Does Chipping Pine Attract Bark Beetles?

Lop and scatter method of slash disposal
Lop and scatter method of slash disposal. Photo: USDA

As many forest landowners already know, pine slash has a tendency to attract pine bark beetles. There are several recommendations for slash disposal to mitigate this problem. Two common methods — lop and scatter, and chipping — focus on eliminating bark beetle habitat while retaining the nutrients contained within the slash on site.

The lop and scatter method involves cutting slash into smaller pieces (less than 12 inches in length, less than 3 inches diameter) and scattering the pieces throughout the site. Chipping involves running slash through a chipper and scattering it throughout the site, similar to lop and scatter. While there is no chance that bark beetles can infest the chips, it is still possible for bark beetles to infest the pieces in the lop and scatter method. The chances of the beetles being able to successfully produce brood in these pieces is pretty low, as they will likely dry out before the larvae are finished developing. Both methods are a reasonable substitute to piling and burning when burning is prohibited, BUT…

Anytime you cut pine, you are releasing volatiles. Volatiles emitted from pine contain chemicals called monoterpenes. Some monoterpenes have been shown to attract bark beetles and are often included as part of the lure when trapping for bark beetles.

female bark beetle
A female bark beetle eating the phloem of a tree. Photo: USFS

If you are choosing between lop and scatter and chipping, which is best? You would think that chipping would be the better choice since there is no chance that bark beetles can infest the chips. But a study by Fettig et al. (2006) showed that chipping in ponderosa pine stands attracted bark beetles more so than the lop and scatter method, particularly in the spring. Why would this be? As it turns out, directly following treatment chipping releases much larger quantities of attractive monoterpenes than the lop and scatter method. If large quantities of attractive monoterpenes are released at a site where the slash has been chipped and bark beetles arrive, where are they going to go? They cannot infest the chips. They are going to go to the standing, residual trees. Although the act of thinning should increase the health and vigor of the residual trees, it will take at least a year for those trees to respond, therefore, you may wind up with bark beetle infested leave trees.

So, does this mean you cannot chip? Not necessarily. Some landowners prefer to begin thinning treatments on their property in the spring; it is finally warm (but not too warm), the snow is melting off, and they are ready to go outside and get things done. Other landowners find that they have to thin in the spring for various reasons (the snow is too deep during the winter; fire season often prohibits the use of machinery in the summer; contractors cannot fit everyone in during the bark beetle “off” season). Unfortunately, as Fettig et al. (2006) found, the response of bark beetles to high concentrations of volatiles released from chips is more significant in the spring because a large segment of the beetle population is most active during this time.

If you plan on chipping, it would be best to avoid treatments in the spring. The best time to chip (or do any sort of management that releases pine volatiles for that matter, including pruning), would be in late summer (late July/early August) through early winter (December). When producing chips, avoid piling them and absolutely do not pile chips at the base of any residual trees.  Spread the chips out in the sun if you can. The quicker they dry out, the quicker the volatiles will dry out, and the less overall bark beetle risk there will be.

By Melissa Fischer, forest health specialist Washington State Department of Natural Resources, Northeast Region,


Fettig, C.J., J.D. McMillin, J.A. Anhold, S.M. Hamud, R.R. Borys, C.P. Dabney, and S.J. Seybold. 2006. The effects of mechanical fuel reduction treatments on the activity of bark beetles (Coleoptera: Scolytidae) infesting ponderosa pine. Forest Ecology and Management. 230: 55-68.

Using Drones for Better Forest Access and Management

drone hovering
An Autel Robotics X-Star Premium drone hovering over land trust property. Photo: Mark Gray

The Chehalis River Basin Land Trust owns or holds conservation easements on over 4,400 acres of forest land in southwest Washington. Land Trust representatives visit these lands each year to develop restoration plans, and monitor for invasive species, garbage dumping and other damage. Many of the land trust’s holdings lack roads and are accessible only by foot or boat. Some of the lands contain extensive wetlands that are not accessible even by foot.

To improve the value of their monitoring efforts and to facilitate long term observations of site conditions, the Land Trust has been using an Android tablet loaded with GIS and GPS software. With these tools examiners have access to maps, as well as photos and GPS tracks of previous site visits in the field. QGIS ( and Handy GPS ( are two great free software solutions for field mapping. Free is an important consideration for non-profit, volunteer organization like the Chehalis River Basin Land Trust.

However, these tools don’t help with access to areas that are too wet or steep to be reached by foot. To overcome this challenge the land trust has been investigating the use of an unmanned aerial vehicle (or drone) as a relatively low-cost way to access areas ground based observers can’t reach.

Land Trust board members and volunteers recently had an opportunity to experience a drone in action when Grays Harbor College forestry instructor Alex Bastos provided a demo of the College’s drone at a site east of Aberdeen in the Chehalis River Surge Plain. The site is a wetland, dissected by a network of sloughs draining into the Chehalis River and is not accessible by foot or boat. The Autel Robotics X-Star Premium drone provided high resolution video and still photos of areas that the land owners had never seen. The drone flies at a height of up to 400 feet and has a range of about 1,800 feet from the controller providing plenty of range to cover much of the parcel. The drone can stay airborne for only fifteen minutes but can cover a lot of ground in this short time.  You can see a video of the drone in action at

While using a drone requires a certain level of skill to make the best use of its range and flight time is limited by battery life, it has the potential to be a useful tool to survey inaccessible lands quickly and cost effectively.

