Maryland's effort to restore hemlock forests

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Maryland's effort to restore hemlock forests

Post by PAwildernessadvocate » Thu May 05, 2016 9:46 pm ... story.html

The Baltimore Sun
Tuesday, May 3, 2016

Patapsco Valley is proving ground for Maryland's effort to restore hemlock forests

By Scott Dance

Decades ago, several hundred hemlock trees stood in a section of Patapsco Valley State Park around Cascade Falls along the Patapsco River near Elkridge. Today they barely number 100.

Similar losses have hit forests from Georgia to Maine in recent decades as an invasive insect has feasted on hemlock sap. The thinning numbers are a significant loss for the ecosystem because the towering evergreens provide habitat for nearly 1,000 types of creatures — hundreds more than other trees do — from birds to microscopic invertebrates.

But an effort to restore hemlock groves in Maryland is under way. More than 200 hemlock seedlings will be planted in the Patapsco Valley this month, along with another 280 in Western Maryland. Hundreds more will come over the next several years through a serendipitous partnership with Pennsylvania.
"There is no better way to save biodiversity than by preserving habitat, and no better habitat, species for species, than wilderness." --Edward O. Wilson


Re: Maryland's effort to restore hemlock forests

Post by Joe » Fri May 06, 2016 6:53 am

Nice token effort, but planting a few hundred seedlings isn't going to "restore hemlock groves in Maryland". The odds are that those seedlings won't even survive against faster growing species unless they are watched very carefully and the other trees are repressed. Then, what will keep them from being attacked again? I have some doubts about, "the towering evergreens provide habitat for nearly 1,000 types of creatures — hundreds more than other trees do". Hemlock provides a better habitat than any other species? Maybe they should plant Norway Spruce instead.

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Re: Maryland's effort to restore hemlock forests

Post by Erik Danielsen » Fri May 06, 2016 9:30 am

Weird narrative about Hemlock being uniquely ultra-valuable to wildlife compared to other species- always peeves me to read things like that. Do we really have to set things up with so much exaggeration to convey the fact that these trees are very important to the ecosystems present and that their loss is damaging?

Planting trees in a forest for ecosystem reasons is always questionable. The question first has to be asked- why are the trees they're replacing gone, or if they're not entirely gone, why are they not reproducing successfully on their own? Forests don't need replanting- people just get warm fuzzies from the idea that they've done it. It's reminiscent of the "million trees" initiative here in NYC. Just focus on quantity of trees, not the actual ecosystems context. I run into "restoration plantings" from the million trees initiative all the time. Picture a bunch of dead sweetgum saplings planted in an acidic sand barrens with happy little tags from the nursery. Sure, they're "native," unlike the Pawlonias that had shaded out natural oak barrens community, but that doesn't mean they're suitable...

I have some very well-meaning friends who maintain a property of theirs in WNY as a nature preserve. They're very sweet people but have no idea what they're doing when it comes to plant communities. On arbor day they posted photos of a bunch of happy people planting hemlocks in the forested portion of their preserve. The kicker is that their forest is already mainly hemlock, the adelgid hasn't hit yet, and the only obstacle to their reproduction there presently is heavy deer browse. Resources should have gone into proper exclosures, not planting trees that would grow naturally on their own, from nursery stock of unknown site suitability.

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Re: Maryland's effort to restore hemlock forests

Post by gnmcmartin » Sat May 07, 2016 1:29 pm

NTS folks:

Maryland is making only a very mall token effort to preserve/save the hemlock forests still surviving in the State. My timberland has as fine a growth of hemlock, I imagine, in private hands in the entire state, and I have been offered no assistance, and no advice on what I can do to preserve these wonderful trees. So they are planting a few seedlings somewhere!! Disgusting!


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Re: Maryland's effort to restore hemlock forests

Post by Don » Sat May 07, 2016 4:23 pm

I think you need only ask Will Blozan to here about the latest in hemlock wooly adelgid treatment technologies...he's current!
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Re: Maryland's effort to restore hemlock forests

Post by gnmcmartin » Sat May 07, 2016 8:01 pm


I have been in communication with everyone I can find who has any knowledge or interest in the adelgid situation, including Will, and still have no idea about what I can, or should do. I have about 300 acres, well over 200 of which have very substantial hemlock populations. Chemical treatment on a scale that would do much to preserve so many trees over such a wide area seems to be very problematic, both in terms of labor, and/or cost. And, can I treat once, at a cost of many, many thousands of dollars, just to have to treat again in 7 years? And if I decide to treat, I have found no two people who have the same advice about how best to proceed, even if it were practical for me to do so. I could go into detail about the various approaches, and the plusses and minuses of each.

