Unusual disease outbreak in ash trees

Lots of local news coverage on the impending invasion of the emerald ash borer has many owners of ash trees alert for any unusual symptoms. So I was not surprised by the number of recent calls I’ve been getting about blighted ash leaves. Leaf drop in mid May is a common phenomenon, especially when it’s rainy when the leaves are just expanding. The culprit usually is a leaf disease called ash anthracnose which, while the symptoms can be alarming, it’s generally temporary and pretty harmless. But when I got two different calls yesterday-on Memorial Day- in which both clients used the word “orange’ in describing the symptoms- I realized something unusual was going on. Here’s what I found at a client’s property in Pottstown:


ash rust2

ash rust

The disease is ash rust, Puccinia sparganioides. Spores from the disease on ash cannot infect another ash. They can only infect an alternate host, which is cordgrass which grows in salt marshes. Ash rust is common near salt marshes. But we are quite a distance from the nearest cordgrass marsh, making this a rather unusual event.

Emerald Ash Borer Scouting

The way this client found me is a little bit strange.  He found my website by googling “bacterial leaf scorch” (I have articles posted about my experiences with BLS).  That’s what another “arborist” told him was wrong with his ash tree.  And that the disease would kill the tree, so he should remove it.  Well, ash trees have a few problems around here of late, but bacterial leaf scorch isn’t one of them.  Anyway, the tree didn’t look good and we talked about the true ash ailments – ash anthracnose (which the tree did have) and emerald ash borer (which hasn’t been found close to here yet).  In the end, he agreed we should inspect the tree for EAB, just to be sure.

Today, Ricky and Dave climbed the tree, and the one next to it, and checked it thoroughly.  Good news – negative for EAB.

The ailing ash

The ailing ash

Holes in leaves

Holes in leaves: from the ground you can’t see them in detail, can’t tell if it’s insect feeding damage; close up it doesn’t look like it. More likely caused by damage to buds from our late frost

We look for any clue - here you can see the wood pile contains ash firewood

We look for any clue – here you can see the wood pile contains ash firewood

hackberry emporer butterfly

While we were getting started, this hackberry emperor butterfly came by and took a liking to the minerals on Dave’s hardhat strap.  (Click the image to see a nice big version!)

Dave and Ricky

Dave and Ricky each went up a tree

a good, closeup inspection of the crown

…and did a good, closeup inspection of the crown.

If you have ash trees and are concerned about emerald ash borer now that it has been discovered in Bucks County, right now is the best time to have them checked.  This is the peak time for emergence of the adult insect.

Emerald ash borer update

Have you noticed all those purple sticky traps?

Emerald ash borer sticky trap

Emerald ash borer sticky trap

The PA Department of Agriculture has hung them in ash trees all over eastern PA this summer.  My guess is we’re going to find out about a considerable range increase for this terribly destructive insect.  Already this year, 2 new counties have been added to the list, Huntingdon and Wyoming.  IT IS NOW IN THE EASTERN PART OF PA, having been detected just north of Wilkes-Barre.

Things you need to know: – Adults can fly on their own approx. 1/2 mile.  So the pest isn’t moving very fast on its own.

– It gets help in colonizing territory from people moving infested firewood.

– If emerald ash borer gets close to your area, your landscape trees can be treated by soil injections.  Bigger trees can only, so far, be successfully treated by trunk injection of insecticides.  Treatments need to be done annually to be effective.

– Experts do not suggest treating trees unless an infestation has been detected within 15 miles.  To treat before the threat is there is a waste of money.  And trunk injection is an invasive procedure.  Don’t injure the tree with it until you need to.  And don’t believe anyone who tells you that their trunk injection method causes no injury to the tree.

– If your trees are monitored by a competent arborist, you are not likely to be caught by surprise by emerald ash borer.  If it    shows up, you will have time to control it if you choose to.

