Monday, January 9, 2012

It Was Only a Matter of Time

Ash tree by #1 tee
If you have kept up to date with Elcona's monthly newsletter, it should not come as a surprise that a majority of our Ash trees are now showing signs of poor health as a result of the Emerald Ash Borer.  For many golf courses and homeowners throughout the Midwest, this spells disaster.  Fortunately for us, we do not have a significant number of Ash trees on our property and the ones that we do have, are not vital to the layout of a particular hole.

Click for larger view
Emerald ash borer (Agrilus planipennis) is an exotic, invasive woodboring insect that infests and kills native North American ash trees (Fraxinus spp.), both in forests and landscape plantings. Just like chestnut blight and Dutch elm disease before it, EAB is capable of eliminating an entire tree species from forests and cities throughout the land. This makes it one of the most serious environmental threats now facing North American forests.

Emerald ash borer was unknown in North America until June 2002, when it was discovered killing ash trees in southeast Michigan and neighboring Windsor, Ontario. It was probably imported into Michigan via infested ash crating or pallets at least 15–20 years ago. Since its accidental importation, EAB has infested and killed millions of trees in southeast Michigan, northern Indiana and northwest Ohio.

Adults emerge from late May through early August, with emergence peaking in early July. As adults emerge, they leave small, distinctly D-shaped exit holes (see photos) in the trunk and main branches, which is a sure sign of infestation. EAB larvae are white with a long (about one inch when mature) narrow, segmented abdomen that is also flattened, which gives them the appearance of small tapeworms. 

D-shaped exit hole
Adults are elongate, half inch-long beetles with striking, metallic green coloration. Females produce about 50 to 100 eggs, which are laid individually on the bark surface or within bark cracks and crevices. Observations indicate that higher branches and upper portions of the trunk are colonized initially, making it difficult to detect early infestations.As larvae hatch, they tunnel into the tree, where they feed through the summer and early fall on the phloem and outer sapwood, excavating S-shaped, serpentine galleries just under the bark. The larva is the damaging stage, girdling the tree as it tunnels under the bark where it feeds primarily on phloem and xylem tissue. This disrupts the flow of carbohydrates and water between the canopy and roots, which results in canopy thinning, branch dieback, and finally tree death, typically within two to four years of initial infestation.

The end result of  Emerald Ash Borer damage.

All photos were taken of Ash trees on Elcona's property.  Many of the facts in this post came from a fact sheet published by Ohio State University.  A link to the sheet is below:

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