In addition, a good portion of my most beautiful hemlock trees are in, or adjacent to wetlands, and chemical treatments are illegal, except, perhaps, by direct injection.

I have been given cost share assistance, and tax relief from MD for practicing good forestry, but no help, or even advice, about how to preserve such a magnificent hemlock forest. Well, about 7 or 8 years ago, a "memo" was distributed to MD forest owners suggesting a harvest of all hemlocks. I would think, at a minimum, some memo updating the research that was underway in MD could be distributed. What would that cost the State??

The current question, to which I have not yet been able to get an answer to, is whether nor not any of the predator beetles that have been released, and which reports say had developed adelgid eating populations, survived the unusually cold winters of two or three years ago in the mountains of MD and WVA. Those winters, for the time being wiped out the adelgids--I have not been able to find a single one since. If the adelgids are now gone from the areas where the cold was most severe, of course, the beetles that fed exclusively on them must be gone also. But, what about the beetles of a kind that had alternate prey? I could make renewed attempts to call and ferret out some information, but no one in Maryland, when I last checked in the fall, had any information, which seems strange. My contact at the Department of Agriculture in Elkins has moved on, and last time I called, he had not been replaced, and I could get no information. Long term, it seems to me, the only hope is this "beetle" biological control approach. Chemical treatments are a temporary fix, and while I could afford one treatment, I can't do two or three. My wife may survive me, and I should preserve some kind of estate.

Will has assured me that, although I can't find any adelgids now, and the trees are recovering, they will be back very quickly. If few, or none of the released beetles survived, then it seems to me that I will just have to let my hemlocks go. But I find it difficult to accept that just yet. If, someone could tell me that there is some reasonable hope that the biological approach could have some success in some reasonable forseeable future, I would suck it up, and do a chemical treatment, regardless of cost. If there are surviving predator beetle populations in my area and at my elevation, that would be of great interest to me. But no one in MD is prepared to tell me, yes, or no. I suppose I should make a renewed attempt to contact the USDA office in Elkins and see if there is any information about their beetle populations in the WVA mountains near my timberland.

In any case, my impression is that the State of MD doesn't care about the issue.

OK, OK, I am just "grousing." Sorry, forgive me. For me the loss of this forest is a bit hard to take.


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Re: Maryland's effort to restore hemlock forests

Post by Will Blozan » Sun May 08, 2016 9:29 am


I have been at the forefront of all things HWA for many years, as you know. I have attended virtually every meeting pertinent to the pest. Here are some summary statements that represent the current reality.

1) Predator beetles have NEVER been found to work on a preservation scale. They are established at least here in NC- but not in levels sufficient for stand retention of eastern hemlock.
2) Predator beetle populations virtually disappear with winter-kill of HWA. They are obligate feeders.
3) Hemlocks by water can be treated via soil injection/drench; it is not illegal and don't know where that idea came from. MD has no exclusions on labeled products that I am aware of.
4) I am currently involved in several projects with a dual approach; chemically treat over-story "mother trees" and concurrently release Laricobius nigrinus in the infested under story. This way. the stand doesn't die and the beetles can begin to establish population levels sufficient for control. At least it's a theory, yet winter kill of HWA would eradicate beetle populations (from lack of food, not cold).
5) Large-scale treatments likely cost less than you think, at least with my team ;)


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Re: Maryland's effort to restore hemlock forests

Post by gnmcmartin » Sun May 08, 2016 11:27 am


I was aware that no successful biological control had yet been achieved, only that populations of some kind of adelgid eating beetle had been established, with some hope of control at some future time. Are you saying that the report I had seen that there was one kind of beetle that could survive on some alternative prey is incorrect? Or, that if there is such a beetle, that there have been no sustaining populations established? If this is true, and that any cold snap will of course eliminate both the adelgids and the beetles (Laricobius nigrinus), and also true that the adelgids can repopulate the area much faster than these beetles, then I see no hope of any kind for biological control in areas like mine where every 20 or 30 years a cold snap will just start the problem/cycle all over again.

