Need Advice on Giant Elm Tree

[Woodman]

My old collage professor had me out to his house today to look at his elm trees. He has two beside his driveway, a big one and a massive. I need advice on if the big one has Dutch Elm Disease, and if so what I should do to protect the massive one. I'm in Northwestern Pennsylvania.

The big one barely has any leaves left. The power company made a heading cut about a foot in diameter last year for no good reason and would have been an easy access point for the beetles. Theres what looks to me like brown streaking under the bark. But I'm not 100% its DED just because I haven't seen that disease much in my career and I expected the leaves to turn yellow before falling off, and the home owner didn't remember ever seeing yellow leaves, and I didn't see any either, just green and brown leaves and bare branches.

The massive one is 30 feet from the other dying elm. At first glance it looks healthy but a close examination of the tips suggest that theres some tip dieback. I'm concerned thats an early symptom of DED. When I have my lift there to remove the other tree I was planning on going to examine, and cut some of the tips to look for streaking. I believe the correct protocols are to cut any tips with streaking back to 10' below any visible streaking and make a root trench before removing the mostly dead tree. How deep and how long and how far from the infected tree should the trench be? I was thinking I would use my RX100X stump cutting to cut a trench as deep as I could (about 18") in the middle of the two trees for about 30 feet. Do you guys think that would work? And can anyone advise me on if I should be considering using a fungicide products and if so which one? It would be shame to lose that big old tree. I've got my BCMA but I don't have a pesticide application license. I would go and get an application license if I needed to though.

I've attach some photos. Thanks in advance for your help!
Ben

Smaller elm thats mostly dead beside giant elm:


Streaking photo from smaller elm:


Foliage from smaller elm:



Giant elm:

Lower foliage from giant elm:

Tip dieback from giant elm:

 

[Woodman]

Also, curious what you all would consider a fair price for the trenching I'm describing. I've haven't done that service for a client before.

 

[Shadowscape]

I'm not a chemical guy so I can't help in that area, but I have taken down hundreds of elms that size with DED, and it sure looks like DED to me by the leaves you are showing. The holes in them are throwing me however. Are any of the twig ends curling into a hook shape? The dark streaks underneath the bark is also a classic symptom of DED. There may be other thing going with some type of larva or insect damage.

 

[oceans]

I’m not about to play tree MD from afar, but…

Do some research on EPN (Elm Phloem Necrosis) as well.

Also, check out the life cycle of the Elm Twig Borer. You may find evidence of its presence. Pretty sure pheromones released through cuts of live growth will actually attract the insects. We always wait for dormancy to prune any live growth on Elms.

DED can enter a tree a couple ways…root graft or twig borer vector in the crown. The way the symptoms appear is a good indicator of how a pathogen has entered.

I’m not thinking that trenching would be a good plan during active growth.

Fungicide treatments can be effective for DED but EPN is entirely different. I have seen significant efforts to treat several large Elms fail.

Good luck!

 

[Shadowscape]

Had to research that myself. Looks like a reasonable candidate as well with similar symptoms, and it is in your area.
Bummer is there doesn't seem to be a cure for it.

 

[oldoakman]

I am with Oceans, Phloem necrosis has taken most of the old Elm's on Penn State main campus over the past 20 years or so. Get good samples and send them to the Plant Disease Clinic at PSU for positive ID. DED is still around though as well but I believe the PN vector is a leaf beetle which would explain the leaf issue.

 

[Tom Dunlap]

Nothing that I see in the pics says DED

 

[Woodman]

Thanks for your input everyone. I collected some samples to send to PSU today, we'll see what they have to say.

 

[ATH]

Elm Phloem Necrosis is also known as Elm Yellows... DED usually goes green to brown while Elm Phloem Necrosis would tend to go yellow first.

Elm Yellows also has a wintermint-ish smell.

Let us know what PSU says.

Did electric company prune during growing season last year? If so and it comes back as DED, I'd encourage the owner to have them do the removal and talk about replacement cost ...and treating the other with Arbortect. Best practice would be to NOT prune elm during growing season. If they must be pruned, immediately treat all wounds to mask volatiles that attract elm bark beetles.

An 18" trench will do nothing....depending on soil type you need to be 3-6' deep.

