Chance to learn more about emerald ash borer

Emerald ash borer is a small, metallic-
green bullet-shaped beetle.

The past week I've been speaking to PMPs at CEU conferences about the emerald ash borer.  Many folks have asked why they've never heard about this pest. I guess that's because it's a relative newcomer to the state and its impact is just beginning to be felt.

If you are one of the many in our industry who has heard little or nothing about this insect, let me enlighten you. The emerald ash borer, Agrilus planipennis (EAB), is a wood boring beetle that attacks trees in the genus Fraxinus, which we know as ash. Since it was first discovered in SE Michigan in 2002 it has spread with alarming speed throughout the midwest.  In 2017 the first beetle was found in east Texas.

The EAB is probably the most devastating forest pest since chestnut blight.  In areas where it has been in place for 10+ years it has virtually wiped out every ash tree. Some fear that certain ash species may be on the edge of extinction thanks to the borer. We have every reason to think the same thing will happen in Texas.

Ash is not as common in Texas compared to Michigan and other parts of the Midwest; but it is an important tree, especially in areas along streams and river bottoms. And it's a very important tree if you have one in your backyard.

Not every one of you provide lawn or tree care services, but if you do you should keep your eye on this beetle.  Even if you don't "do trees" you can still provide a service to your customer by alerting them to the risk of this beetle if they have ash trees on their property.

Emamectin benzoate is an effective
treatment applied by certified applicators.

Currently, EAB has been found in Marion, Cass, and Harrison counties in far east Texas.  Most recently a well-established infestation of the borers has been found in west Tarrant county, just a few miles to the northwest of Fort Worth. Anyone who cares for an ash tree who lives within 15 miles of a known infestation should consider their trees at risk (this includes most homes in Fort Worth), and should consider having it treated.

A handful of insecticides can provide protection of an ash tree at reasonable cost. If you are interested in being on the leading edge of how to treat ash trees for EAB in Texas, there are three workshops coming up, sponsored by the Rainbow Treecare company (Rainbow makes one of the leading insecticides for EAB management). Two of the workshops focus on community EAB management strategies, and one will provide a general introduction to EAB. 

These workshops are webinars.  If you've never attended a webinar, it's a pretty cool, and easy, way to learn. You sit at home or in your office, link up to a website, and watch and listen. You will also have the chance to submit questions and interact with the speakers.  To read about the webinars and register, go to https://register.gotowebinar.com/register/2236702821873051149

Other places to learn more about EAB include:

• The USDA Emerald Ash Borer website is a great source of authoritative information about EAB.   
• The EAB Information Network is a multinational effort to assemble information about the borer including blogs and general information. 
• EAB University is part of the EAB Information Network and has recorded webinar sessions on a wide variety of topics from top researchers and arborists in the country. All classes are free.
• Emerald ash borer found in Tarrant County. Citybugs blog. Story of EAB discovery near Fort Worth.

I hope to write more about this beetle in the future. In the meantime, get out your tree books and read up on ash. Once you learn to distinguish ash you will be able to tell whether a customer's tree is at risk.

Elimination of tree holes for mosquito breeding

Tree holes near ground level are especially
attractive to the Aedes mosquitoes that may
spread Zika virus.

It seems you never know what interesting places and topics pest control will lead you. This week's rabbit trail for me was a discussion on how best to "fill tree holes" that are a common mosquito breeding site.

With the heightened interest in mosquito control and Zika virus this summer, tree holes are a significant problem. When a limb dies back or fails on a tree, the result is often a pocket in the tree that is capable of holding water. It turns out that such water-filled tree holes are perfect breeding sites for some mosquitoes, including Aedes albopictus and Aedes aegypti, the two potential Zika-carrying mosquitoes.

The standard mosquito control recommendation is to fill these holes to prevent their use for breeding. But how do we best eliminate such holes without hurting the tree?  Here are some practical suggestions on filling tree holes gleaned from colleagues and other reputable resources:

• Filling tree holes with concrete, gravel or sand is a no no. Gravel and sand may help hold water in the tree and promote decay.  Gravel and concrete pose a real safety hazard for arborists or tree owners when the tree eventually has to be cut down--and not good for the chain saws either.  Concrete also adds weight to the tree, and does not flex or bend, causing internal friction and damage to the tree over time.  
• Drilling drain holes to keep water from accumulating is no longer generally recommended, as it may open the tree up to further damage to health tissue, and infection. 
• If a tree hole does not hold water it may be providing wildlife benefits, providing a home for birds or squirrels(!).  On the other hand, tree holes may provide a nesting site for roof rats. 
• Not all tree cavities need to be filled.  However if a tree hole is retaining water or providing a breeding site for unwanted animals, expanding foam may be a good solution. This tool has been largely embraced by the tree care industry because it is lightweight and easy to carry into a tree and is safe for chainsaws.  It also excludes water and will flex and bend with the tree.  Some argue that foam is bad because water often finds it way in anyway and foam retards evaporation, but from a mosquito control perspective the benefits of sealing water-retaining holes probably outweigh the risks.
• As when using expanding foam indoors in a home, don't overfill a hole. Use a foam with a lower expansion ratio, and inject the foam slowly.  Because foams can be unsightly where they emerge from a cavity, you might want to consider a black tinted foam like Pur-black and/or consider smoothing off excessive foam overflow after drying.
• If rats or mice are an issue, using screen or or other pest control excluder materials in the filling may prevent their chewing their way back into the tree.
• It is not necessary to clean out decay from the cavity before filling.  And "tree paint" dressings are no longer recommended by arborists for fresh wounds on a tree.

Thanks to colleagues on the Ornaent Listserve for their interesting and enlightening comments on this question this week.  

BTW, since I've done it here today, referral to a commercial product or website is for informational purposes only and does not imply endorsement by me or by the Texas A&M AgriLife Extension Service.