The Chehalis River Basin Land Trust holds over 4,400 acres for conservation, protection, and restoration in our beautiful Basin. From the rolling hills and prairies south of Puget Sound to the saltwater estuaries on the Pacific coast, the Chehalis River watershed stretches across 2,660 square miles. Waters from five different counties flow into Grays Harbor by way of the Chehalis River, forming the second largest river basin in Washington State. To learn more about the Chehalis River Basin Land Trust, visit their website at

By Mark Gray, board member, Chehalis River Basin Land Trust

Ask an Expert! Answers to Landowner Management Questions


I have knapweed and rush skeletonweed on my property (which isn’t huge, 80 acres, and the infestation isn’t enormous, just enough that it’s an issue for me). I spray, re-spray and re-re-spray, using 2,4-D and Milestone at 2 oz and 3/8 oz, respectively, per gallon, the dose the county weed guy recommends. The weeds never seem to die. I don’t think I’m wrong when it seems like I treat the same weeds year after year.

Do I increase the amount of chemical? Use a different chemical? Do something radical like dig up the weed and, with a tiny artist’s brush, paint undiluted 2,4-D directly on the root? Am I doing something wrong? Thanks.


Weeds never seem to die.

Thanks for your question and your determination to manage a couple of troubling noxious weeds.

Do I increase the chemical? A recommendation, that is part of an integrated weed management approach, would be that you monitor your upcoming season spray application closely to observe the impacts of your treatment. The rates and materials you describe should work well on the knapweed and skeletonweed. Treatment timing is also very important for these two perennial weeds. Treatment timings should include both the spring and fall to reduce the amount of new seed production. Timing must also consider periods when soil moisture is adequate and plants are actively growing to get good movement of herbicide into the plants. Both of these weeds are known for their abundance of seed produced and the seed viability in the soil (3 years for rush skeletonweed, 8 years for spotted knapweed).

Spotted knapweed and rush skeletonweed
Spotted knapweed (left) and rush skeletonweed (right) are aggressive weeds that can easily take over disturbed areas and rangelands. Photos:  Washington State Noxious Weed Control Board.

Taking the time to identify the boundaries of the weed populations and then working through the area in a grid pattern to minimize misses is time well spent. Additional time should also be given to scout outside the area to pick up any outlying plants. After the initial treatment, return to the site in about two weeks, to spot treat any new seedlings or any plants previously missed and beginning to bolt. Treatments in the fall season to target any plant rosettes that survived through the summer is very effective in reducing these perennial weeds.

In addition, always evaluate and consider the planting of competitive native vegetation in the area of the infestation to compete with these invasive weeds. If the weed site is frequently disturbed and can’t be managed differently, the location may require some annual maintenance to keep the weeds from spreading to other areas.

Distribution maps of spotted knapweed and rush skeletonweed.
Distribution maps of spotted knapweed (left) and rush skeletonweed (right) across Washington State.  Photo: Washington State Department of Agriculture.

Given the scale of your acreage and infestation size, individual treatments of digging, cutting and daubing stems with herbicide wouldn’t be very efficient for these fast moving weeds. However digging may be appropriate for those single, outlier weeds that are found elsewhere on your acreage.

By Bill Wamsley, Noxious Weed Control Board Coordinator, Lewis County,

Introductions: New WSU Extension Forester and Stewardship Notes Editor

Patrick Shults. Photo: WSU
Patrick Shults. Photo: WSU

Before we sign off on this edition of Stewardship Notes, I would like to introduce myself, Patrick Shults, as the new Extension Forester for WSU in southwest Washington. A little about myself: I was born and raised in Michigan and received a B.S. and M.S. in Forestry from Michigan State University. Much of my background has been with environmentally focused non-profits, where I’ve gained experience leading volunteer teams and educating the public in fields like sustainable forestry, urban forestry, and habitat restoration. I also have a history of writing forest management plans for small forest landowners and a strong background in agroforestry and non-timber forest products. I’m very excited to be bringing this experience here to build education programs and assist landowners in this part of the country. Forestry and education are my two greatest passions, which means this is essentially a dream job. I’m looking forward to meeting landowners and making connections as I continue to settle into this role.

As a part of my new position, I will also be taking over as the editor of Stewardship Notes (wishing Carol Mack a happy retirement!). As I get accustomed to the area and the many issues facing small forest landowners I will be keeping in mind the opportunity to address these concerns through Stewardship Notes. In particular, I hope to highlight the landowner perspective by inviting your submissions for future editions of SN. This could be in the form of a personal narrative about you and your land, you can send your forest management questions and I will have them answered in the next edition, or maybe you just want to share something you find interesting with the small forest landowner community. Since landowners are the target audience for this newsletter, I think a great way to have your concerns and interests recognized is to have you submit them, so don’t be shy!

Please send your submissions to and feel free to contact me with any questions via email or phone at (360) 740-1213.

Announcements, Events and Other News

If you are reading a paper copy of this newsletter, links for these events can be found at the WSU Extension Forestry website:

Forest Stewardship Coached Planning

If you own wooded property, our flagship course will teach you how to assess your trees, avoid insect and disease problems, and attract wildlife. State experts will help you develop your own Forest Stewardship Plan to keep your woods on track to provide enjoyment and income for years to come.

  • Aberdeen (Grays Harbor County) – Mondays starting April 23rd

2018 Invasive Forest Weed Control Field Practicums

  • Bellingham – May 12, 2018
  • Kent – June 2, 2018
  • Mount Vernon – September 15, 2018

2018 Forest Owner Field Days

  • Eastside (Spokane) – Saturday, June 23rd (details coming)
  • Westside (Woodland) – Saturday August 18th (details coming)

Workshops and Trainings

  • Hands-On Chainsaw Safety and Maintenance Training – May 17th

Can’t find the event you were looking for? Visit or contact: