Ash trees, anthracnose and Emerald Ash Borer

Linn County Master Gardener, Claire Smith, shares the following about anthracnose and Emerald Ash Borer:

    Anthracnose – big word, hard to wrap your tongue around.  Anthracnose is a common foliage disease of shade trees in Iowa, including the ash tree.  Multiple inquiries to the Master Garden Hort-Line this morning were from folks whose ash trees were dropping leaves, an unusual occurrence in the spring.  A good guess would indicate that most of those folks were concerned that their wonderful ash tree had become infested with the Emerald Ash Borer.   Be aware that experts are seeing if the Emerald Ash Borer has invaded Iowa by crossing the river into the Northeastern portion of the state.

    A bit about each of these diseases: 

    Ash trees can be infested with anthracnose that is caused by a fungus.  There are a number of closely related fungi, but each is host specific to the tree it infects.  Often symptoms appear serious, but generally the damage caused is minimal and doesn’t seriously affect mature shade trees.  Symptoms include tan to black blotches; immature leaves becoming distorted from abnormal leaf expansion; young leaves dying and falling soon after a heavy infection.  If a severe infection does occur early in the growing season, the trees may defoliate and then a new set of leaves may emerge.  Following are some suggestions to decrease the severity of anthracnose and minimize its impact on your tree’s health:

–          Clean up and destroy fallen leaves:  use your lawn mower bagger

–          Prune the tree to remove diseased branches and properly dispose of them.

–          Prune to open the canopy for better air circulation. Fungi relish damp conditions. Pruning is generally not recommended now, but better to prune than lose the tree.

     The Emerald Ash Borer prefers Green Ash and Black Ash Trees, but will tackle any ash when the previous two mentioned have all been killed.  The borers emerge from early spring to late summer, but evidence may not be visible for up to a year.  Signs of infestation are D-shaped holes in the bark of the trunk and branches and shoots growing from the base of the tree which is the most telltale sign.  The beetle will effectively girdle the tree.  

Following are some suggestions to help reduce infestation and impact of the Emerald Ash Borer:     

–          Avoid planting ash trees

–          Learn the signs and symptoms of the Emerald Ash Borer

–          If camping, purchase firewood at or near the campsite but thoroughly inspect firewood prior to purchase

–          Do not bring extra firewood home with you.

     Maintaining a healthy environment for your trees and plants is of utmost importance.  A routine inspection of your yard and garden is necessary.  Discuss abnormalities with your local extension service, Master Gardeners, or a reputable garden center.  Pictures or actual plant samples are wonderful aids in diagnosing problems. 

REMEMBER THE LINN COUNTY MASTER GARDENER PLANT SALE THIS SATURDAY, MAY 16TH FROM 8:00 TO NOON IN THE EXTENSION OFFICE PARKING LOT AT 3279 7TH AVE. IN MARION.

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