NEW information: A new chemical is available that is highly effective and lasts more than one season.  Hopefully it will be  legally registered for emerald ash borer control in Pennsylvania soon.  And hopefully the price will come down (it’s very expensive).

MORE NEW information: A new monitoring tool may soon become available.  Recent research on developing a sex attractant (pheromone) has been promising.  The purple monitoring traps now use two aromatic tree oils as attractant.

Still more new information: Research has also uncovered promising indications of natural biological control of emerald ash borer.
We in southeast PA are lucky to have the benefit of a decade of other’s experience and research before having to face the emerald ash borer.

Another “Emerald Ash Borer” Scare

I was called to the clients’ home because her beloved huge white ash was not looking healthy- lots of dead wood- and had been receiving a hammering from wood peckers.  When I checked the tree, besides the woodpecker holes, I observed many exit holes in the bark that had been produced by boring insects.  Some were the typical oval shape of the ash-lilac borer, but some had that dreaded “D” shape that could possibly indicate EMERALD ASH BORER.

Sure looks similar to E.A.B!

I looked closer, picking away at some of the dead bark and poking into the borer holes.  Eventually I found, to my relief (and the tree owner, Anna’s!), the wing cover of an adult ash- lilac borer in one of the “D” shaped holes.  False Alarm!! Not EAB!


The client REALLY wanted to save the tree, but I didn’t want to waster her money on an expensive pruning job if it were doomed anyway because of Emerald Ash Borer.  So my men climbed the tree and checked the dead branches, also, for signs of E.A.B. infestation.  All clear.  We went ahead with the pruning.  The tree is not in the greatest health but it’s now a lot safer without all those dead branches above the driveway and patio.  And it looks nicer too, don’t you think?




Emerald Ash Borer found in Kentucky

Last week the office of the State Entomologist in Kentucky confirmed reports of this devastating invasive insect in Shelby and Jessamine Counties.

Emerald ash borer was introduced to the US from China by way of imported wood products.  Since its discovery in 2002 it has spread rapidly, and will probably continue to do so.

Emerald ash borer was detected in Pennsylvania in the westernmost part of the state in 2007, and hasn’t been found farther east until just this past February (2009) when it showed up in Mifflin County (in the middle of PA) so learn what to look for if you have ash trees – apparently there is no stopping it from eventually reaching us.  More info at http://ento.psu.edu/extension/trees-shrubs/emerald-ash-borer.


The beautiful weather of this weekend will surely kick off our spring busy season.  I can’t wait, it’s been a long winter!

The Virginia bluebells in front of my office window are now in full bloom.

The Virginia bluebells in front of my office window are now in full bloom.

Note the spring beauties and a few dandelion in the lawn in foreground :mine’s not the typical suburban sprayed sterile lawn.

Today I saw the first blossom in my strawberry patch.  Spring’s definitely here.

Also today, in my driveway, I spotted this beautiful emerald green beetle.

THIS IS NOT THE DREADED EMERALD ASH BORER!  (the adult EAB does not emerge for another two months).  And, thankfully, they still have not been found here in Montgomery County, although they are in western PA.

The webs of eastern tent caterpillar are starting to become noticeable on the native cherries in the woods, as well as on the crabapple in my nursery.

I get a lot of calls about ETC, (with people often confusing it with other more destructive pests such as gypsy moth).  Don’t let them worry you – they are not going to invade like some of the introduced pests and populations are kept in check by natural enemies such as assassin bugs, parasites and birds. (it’s a favorite food of the Baltimore oriole)  I’m not going to spray the ones in my nursery, I’ll probably just destroy the nests before they eat a lot of leaves.


If I’d noticed this egg mass – the things that look like a swollen area on the twig – over the winter, I could have just pulled it off then and prevented its hatch.

Exciting things are happening outdoors every day, and at an especially fast pace at this time of year.  I’m going to try to keep you updated with regular posts here on this site, hopefully with some links to more information on some of the topics.