In the winter of 2012/2013, the killing cold went like this: We had well below zero in the middle of November--exceptionally early. I think it possible that this cold came at a time when the adelgids were more than usually vulnerable. Over the main part of the winter, we did not have extreme cold, but we had about 20 days with the low temperatures between 15 and 20 below zero. This degre of cold may have stressed the beetles, but I doubt that it killed them, given that those temperatures are not that unusual, and the adelgids had been increasing/spreading for a number of years. Then on or about March 18, we had another very, very unusually timed cold snap--again with temperatures well below zero--again, I am guessing--at a time when the adelgids were more than usually vulnerable. I would not expect this kind of weather to come again for a very, very long time. I have owned my timberland since 1971, and this was the first time anything like these very early, and very late cold snaps happened.

There have been much lower temperatures deep in winter, with a record official low in nearby Oakland MD of minus 40. Maybe that would kill adelgids. The lowest I saw since I have owned the timberland was in January of 1975--I think that was the year--with minus 27 in Oakland, and somewhat colder at my timberland, at close to minus 30 or a bit more. But at that time, there were no adelgids, so I don't know if this level of cold would have killed them.

My point here is that adelgid killing weather in my area is rare, but it will happen occasionally, so any biological control, at least with Laricobius nigrinus, would not seem to have any long lasting effect.

Is Laricobius nigrinus the only species of beetle that offers any hope of control? I have seen a list of several other species being considered as possibilities.

When my forest was under serious attack about 4 years ago, you said you would get back to me about the possibility of you and/or your team being able to come up to MD to offer treatment, but I never heard from you. You are, I know, very busy with this work, so I did not pester you, especially since I am so far away. So far, the best option for me seems to be the imadacloprid tablets, which, to treat my hemlocks to any degree that would preserve at least some of the character of my woods, would cost somewhere between $15 and $20,000, depending on the bulk discount I could negotiate. For me to do soil injection would involve just too much labor carrying all the water through the woods for distances of up to a mile. If I could hire someone to assist me at a reasonable cost, I could treat my hemlocks with the tablets to some effective degree over a 3-year period, based on the best assumptions I can make about my vigor at age 77--as of now (I do get older, and less vigorous every year)--and the ground I could cover in a given day, and the number of days I could be free to do the work each year. I have done careful calculations, but my basic assumptions could be very inaccurate

If there is no hope that Laricobius nigrinus could achieve effective control in a "reasonable" time period, or ever, given the climate of my area, I will just have to watch these woods become quite ugly in their death, and the land enter a transition phase that will take longer than I could possibly live.

As of now, these hemlocks have a reprieve, so I have suspended for now, my study of realistic plans to proceed with treatment.--for how long?? I have no idea.

My idea that there are restrictions on the use of soil injection, and other chemical applications is based on statements like this from the MD DNR:

Soil Injection. A 75WP formulation of imidacloprid (e.g. Merit) applied using a kioritz
injector around the base of infested hemlocks will be the treatment option of choice for
stands of hemlocks at least 50ft away from water. Individual trees or small groups of trees
that are 50ft or more away from streams will be treated using soil injection. Larger stands
may be treated in increments over time using this method as well.

I had personal communications with at least one MD forester telling me that there are restrictions near streams and in wetlands. When the time comes, I will ascertain just what the truth is. I do know that MD has, just this year, increased the restrictions on the use of imadacloprid, but these new restrictions may have nothing to do with any of the HWA control applications. I was told the concern has been for fish, and the new restrictions are because of concern for bees.

But, did you tell me that you often use a different chemical? And might that one not have the restrictions that I have been led to believe are in place in MD? But then another question arises--is the alternate chemical available in a form that is dry, such as the imadacloprid tablets, or would it require the carrying of amounts of water that I would have no hope of accomplishing over my timberland? Or, could I use some of both, depending on the area to be treated, and the existence, or not, of any environmental restrictions.

At this point my confusion and frustration about all this are only increasing, --yes, massively!


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Re: Maryland's effort to restore hemlock forests

Post by gnmcmartin » Wed May 11, 2016 11:10 am

Will and others interested:

I found this site, which gives what seems to me to be a reasonable summary of the HWA control issues, as of 2014: ... 014-05.pdf

I am in the midst of a renewed search effort to learn what I can, and have contacts that are initiated, but not completed. I hope to have more later.

