Wednesday, March 14, 2012

Yes, Kiss Your Ash Goodbye

Emerald Ash Borer larval feeding injury
About nine months ago, this blog described purple traps hung throughout the Delaware Valley which are designed to detect an important pest … Emerald Ash Borer (EAB). The traps were not successful in detecting this insect but a sharp-eyed arborist was. Last Friday I got a call to look at some ash trees that were ravaged by woodpecker feeding. Beneath the bark, signs of larval tunneling were obvious. A few days later, Pennsylvania Department of Agriculture entomologists visited the site and verified that this was indeed Emerald Ash Borer.

Bad news for ash trees.

You can read the blog of June 11 last year and get the story … nothing has changed except that a detection has been made about 100 miles east (Warrington, PA, Bucks County) of the leading edge of the Pennsylvania EAB infestation. About the only good news is that a tremendous amount has been learned about this insect in the last 10 years. See this Penn State site or this National EAB site for solid, research-based information. The PSU “Frequently asked questions” feature is a good starting place.

For tree owners, the time has come to consider the fate of your ash. Depending on who’s counting, this insect has killed between 40 and 50 million trees between Michigan and….. Warrington. It is in 15 states and two Canadian provinces. It’s a tree killer. Infested ash die.

Individual trees can be protected with insecticides. Some can be applied by homeowners but, from what I read, the best product is available to arborists only and has to be injected. Upside? Two years of control.

Another hopeful thought is that entomologists now have several parasitoids, (bug killing bugs) that may provide some control of EAB… and perhaps the site recently detected would be a release site for them. That would be nice. Cross your fingers.

But don’t expect predators to catch up to EAB in Bucks County before a lot of damage is done. For now, learn to recognize ash . Think about whether it is really important to preserve those that you see. It is not practical to treat every ash tree. Remember, treatment provides only temporary protection, not immunity or a cure.

Those considering do-it-yourself treatment will find instructions here

Anyone following the story of Emerald Ash Borer knew that it was only a matter of time before this insect would be found killing ash trees in eastern Pennsylvania. Maybe this knowledge lessened the blow a bit. Also, those who closely observe tree and pest interactions know that this is one of many associations between an insect (or disease pathogen) that results in catastrophic impact on a species. See Dutch Elm Disease, Chestnut Blight or Hemlock Wooly Adelgid. More recently, Thousand Cankers Disease of Black Walnut.

I never paid much attention to ash trees until EAB arrived in Pennsylvania five years ago. Now I see them everywhere. Not for long.


Anonymous said...

As you mentioned, EAB has been expected for some time, but still comes as a shock to eastern PA residents. I work with cities all across the country who have come to terms with managing this pest. It is manageable, but as you so correctly point out, a sense of urgency needs to exist near the infested area (15 miles). The research via MSU and OSU is pretty conclusive that TREE-age, adminstered by an Arborist will provide two years protection by label, and researchers are actually seeing longer control. The evidence is also clear that if the canopy is less than 50% in decline, a tree may be saved, but that is a fall back strategy, I higly recommend not waiting until this point. The confusion lies around the cost to treat versus the cost to remove, and I educate on this subject daily. Average citizens can expect to pay about $80-$120 for a 10" diameter tree, for two years of protection, while cities treating in house regularly treat that same tree for about $30, remember, that's for two years of protection.
I have found most cities will re-treat during the 3rd year. Also, it is well documented that the cost to remove and replace an average 17" Diameter city tree ranges from $750-$1000., while that tree can be treated for an a cost of $59. all costs included. I mention that because it means that a city can treat it's trees for decades before reaching the cost to remove and replace, and they can keep their urban canopy even if they decide to slowly reduce dependence on ash. This will save budgets, and quality of city life.
I say with some authority, we can learn from what has been experienced west of here. I encourage folks to go to the national EAB website and read for themselves which products work best, and which work even when the EAB attack peaks. look at the "Insecticidal Options" bulletin. BTW, TREE-age is known as emamectin benzoate in this multi-university report.
Finally, another important note: EAB only feed and reproduce on ash species, so as untreated ash populations fall, so too will EAB, and this will likely result in reduced frequency of treatment as the pest peaks and then drops in numbers. This be a decade, but if residents hang on, the options are brighter. You don't have to kiss your ash goodbye, Thanks...

Warren A. Jacobs said...

In response to anonymous: Something to take into consideration before treating ash trees is that emamectin- (TREE-age)- is only registered for use by macroinjection. Because this technique causes an injury that must be walled off by the tree, using it when there is no threat of EAB will do more harm than good. Repeated unnecessary treatments could result in a situation where when the time comes that the trees ARE threatened, they will be less treatable. MONITORING is the sensible course of action now, until EAB is known to be within striking distance.

Scott Guiser said...

Thanks for the insights