woolly hemlock adelgid?

macrocarpa

macrocarpa

Branched out member
Location
Midwest
Almost every untreated hemlock tree I inspect has adelgids in north east TN. I have read all kinds of literature about the most effective forms of treatment. Micro inject, soil inject, foliar sprays, organics etc. and there seems to be many conflicting studies/opinions on this topic.

I would appreciate any experienced advise on treating hemlocks, pros and cons of mico & soil injections, organics etc. and any advise about treatment pricing.

As for damaging a tree when micro injecting, is it the toxicity of the chemical that is the major concern going straght into the xylem or the actual wounds from drilling?
Because yellow bellied sap suckers drill all over trees and studies have shown little damage to tree health?

I just want to find the best methods for saving the hemlocks while also being environmentally conscientious.
 
I think the concern with microinjections is the location, at or near the root flare. Cut stumps from treated trees have shown some more advanced decay from the drill holes.

As to soil injections, I have used merit combined with a diluted fertilizer in the past, and the following year we had the worst case of spider mite I have ever seen. I believe there was a connection, but I don't have empirical data to back that up. I no longer recommend the use of merit based on it's negative effects on bees and to some extent earthworms. Vigorous specimens seem to be much more resilient, so it seems to me that tree health plays a substantial role as well.

I'm hoping to get some better info from other buzzers, too.

-Tom
 
Wow, I can't believe how timely this post is. I was just going to open a new thread on this topic myself.

Tom, could you expand on the negative effects of Merit on bees? That is sort of a big concern, bee population.

I have to come up with a good treatment reccomendation for several stands of Hemlock at our Presidents residence. They were treated with Merit by one of the local Commercial applicators last year, but it was totally inneffective. After looking at the site, I feel that there was no way that the company that did the work could have made an accurate judgement on application rate.

The number of trees involved and the price they charged would not have allowed them time to get DBH measurements, and most of the beds are covered with English Ivy. It would seem logical to me that the competition with the Ivy would make it difficult at best to come up with an accurate dosage.

Environmental impact is also a very big issue for us in this case.
 
Thanks Tom,

I have also noticed that the spider mites sometimes move in after hemlock treatments.

Say a homeowner has 10 large hemlocks and has to treat for both adelgids and spider mites every several years, would it have been a better choice to let the trees die, remove them, grind stumps, replant and wait years to regain a mature landscape? Or put confidence into treatments? Both are very costly.

As for soil injection vs micro injection, we have a lot of rocky soil here and in the situation I looked at this morning, only half of the drip line is accesible because the other half is the neighbors property and there is a large garage right under the trees (in the root zone). So here is a situation when I would feel micro-injection would be the best route to take?

I welcome any advise and any organic treatment success stories.
 
TN, just Google 'Imidacloprid and Bees' and 'Imidacloprid and earthworms,' and you will find alot of info and articles on the subject. A professional dealer of the stuff actually said to me "Be careful with this stuff... If honeybees even fly NEAR it, they can die." That was the guy selling it.

Macro, I think microinjection is better anyway, based on the negative effects of Imidacloprid when it is released into the environment. At least this way there's little to no off-target effect. At least on your part.

The client with the spider mite problem stopped treating about four years ago... We fertilized, and have treated with compost since then, and she is adelgid-free. So the initial treatment killed them, and the tree vigor has kept them away. I have seen many healthy trees in well irrigated but well drained sites, with only partial sun, and not alot of underplanting. So those could be some clues.

As far as removal/replanting, I usually suggest that if the trees are either too far gone or if they are not overly valuable.

-Tom
 
On the problem of injection portals and necrotic xylem - the agents injected, whether they're hydrocarbon based or nutritional ammendments, you have to buffer them to the matching pH of the tree.

Tom's suggestion of natural ammendments works well here, alongside soap treatments to the stems and canopy.
 
It's been a few years since I've done HWA treatments and I haven't keep up to date so the following may not be too current.

I did 95% of my treatments with Merit soil injections and got great results in a high %age of cases. At that time the recommendation was to do the soil injections within 2-3 feet of the trunk.

If that is still the recommendation, there shouldn't be a problem with your limited area Macro or with the Ivy TNT mentioned.

TNT, if the treatment was ineffective could it have been the timing or lack of soil moisture? On another note, I might consider removing the Ivy and replacing with mulch to create a more favorable environment for the Hemlocks. Think of a mature Hemlock stand in the woods, not much growing under them.

