Tamarack

[Ron Scott]

DNR: Tamarack mortality a growing concern in the U.P.

The Department of Natural Resources announced today that mortality of eastern larch has been reported in many areas of the Upper Peninsula and in some areas of the northern Lower Peninsula. Eastern larch, also commonly known as tamarack, is succumbing to continued attacks by the eastern larch beetle (ELB).

"Once the ELB builds in an area of tamarack as evidenced by initial pockets of dead trees, continued mortality is likely," said Robert Heyd, DNR forest health specialist. "Those who wish to utilize the tamarack in affected areas are encouraged to harvest their tamarack quickly if ELB is active in their stand."

This bark beetle, which only attacks tamarack, first became an epidemic more than a decade ago. Tamarack was stressed by two consecutive years of defoliation by the larch casebearer in 2001 and 2002. The combined stress of this defoliation with the repeated droughts of the last decade contributed to the buildup of ELB populations. 

Heyd said that from a distance, the most obvious evidence of a current infestation is yellowing foliage that develops by late July or early August. However, often heavily infested trees will not fade before the appearance of the normal fall color change. This makes detecting currently infested trees via aerial surveys or from a distance on the ground difficult if not impossible. Heavily infested trees generally fail to leaf out the following spring.

When infested tamarack are examined at close range, small entrance holes, (averaging just over 1/12 inch in diameter), are the only external signs of an infestation. Under the bark, beetle galleries are etched on the surface of the wood.

In fall and winter, woodpeckers often remove some or all of the bark from infested trees when searching to feed on bark beetles. By late winter and early spring, the removal reveals beetle galleries and exposes the reddish-purple inner bark or white sapwood of the tree. Debarked trees make it easy to identify an infestation.

Eastern larch beetles infestations are fueled by stressing events such as defoliation, flooding, drought, fire, old age, damage from windstorms or snow breakage.

"As tamarack stands age, they become more susceptible to bark beetles," Heyd said. "Because tamarack trees are intolerant of shade, stress from competition may increase as crowns close in older stands. It is important to note that not all outbreaks have been associated with obvious stressors.

"Eastern larch beetles appear to be capable of attacking and killing trees when no predisposing condition or factor is apparent."

The DNR recommends prompt removal of logs and utilization of material larger than 4 inches in diameter to remove breeding material and help reduce infestations. Infested trees, logs and slash should be removed once evidence of an infestation is detected.

For more information, visit www.michigan.gov/foresthealth.

[Gary_C]

I clear cut a stand of Larch a few years ago for the MN DNR in SE MN. The stand had very nice growth but too much mortality. They did mention that larch has many pests and diseases and the one I cut had a lot of open areas that had grown up with 12 foot high buckthorn. Even from the seat of a harvester it was hard to see where you were going.

They called it European Larch and it was planted at the recommendation of the WI DNR. Guess you can't trust those guys from WI.  :D

Are all those larches like eastern, tamarack, and european the same species?

[Jeff]

Back when I reported mine, there wasn't much of a response. In fact I diagnosed it when I was told it was due to dry conditions and I didn't believe that simple drought killed them due to the conditions of death.

Loss of our Tamarack

[beenthere]

Gary_c
European larch :
http://en.wikipedia.org/wiki/Larix_decidua

Eastern larch
http://en.wikipedia.org/wiki/Larix_laricina

[Jeff]

There is a difference. European Larch has been planted in several areas in the Eastern U.P. Usually in end rows of other specie blocks. I posted some photos of some about 10 years ago.

https://forestryforum.com/board/index.php/topic,4497.0.html

[Gary_C]

Here is a picture of some of the larch on the far side of the hill the DNR wanted left standing.


 

And here is what it looked like in most of the stand.


 

It was planted in tight spacing in rows so you can see from the second picture how much mortality they had in the stand. And in SE MN there was not any residual bugs or diseases in the area, but yet they had the high mortality.

[WDH]

Bark beetles have really raised their ugly heads in a lot of places.