GUIDELINES FOR CONTROLLING EMERALD ASH BORER FOR THE CITY OF BAYFIELD AND ITS RESIDENTS

SNOW CLOUDS AND MAPLE LEAVES

SNOW PELLETS AND OAK LEAVES

Monday, 9:00 AM.  33 degrees F, wind W, light with strong gusts.  The humidity is down, at 72%.  The sky is overcast, with some dark, billowing snow clouds.  The barometer is more or less steady at 29.83".  It rained some last night which turned to snow pellets, and my unlined jean jacket was poor defense against the weather this morning.

   The emerald ash borer (EAB) is a beetle that infests only ash tree species.  It is of Asiatic origin and has caused the death of millions of trees in cities and woodlands in the Midwest in the last ten years.  'The vascular tissues of ash trees are destroyed by the feeding of tghe larval stage (borers) of the insect.  The adult itself does little damage.  It takes several years for infected trees to show damage, and at present, without treatment with systemic insecticides an infested tree will die within four or five years.
   Currently available insecticides or of relatively  low toxicity to higher organisms and are mostly retained in the tree they are targeted to or are bound in the soil.  There have been instances reported of toxicity to bees but they have been rather poorly documented.  The USDA sets standards for use, and some chemicals must be applied by a licensed applicator.
   Chemicals, according to their types, are applied by injection into the tree, by soil drench around the base of the tree, or by spray application to the trunk of the tree.  What methods and chemicals to use are a choice of the municipality or the home owner, and are based on many factors, including cost, ease of application and environmental concerns.
   Since detection of the insect is almost impossible before damage occurs to the tree, and the chemicals have a relatively short useful life span, chemical applications are not recommended until actual insect damage occurs in the tree or nearby trees.  Chemical control is usually good before the tree has lost 30% of its leaf canopy, and declines after that.  Once 50% of the tree is affected the chance of survival is slim.

   Infested trees, or trees within an infested location, must be treated every two years, and regardless of the cost of the initial treatment is bound to become expensive over time.  This factor should be balanced by the cost of tree and stump removal, which can be several thousands of dollars for a large tree, as well as the importance of the tree in th landscape.  For most chemicals, regardless of type or method of application, spring is the preferred time to apply.

CHEMICALS CURRENTLY LICENSED FOR EAB BY THE USDA

Xytect (imidacloprid) is applied to the soil as a liquid drench  by the owner, or by soil injection by a professional applicator.  It is sold as Bayer Home Advanced in larger stores .  As Optrol it is stronger, for trees over 15" DBH, and must be applied by a licensed applicator.  Zytect costs about $10 for a tree under 15" DBH and is the least expensive of the chemicals.

Transect (Dinotefuran) is used as a soil drench or bark spray.  It costs about $20 for a tree under 15" DBH, but bark spraying is a simple application.

Tree-age (Emmamectin benzoate) is injected into the tree by a licensed applicator.  It is highly effective and a good control for larger trees.

Tree-Azin (Azadirachtin), is an organic insecticide made from the African Neem tree, and is injected by a caplet system. It is the only registered EAB treatment in Canada.

   My recommendations at present for City of Bayfield trees are to consider bark spraying with Transect for the few good ash street trees it has.  A final decision can be postponed until EAB actually shows up in the area.  This would not be expensive and relatively easy to do.  I do not consider treating large trees in the Dalrymple Campground woods practical and if they become infested they will have to be removed.

   My recommendations to Bayfield homeowners is to consider the cost and landscape factors involved and make their own decisions.  Larger and more prominent trees may well be worth treating and aging, and home applications of the easier to use chemicals may be practical for smaller trees.  Dead ash trees disintegrate quivkly and must be removed before they become dangerous.