As far as the spider mite thing, I've heard it before and it makes sense if we are talking about foliar applications.I have seen hundreds of trees that were heavily infested with spider mites after foliar treatments of a broad spectrum material. Then the predators are gone the bad mite flourish. I don't see how the merit could be the cause with injection applications. Same for the Bee thing. Worms, well probably, I think it would be limited to a small area when the injections are within 2-3 feet of the trunk.

Macro, as far as the micro injections, the chemicals make it worse.

As Tomthetreeman mentions, Health and site are major factors.

Of course I may not know anything about this at all.
smile.gif
 
TNT, I have worked on a lot of hemlocks in JC (pruning) that where soil injected and I still see adelgids and fading foliage color. One theory may be that we were/are in a serious drought for the last 2 years and the more I research, lack of soil moisture combined with tree stress may be the reason the imidacloprid is not being up-taken. Along with what you said about competing ground ivy etc. This fact combined with what Tom has brought to my attention about bees and earthworms, amphibeans and fishes, makes me even more inclined to push micro injections even though it may be more damaging to the tree. They say that studies show longer imicide residual effects then originally predicted. So if a customer were to get control of the insect and then use cultural means of prevention by keeping the trees healthy for 3-5 years before retreatment is necessary, that would be ideal but maybe not realistic?

Still would like to hear of organic HWA treatment success stories.
 
Macro, yes I agree. The issue that I am struggling with at Shelbridge is that there is going to be a huge amount of labor involved with clearing all of the ivy, restoring the mulch, and getting irrigation to the trees. The property is way overgrown and there is only two full time staff over there.

I'm sure that our drought conditions are a major factor in the uptake.

Right now my reccommendation is to select several of the healthiest to try to save, and remove most of the others. The hemlocks on that property are causing shade issues with the other plants on site, and the Stantons do not want the ivy removed (?). I don't think that the state can justify the cost and labor involved with saving them all. I have too much work on campus to be able to send one of my crews over there to do the job and then follow up with the after care.

There are several trees on campus that i was able to effectively treat with a soil drench last year. The ability to keep them watered, and condition at time of treatment are deffinately key factors in how well it has worked.

So I'm sort of stuck. They don't want to do what I have reccommended, and we cant do what they think they would like. I will address this again next week and hopefully come up with a reasonable compromise.

An organic solution would be ideal.
 
I have to correct my earlier post, as it is becoming apparent that I am losing my memory LOL.

The year before I did the soil drench, I had a friend of mine with a spray rig hit the tree with a foliar application of Imidacloprid. It was the SAME YEAR that we had the spider mite outbreak. Because of that we switched to the soil treatment the following year, and after that we went to the compost treatment (combined with deep watering) for several reasons, including my changing views about the chemical.

Eric E is right, the spider mite problem is related to foliar application. Thanks for jarring my memory!

I like the thought process of eliminating the pest the hard way and then going preventative... Makes sense to me.

-Tom
 
Merit has been proven effective. I've used it for years on HWA (mostly soil injection). Proper soil moisture is critical. Results can take up to 18 months to be seen, but residual control is good. As for leaching and unintended targets (bees and worms), merit is very immobile in soil, and does not have a great propensity for harming aquatic organisms (unless the directions are not followed - use trunk injection within 25' of water). Only worms that come in contact with soil directly around the trunk should be impacted. I can see foliar sprays harming bees, but the only way a bee will be affected by soil injection is by ingesting pollen from a hemlock - I don't know - do bees even eat hemlock pollen?

I've switched to Safari for HWA. Much quicker uptake, soil moisture is not critical, and residual is good.
 
mp, the impression I got was that if bees even got NEAR it they could die. I think the salesman's words were 'if they fly close to it.' I am assuming he is referring to vapors in the work/soil area or airborne powder while mixing. If you are doing a soil injection or drench, well, I'm guessing that ALL of the earthworms in the treated zone would be affected. No worms=no soil aeration. Based on these things, I think that the trunk injection is the way to go, as long as it isn't prolonged and repetetive.

-Tom
 
Merit works on HWA, how about the tougher, more damaging pest......Armored Scale? Such as the Elongate Hemlock Scale. Tough cookie to crack, especially since they are on the undersides of the leaves.
 
Does anyone use the horticultural oil approach anymore, or no? We spend a good deal of time in spring doing dormant oil sprays up here in MA where I'm employed.
 
[ QUOTE ]
Does anyone use the horticultural oil approach anymore, or no? We spend a good deal of time in spring doing dormant oil sprays up here in MA where I'm employed.

[/ QUOTE ]

We do as well.
 
We got so carried away with the discussion of Merit treatments, we never even broached the topic of Hort oil OR Insecticidal soap! Methinks this thread liveth again!

-Tom
 
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