But one issue is now of special interest--the use of Sasajiscymnus tsugae. One article I found, again from the USDA, touted its success in a release in Connecticut. An organization called Save Our Hemlocks is touting its potential, and they are connected to a lab that sells them. But the USDA article I link above says that their use has been phased out in the south. This predator has an alternate food source in an adelgid usually on white pine, so that could help in my situation.

Oh, one interesting thing--I have a friend living near Providence, and he has a hemlock screen that was heavily infested, but about 5 years ago they disappeared, and have not come back, leaving his hemlocks thriving. Could some Sasajiscymnus tsugae have migrated to his place???

Another fact of interest--there are over 20 predators the Pacific NW that feed on adelgids. Ours here are from Japan, but could we be experimenting with a lot more predators, and not rely on just one or two? Maybe we need an "army" with lots of weapons.

Oh, another fact: the hemlocks in the Pacific NW and in Japan, in addition to being helped by the abundant predators, have a natural resistance to HWA. Ours in the east don't, so our problem in more difficult.

Well, this is a confusing issue. It seems everyone I find in print, or talk to, has different ideas. I will continue to try to sort it all out, and decide what I can do, if anything. If I learn anything more that seems important or interesting, I will report back.


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Re: Maryland's effort to restore hemlock forests

Post by gnmcmartin » Sun May 15, 2016 11:30 am

Hemlock lovers:

I am continuing my search for information about the current status of biological control with beetles and other predators. This has been very frustrating, partly because of my slow internet connection, and partly because finding recent research results--since 2014-- is difficult.

But I am, so far, getting the "gist'" so to speak. And I have learned a thing or two. First, Will seems to be right about the lack of imidacloprid restrictions near water or in wetlands, at least generally. Apparently there are no federal restrictions, but I found a statement that says "some managers" restrict its use near water. Also, I was in error about there being a concern for fish. It seems to be for aquatic arthropods, which may indirectly impact fish. So, apparently a "manager" in MD has put on a restriction, but I am not sure if it has the force of law, and if so, what law. If there is such a restriction in force in MD, that would restrict the use of it for maybe as much as 30 or even 40% of my hemlocks. I need to research this more carefully.

Next, with the theory that if in a given state any issue regarding predator control of HWA has general acceptance, the state ag extension office will reflect this, I have been contacting them. This has been very, very interesting. I think I already noted that there are reports of some success in Connecticut with Sasajiscymnus tsugae. Well, the U Conn extension office highly recommends this beetle, and says it gives "effective " control. I would say they recommend, strongly, releasing these beetles. Research reports say that this control is better on some sites than others, so it is not a final, complete solution. But, under the right conditions, the effect of reducing adelgid populations below damaging levels is quite rapid.

Want to get depressed? In NH, Ag. extension says, forget it, don't bother with any control method. --and, this !! The hemlocks don't have enough value to make control worth the expense and effort! Yikes!

I am leaning towards trying the Sasajisymnus beetle. OK, if there is a killing event--wiping out both beetles and adelgids--I can just re-release. There seems to be little immediate prospect for the use --or even research on--any beetle that has a wide variety of prey, making it able to survive when adelgids are temporarily gone. I am sorry to have learned that. There are such predators, but ensuring that they would not have "unintended consequences" would be difficult, so active research on these is essentially absent. Of course, some of the Sasajiscymus beetles may, possibly, survive on the adelgids on white pines. Anyway, the cost of a thousand beetles is very little compared to the cost of chemical treatments. And, if in MD, I can't treat near water, what's the point, since so many of my hemlocks couldn't be treated? Of course, I could chemically treat a few of the larger hemlocks on a "spot" basis, as they begin to decline.

Anyway, I did a search for the adelgids on my timberland, and one place nearby, late last summer, and found none. No point to searching again until late June or July. The people I have so far talked to, are surprised they are not back yet, since the killing was back during the 2012/2013 season.

Well, I will be doing my research, seeking out anyone who may know something, for the rest of the summer, it seems. One contact person I found at the main USDA office in D.C., if you can believe this, grew up just two miles from my place in Garrett County, MD, and rode on the school bus driven by my next door neighbor, and best friend. What do they say?? It's a small world, or something like that??

Well, trying not to be so "scared" about the fate of my timberland, I remain,


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