ash Borer gets into the state.


Maple Anthracnose:

Pathogens: Gloeosporium spp.
Several species of fungi cause maple anthracnose. K. apocrypta causes necrotic spots or scorch-like blight on leaves of Japanese, Norway, red, silver and sugar maples as well as boxelder. Symptoms, which develop during wet weather in late spring and early summer, begin as discrete reddish-brown lesions (tan on Japanese maples). Lesions soon coalesce and kill large areas of the leaf. Young shoots and leaves may shrivel and blacken following infection. Severe infection may lead to defoliation. Discula sp. affects sugar and striped maples, causing brown to reddish brown lesions along or between leaf veins. Spore masses of the fungus can sometimes be found on lower leaf surfaces along veins during extended moist conditions. The fungus spreads from previously infected tissue in spring to new growth. This disease can be serious in rainy seasons. The rust colored spots generally becomes very visible on the leaves in August. The trees have produced food prior to this so it rarely causes permanent damage to the tree. It will however cause the leaves to drop prematurely and often before they turn their normal fall colors.