A small green insect, the Emerald Ash Borer, has been alarming Minnesota property owners for the last year. Afraid they will lose valuable mature shade trees, they come to Dundee to ask what they can do for their ash trees. Is it worthwhile to do anything at all?
The answer is an emphatic “YES!”
First, buy and use only local firewood whether you have a property with ash trees or not. Hennepin and Ramsey Counties are in firewood quarantine. Emerald Ash Borer is spread through wood products, most commonly firewood, so responsible acquisition and use of wood products is a good way to help slow the spread of EAB.
Second, if you do have ash trees, keep them healthy. Water slowly, for a long time so the soil is drenched deeply when we get less than an inch of rain a week or during heat waves. Fertilize with a high quality tree fertilizer in the spring. Avoid damage to the trees from weed-whackers, lawn mowers, animals, or improper pruning. Drought-stressed, struggling, damaged trees are far more likely targets of EAB than are thriving ash trees so keeping trees healthy is another good way to slow the spread of EAB.
Finally, owners of established ash trees should treat the trees. A systemic insecticide called imidacloprid is available for home owners to use as a soil drench, a very easy treatment method. And the good news is that studies by leading Midwestern research universities show that properly administered imidacloprid can protect healthy trees, even when they are surrounded by affected trees. Dundee will be happy to answer questions about products and methods of protecting ash trees. Home owners should measure the circumference of the trees’ trunk at chest height. That measure indicates the amount of insecticide needed for the tree.
Minnesota will lose ash trees - there is no doubt about that. But you don’t have to lose your tree and your neighbors don’t have to lose theirs. The month of May is one of the best times to treat ash trees for Emerald Ash Borer. Help save Minnesota’s ash trees!
Prepared by Barbara Whipple, Dundee Nursery. April, 2010.
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