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Published July 23, 2009, 09:11 AM

Own an ash tree? Follow these tips

Emerald ash borer remains a source of buzz around the state this summer and concerned homeowners want to know what they can do to protect their ash trees from this new invasive pest.

Emerald ash borer remains a source of buzz around the state this summer and concerned homeowners want to know what they can do to protect their ash trees from this new invasive pest.

To make it easier for residents to determine the best course of action, scientists from the Minnesota Department of Agriculture (MDA), Minnesota Department of Natural Resources and University of Minnesota Extension offer the following tips:

1. Timing is everything. In Minnesota, experts advise that treatments be conducted in mid-autumn or late spring. The treatments target adult emerald ash borers, which are active in the summer. To ensure that the product is in the leaves by the time the adults emerge to feed in early to mid June, product is most effective when applied several weeks in advance.

2. Consider whether the tree is worth protecting. Trees enhance property value and aesthetic value, but in some cases it may be more cost-effective to replace a small or struggling ash tree than it is to pay the recurring cost of protective treatments (typically between $50 and $200 for each treatment).

3. Don’t start treatments until the pest is near. If you have a high-value ash tree you want to protect, the rule of thumb is to start treatments only after an emerald ash borer infestation is confirmed within 15 miles of your property.

4. Select the treatment option that fits your circumstances. There are several products available to protect your trees, and it is important to select the right one. While some products can be applied by homeowners, others can only be applied by licensed commercial pesticide applicators. Ash trees greater than four feet in circumference should be treated by a professional tree care company. Also, if you live in an area of sandy soils, have a shallow water table, or your tree is close to a street gutter, it may be best to go with a commercial applicator to avoid unintended environmental impacts.

5. If you do it yourself, read and follow the product label. Minnesota law requires anyone using a pesticide, whether the applicator is a homeowner or a commercial applicator, to read and carefully follow the label instructions and advisories. This rule protects you, your family and Minnesota’s natural resources.

6. If you hire it out, pick a reputable company. In some states, the arrival of emerald ash borer was followed quickly by another kind of pest – one that tried to scam homeowners into paying for unnecessary tree treatment or removal. While MDA has not heard any reports of out-of-town scam artists taking advantage of Twin Cities homeowners, it is always a good idea to check the qualifications of any company you hire to do tree work. For emerald ash borer work, make sure that the company and the workers doing the treatment are Minnesota-licensed commercial pesticide applicators. Ask the workers to show you a valid license, which should include a special certification for ornamental and turf applications. As an added safeguard, consider hiring a locally based firm with a certified arborist on staff.

7. Don’t dump the ash before its time. Generally it is not necessary to remove a healthy ash tree.

8. Careful with those trimmings. Homeowners who trim their ash trees this summer should give careful thought to what they will do with the branches and limbs. After all, emerald ash borer larvae can hide inside branches no thicker than your thumb. If your ash tree is infested and you move the infested branches to a different location, you may be helping the ash borer find new victims.

For the latest information about the fight against emerald ash borer, homeowners may visit MDA’s website at www.mda.state.mn.us or call the MDA’s Arrest the Pest Hotline, at (651) 201-6684 (toll free 1-888-545-6684).

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