Snow damaged trees

The snow is melting and the tree branches are springing back up. Tomorrow we’ll mostly be cleaning up the debris from the broken trees. After that , we can inspect the damaged trees and make the right pruning cuts where branches are broken.

I’ll be able to fix a lot of the bent arbs etc by bending them and reducing co-dominants. And I can talk to you about phasing in a new tree to replace that beat-up Bradford pear.

More stuff on how to deal with snow damaged trees at Snow Damaged Trees

European Hornets (Followup)

Renee wanted me to help her get rid of the hornets. So I had to decide how to go about it. The most effective way to control European hornets would be to destroy their nest and colony. But we have no idea where the nest is – probably not even on her property. If we went to spray the hornets we see on the trees with an ordinary contact insecticide we’d just kill those individuals present at the time.

So I opted to coat the bark of the trees with a material called dinotefuran. It’s a neonicotinoid, like Merit, with which you may be familiar. But it’s much more soluble, so when applied to the bark of a tree it can be absorbed, and then conducted through the tree’s phloem. And the phloem of the birch branches is where these hornets are feeding.

I made a visit to Renee’s today to check the results. There were no longer any hornets on the tree. But there were MANY on the ground, all either dead or dying.

European hornets

European hornet

So I think we made a good choice. Though we did have to intervene with a pesticide, the one we used – dinotefuran – is unlikely to cause harm other than to the target pest. It is extremely low in toxicity to humans. And with the trunk application method, the material all goes where we want it – in the tree. The only exposure is to whatever eats the tree. And, being so highly soluble, it dies not last very long (like Merit does). So it won’t be affecting beneficial insects like bees next year, after its job is done.

Post Script: I found a really good article since I had this experience. It’s by Frank Santamair, in the Journal of Arboriculture from 1984.

European hornets

European hornetsThese are European hornets.
European hornets
I never really thought of them as tree pests before. When I see them on trees, usually they’re feeding on sugar that’s been excreted by aphids or scale insects, or on the alcoholic wetwood flux  oozing from a mulberry or a dying elm. But I may be changing my mind a little bit , after what I saw today. Renee, from Audubon, showed me these insects, which she had attempted to identify by searching on the internet. She had noticed them before, but could no longer tolerate them because her son was stung by one of them, and it was a pretty bad experience.
They were congregating on two of her river birches. I waved my hand a few inches from a group of them and they didn’t react at all. They really aren’t very aggressive, normally.The branch of the birch tree was stained with sooty mold, indicating sugar, such as from an insect injury.
European hornets
On closer inspection, I could see that the hornets were not feeding on the sugar; they were actually causing the injury that produced it. These hornets had chewed away the bark all the way around one branch, killing it!

I know they need cellulose to make the paper to construct their nests, but this is the first time I’ve seen this type of damage. You learn something new everyday!  One more interesting observation: while I was trying to get a photograph, I watched a baldfaced hornet approach a group of the European hornets.  The Europeans reacted immediately and chased it away. After that, their behavior was completely changed- they were very aggressive toward ME and would no longer let me get close!
(check back later to see what we did about it)

Diagnosis: Probably herbicide injury (second time this week) This time: IMPRELIS!

Mrs. B from Royersford called yesterday concerned about her douglas fir trees. She told me one was turning brown at the top, and also the white spruces didn’t look so good. She reminded me that I had sprayed them to control a disease problem a few years ago and was wondering if maybe they had the same problem again or maybe bagworms or something. As soon as I saw them I knew that it was neither of those problems. I explained to her that similar symptoms on different species most likely indicated an abiotic problem, not a disease or a pest, which are usually host- specific. The way the young growth of the doug firs was wilted and killed made me think of herbicide poisoning. In fact, it looked exactly like the symptoms of poisoning from Imprelis, Dupont’s new turf weedkiller.

Douglas fir - Imprelis injury

Douglas fir – Imprelis injury

White spruce - Imprelis injury

White spruce – Imprelis injury

Douglas fir - Imprelis injury

Douglas fir – Imprelis injury

 

Douglas fir - Imprelis injury

Douglas fir – Imprelis injury

The story of Imprelis is a really interesting one, and it is soon going to be big news. Heres the condensed version. Last year Dupont introduced this completely new product with great expectations for its potential. It is extremely low in toxicity to humans and at the same time very effective at controlling broadleaf weeds. So it was immediately popular. But this spring, all over the country cases of dying evergreen trees were being reported, mostly white pines and Norway spruce. And it wasn’t long before it became evident that there was a connection between these injured trees and Imprelis herbicide . The thing that these mysterious cases all had in common was the turf around them had been treated with Imprelis. Dupont initially did not acknowledge responsibility, but just last week they pulled Imprelis from the market. I’ll try to get some of the news articles and Dupont’s statements up here soon.

Anyway back to Mrs. B’s trees. I told her my suspicion. She said “but I have a lawn company that just uses organic treatments.” I responded; “maybe so, but there are NO weeds in your lawn. There is no organic weed control that is truly that effective.” I suggested she call the lawn company and ask them what chemicals had been applied. And told her to google “Imprelis.”

Then I left to go visit another client. Before I even got to Limerick, Mrs. B called me to tell me what happened. She had called the lawn company as soon as I left, and they were completely upfront with her. They acknowledged that they had applied Imprelis on June 13. And they now know there is a big problem., and want her continued feedback.

Do you note the irony here? A person thinks they’re being environmentally responsible by choosing the supposedly “organic” option, and this is what happens to them. Drag.

Diagnosis: Probably herbicide injury

On Monday I checked on an ash tree for a client in East Greenville.  She said the leaves appeared to be wilting.

The ash tree

The ash tree

Well, they didn’t really look wilted to me, but they were distorted and curled.

The curled ash leaves

The curled ash leaves

The curled ash leavesThe curled ash leaves
I unrolled some of them to check for pests; none were there.  No aphids, no silk from any caterpillars.  There was an outdoor fireplace nearby.  But if that were the cause, I would expect the symptoms to be the worst closest to where the fire would have been.

 

 

 

 

 

Next to the ash is a young saucer magnolia.  Last year I treated it for a bad magnolia scale infestation; so while I was there, I examined it.  The scale was gone, but it too had a lot of distorted leaves.  And, like the ash, no pests, no aphids.

The magnolia

The magnolia

When trees of different species have the same symptoms, it’s probably abiotic – not a disease or a pest.  Pests and diseases are usually host-specific.
Near the ash and magnolia is a Kousa dogwood.  Same thing – distorted leaves.  And the type of distortion that is generally seen with certain herbicide poisoning.  That is, elongated parallel veins and interveinal chlerosis.

Kousa dogwood

Kousa dogwood

Kousa dogwood leaves

Kousa dogwood leaves

There is another ash a few hundred feet away also at the rear of the backyard.  It has the same symptoms, only even more pronounced.

The other ash

The other ash

Well, all the symptoms are consistent with the effect of herbicides, but the client’s lawn is definitely not weed free.  If that is the cause, the likely reason is spray drift from the hay field adjacent to the yard.  The field looks very clean, hardly any weeds.

The hay field

The hay field

So that is my theory – all the trees were damaged by herbicide drift from the application to the hay field.  And that is what I told the client.  And she confirmed that the field was recently sprayed.  She will ask the farmer to be more careful in the future.

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.