 

[Woodman]

PSU just got back to me. The one elm tested positive for Dutch Elm Disease (Ophiostoma novo-ulmi), but they didn't detect it yet in the giant elm. So I need to cut down infected one asap. But first I need to dig a trench between the two. I suspect the giant elm has been infected, it's just earlier enough that it wasn't detected. So I think I should treat it with a fungicide. Can anyone suggest a product to treat it with? Also, looking for suggestions for the easiest way to dig a 3-6' deep trench. Thanks for your help everyone.

 

[ATH]

Vibratory plow is the ideal way to do it.

Trencher will do it...just a much bigger mess.

I've done it with air excavation (Airknife) in sandy soil. The roots were cut by hand or chainsaw. There were too many utilities to use anything mechanized on that property. That is slow moving.

As for treating: Arbotect 20-S as a macro-injection. Use the high rate. This is the correct time of year to treat.

 

[Woodman]

Is the vibratory plow an attachment or a separate machine? I'm having trouble finding anything that goes even 3' deep.

 

[Shadowscape]

Is the vibratory plow an attachment or a separate machine? I'm having trouble finding anything that goes even 3' deep.

About the only companies that will have a vibrating plow that goes to the depths you want are the ones who lay high voltage (230KV) power lines, and they don't do much of that because of the cost involved. That is why most high voltage lines are run overhead. The telephone and power companies who lay residential and low voltage lines (under 96KV) lines don't need to go more than two to three feet down, but the high voltage lines need to be a lot deeper.
I would check with the major power distribution companies in your area and see if they can put you in contact with who has such equipment, because when they need it, they even hire it out. The machines that plow that deep are super expensive, and I doubt you will find anyone renting such equipment. There are a lot of 2-3' vibrating plows out there for rent, but to the depth you are looking for, I doubt you will find one.
It is cheaper to bury high voltage in a shallow trench encased in steel conduit than to try and plow a continuous groove 6-7' deep. Doesn't work out very well most of the time.

 

[ATH]

They were using some of the bigger machines to bury fiber optic cable here a year or two ago. There were 2 sitting along the road for months waiting while they did some preliminary work. I was helping a client with oak wilt so stopped to ask if they wanted to run a machine up cut trenches that. Not sure the translation made it through... Instead the nice one god clipped when someone took the corner too tight with a big truck.

So to the question:
Yes, there are purpose made machines. I know one of the local park district had been renting one for oak wilt trenching. I think they were spending $5-6K per week. They also had a customer blade built to get a full 6' that had a hook on the end. I do know there were having trouble finding one last year...asked if I'd buy one and contract the work. I just couldn't see that being my next $100,000 spent.

There are also vibratory plow attachments for a dozer (one of the plows they had sitting along the road here was a dozer) or skidder. I don't think most skid steers have the HP and/or mass to pull one with enough depth.

 

[Reach]

They were using some of the bigger machines to bury fiber optic cable here a year or two ago. There were 2 sitting along the road for months waiting while they did some preliminary work. I was helping a client with oak wilt so stopped to ask if they wanted to run a machine up cut trenches that. Not sure the translation made it through... Instead the nice one god clipped when someone took the corner too tight with a big truck.

So to the question:
Yes, there are purpose made machines. I know one of the local park district had been renting one for oak wilt trenching. I think they were spending $5-6K per week. They also had a customer blade built to get a full 6' that had a hook on the end. I do know there were having trouble finding one last year...asked if I'd buy one and contract the work. I just couldn't see that being my next $100,000 spent.

There are also vibratory plow attachments for a dozer (one of the plows they had sitting along the road here was a dozer) or skidder. I don't think most skid steers have the HP and/or mass to pull one with enough depth.

That’s a very expensive machine to use, just to do a bit of trenching. You might be able to find a large electrical contractor that would rent one out to you, or more likely send an operator to do your cutting.

The more economical option would be to rent a large chain trencher, or a chain trencher attachment for a big skid steer. I have done some trenching with a skid steer, it’s a little slow going, but it does work pretty well as long as you don’t live in a rock quarry.

 

[ATH]

I don't disagree... Vibratory plow is great if you have several properties lined up. You can hardly tell where it's been. I just said that is the ideal. Regular trencher is certainly more available.

Heck, even a backhoe will work...even slower and more messy, but may be easiest to find.