Wednesday, November 28, 2012


Today I was working on a brochure that we'll be producing that will help educate the public regarding the implication of Emerald Ash Borer (EAB) in our communities.  With EAB (native to Asia) being found in Janesville this year, there should be plenty of concern about what this pest will do to our ash (Fraxinus sp.) populations in our community, state and nation.  The metallic green, adult borer seen above is only 1/2" long and 1/8" wide and was first found in Michigan in 2002.  While the adults do little damage, it's the larval stage below that consumes the inner bark and phloem of the tree, creating the serpentine (S-shaped) galleries seen in the second photo down.  This nibbling essentially cuts of the flow of water and nutrients in the tree, causing dieback and death thru starvation.  It's thought that once this larval stage is present in the tree, it takes about three years for the tree to die.  I was at a symposium recently in the Milwaukee area and talked to the Parks Manager for West Bend (WI).  He said that EAB was found three years ago in their community and the devastation and loss of ashes in unbelievable.  He mentioned that they can't even keep up with ash removals in their parks.  The overplanting of ash in many communities is becoming a liability for sure.  On a trip to Michigan six years ago, I saw the effects of EAB and the scale of ash death was quite noticeable and depressing.  Most of these blog images were taken from the internet and were supplied by various universities and government agencies for education.  The internet has lots of information on EAB above and beyond what is presented here.

The most visible sign of EAB infestation is significant crown dieback in the ash (Fraxinus).  It is important to first identify and locate any ashes on your property for examination.  There are many online references for proper identification or an arborist could ID your ashes for you as well.  There may be epicormic sprouts (suckering) on the tree, bark slits and the characteristic 'D' shaped exit hole (see two photos below) in the bark.  The exit hole is 1/8" in diamter and can have any orientation in regards to the "flat side".  There are other beetles and insects that normally will visit ashes so focus on the characteristic signs of EAB.  While the adults can't fly very far, the spread of EAB thus far has been quite methodical although odd populations have sprung up here and there presumably as a result of firewood movement.  EAB is easily transported long distances in infested firewood.  The bottom photo shows the logo on one of my T-shirts which says it all.  Transporting firewood in to state parks, campgrounds, etc. could have a horrible impact on native ashes (700+ million in WI alone) and there have been significant efforts to limit the spread of EAB thru education initiatives.  Early detection efforts have value as they help slow the spread of EAB.  There are currently proactive chemical treatments that are offered to thwart EAB in desireable trees.  I'm not up to speed with all of these new chemicals but there is a wealth of information on the internet and from various Extension sources.  Do some more research on this topic as denial wont change the fact that at least for us in this area, EAB is here and is just in the infancy of infestation. 

Today was a relatively quiet day around the gardens.  Pat was out pruning and I saw Maury early with some new paint that we needed.  Del, Dr. Gredler and Urban were all in the Horticulture Center working on various painting or pre-painting projects.  I continue to look ahead to 2013 although I have some 2012 work to finish (including this EAB pamphlet).  Our pamphlet will also stress the importance of "ash alternatives" in the landscape.  I'll sink my teeth in to seed ordering next week.

No comments: