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Postcard from Scandinavia – Stockholm

TreeTopics - Sun, 05/29/2016 - 9:23pm

Brad Withrow-Robinson, OSU Forestry & Natural Resources agent

Our group of 26 family woodland owners arrived in Sweden this week at the start of the Scandinavia Forestry Tour.

The tour is organized by the Oregon Woodlands Coop along with Washington County Woodlands Association and OSU Forestry &

Woodland owners visiting the Skansen historic museum in Stockholm Sweden

Natural Resources Extension.

The purpose of the tour is to look at forestry practices in this part of the world, meet fellow family forest landowners and focus particularly on the strong role of landowner cooperatives in both Sweden and Norway.

Most of our group is from Oregon, but we have people from four other US states, as well as South Africa rounding out the group.

This is my first electronic post card from the tour, where I will try to share some of the things we are seeing and learning here.


Old traditional buildings at Skansen Museum


View of Stockholm




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Categories: TreeTopics

Effects of drought continue in Valley

TreeTopics - Thu, 05/26/2016 - 11:30am

Brad Withrow-Robinson, Forestry & Natural Resources Extension Agent, Benton, Linn and Polk Counties.

Conifer trees around the Valley continue to show signs of severe drought and heat stress this year. This should not be news to many readers:  young dead trees are now a common sight throughout the Valley.  Also, I wrote about this problem in past Tree Topics blogs (See stories from  May and September 2015 for background) but have new updates for this season.

I think you can expect to continue seeing similar damage to Douglas-fir this year and that symptoms will continue to unfold as the season progresses. Some of the trees damaged late last year did not show that damage immediately. The damage did not become evident until the trees came out of dormancy and began to grow this spring.  Also, the various insect and disease organisms that take advantage of       weak and damaged trees are likely to continue with their business this year, causing new signs of drought damage to show up during the season.  Happily, those players like Douglas-fir cankers and twig weevils do not typically blow up and kill healthy trees.  This suggests things will look much like what we saw and described last year and is likely to continue to unfold this season and maybe longer, whatever weather we get.  “It is important to understand that the effects of drought damage do not go away suddenly when the rain starts again” cautions Christine Buhl, ODF Forest Entomologist “drought can impact the tree’s whole plumbing structure, and affect the growth and vigor of the tree for years.”

What we are beginning to see and anticipate may be different this year is more damage to stands rather than just individual trees, and damage to older and larger Douglas-fir trees than was typical last year. The drought is likely adding to and exacerbating other problems lurking out of view, so crowded stands, existing root disease and marginal sites (wet or shallow soils, southern aspects) can all be expected to contribute to the problem.

Unfortunately, this implies potential economic or forest health issues. Any merchantable tree lost to drought represents an economic loss if not salvaged.  But larger (>8” dbh) drought-damaged Doug-fir trees can also support growing populations of bark beetles, such as the Douglas-fir beetle.  Under the right conditions Doug-fir beetles’ numbers can increase to the point where they can overcome the defenses of healthier trees in the stand.  Drought stressed trees are not generally considered as good a nursery material as winter storm damaged trees  but can support a damaging increase of beetles if conditions are right.  I may need to write more on that later in the season.

We will also likely see drought stress issues in other conifer species. In our local Valley ponderosa pine, it is already causing some limited outbreaks of the California five-spine Ips, a tiny but destructive beetle.  With several generations a year, Ips can rapidly increase in numbers when trees are stressed and conditions favor the insect.  Also, the Ips is able to use much smaller wood (just three inches or more in diameter) than the Douglas-fir bark beetle mentioned above, so even a young planation can provide brood material for the beetle.  Sanitation of dead and dying trees as well as slash materials >3” is a very important control measure for Ips.  For more information on the Ips life cycle and management, see this 2014 article about Ips  or follow links to other resources provided below.

The Oregon Department of Forestry has a series of fact sheets on insects, disease, drought and slash management.  Several are currently being revised, so be sure to check back in July to see the updated versions.




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Categories: TreeTopics

Shrubs for wildlife: Cascara

TreeTopics - Tue, 05/24/2016 - 4:06pm

By Brandy Saffell and Amy Grotta, OSU Forestry & Natural Resources Extension

If one of your land management goals is to provide wildlife habitat, you’ll want to consider keeping a mix of native shrub species on your property. Shrubs provide a host of services to wildlife, including shelter or cover, nesting space, and food from their twigs, leaves, flowers, and fruit. With thought given to species selection and location, retaining existing shrubs or planting them can benefit wildlife without compromising timber growth or forest operations. This is the first article in a series intended to help you recognize some of the “brush” species that may exist on your property, and understand how they may fit with your management goals. Each article will highlight one species that benefits wildlife in northwest Oregon forests.

Species Name: Cascara (or cascara buckthorn, chittam) – Rhamnus purshiana

Description: Growing up to about 30 feet, cascara could be considered a small tree or a large shrub. Its leaves are deciduous, simple, and alternating on the stem. They are oblong (2 – 6” long) and prominently penniveined (having a single central leaf vein with singular veins branching to either side). The leaf edges are very finely serrated or wavy. The small, green-white flower clusters are inconspicuous. The cherry-like fruits are round, 1/3” diameter, and purple to black with a yellow pulp. In winter, look for smooth, gray-brown bark with a patchy appearance. Winter buds are naked, meaning they appear to be small clusters of tiny overlapping leaves.

You may have mistaken cascara for red alder, which has similar looking oblong, serrated, prominently-veined leaves, smooth bark and also grows on moist sites.  You wouldn’t be the first to confuse these two hardwoods.  You can tell cascara and alder apart primarily by the fruits; cascara has a dark purple to black cherry-like fruit while alder has a one-inch woody cone-like fruit (called a strobile). Cascara’s leaves are smoother and glossier than alder’s.

Ideal habitat: West of Cascades in low to mid elevation coniferous forests; Grows on moist, well-drained sites, especially along streams; tolerant of shade.

Wildlife Value: This plant is particularly attractive to birds. For example, the band-tailed pigeon feeds on cascara fruits from July through autumn, often congregating in cascara patches well into the migration season. Band-tailed pigeons are found along the west coast and prefer nesting habitat less than 1000 feet in elevation, putting them in private forestland throughout much of western Oregon. Cascara is also a preferred forage for elk and valuable for pollinators.

Management Considerations: Cascara is not a very fast or aggressively growing species, so it does little to compete with the growth of timber species such as Douglas-fir. Consider retaining existing cascara trees when selectively harvesting in mixed forests. You could also try underplanting cascara in small openings after a thinning. For pollinator or mammal forage, plant in clumps along stand edges to promote flowering and a more thicket-like habit.

If you are interested in learning more about creating wildlife habitat on your property, check out the Woodland Fish and Wildlife website.

Photo credits: Pat Breen, Oregon State University

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Categories: TreeTopics

Don’t forget about pre-commercial thinning

TreeTopics - Wed, 03/30/2016 - 10:01am
Many aesthetic and habitat objectives of family forest landowners come with older, less dense stands like this stand of about 70 years. It is important to get on this path early.

Brad Withrow-Robinson, Forestry & Natural Resources Extension Agent, Benton, Linn and Polk Counties.

In previous segments I argued that many people have too many trees in their young stands   which may be costly and harmful to the long term growth of the stand. Most importantly, having too many trees at this stage can undermine common landowner objectives of growing attractive, longer rotation diverse forest habitats and can force landowners into shorter rotations than imagined.

While this suggests that people should think about planting fewer trees per acre in the future (a step deserving some careful consideration), it highlights the need for pre-commercial thinning in many existing stands to correct overstocking at an early age. This may include your stand.

But pre-commercial thinning (PCT) seems to have fallen out of common practice lately. It has come to be seen (mistakenly, I think) as an avoidable expense rather than an important investment in the stand. An investment that begins to shape how the stand will look and behave in the future and which adds resilience and options to the landowners’ woodland portfolio.

The idea of PCT is to avoid harmful overcrowding later by removing excess trees early on. PCT lets the remaining “leave trees” grow faster and larger before serious crowding sets in. This means that trees reach a usable size sooner, and hopefully allows the very important first thinning harvest (also called a commercial thinning) to be done “on time” when the stand is in its 20’s.  This first thinning harvest  is costly and the difference between it being another  big expense for the landowner rather than breaking even or even paying some small profit, often comes down to the size of the trees harvested.  PCT is meant to ensure that this very important thinning harvest operation can pay for itself.

Ideally, young Douglas-fir stands in Western Oregon should be thinned when the dominant trees are about 15 feet tall, or about 10 years old around here.  Yikes, that seems early.  Frankly I don’t know many people who are thrilled about thinning trees they just barely got established and free to grow.  People are looking forward to the trees’ shade suppressing hated weeds like blackberries and broom and are inclined to postpone PCT until the weeds decline and the stand begins to “look crowded”.

Why thin so early? Even by the time trees are 15 feet, you can already begin to distinguish the good trees from the bad.  The trees are past browse and should be beating the weeds.  Once that has happened, the sooner you remove the extras and limit competition among trees, the stronger the beneficial effects and the less the costs of the PCT will be.  Yes, it may be possible to delay until trees are 30 feet tall, but waiting until crowns close and competition begins means a loss of some growth that you would rather have on your leave trees.  Also by the time trees look crowded to many people, it is getting very late.

Referring to the illustrations of the previous article, the recommended  timing of a PCT is meant to occur well down in the uncrowded green zone, well before competition gets going in the Goldilocks zone.   The PCT is meant to shift your stand from the right-hand column to the left-hand column, with more room and  new growth potential until it is time to you your first thinning harvest.

An earlier PCT also means it can be done more efficiently and cheaply. Small trees can be felled much more quickly with less slash building up. There is little concern about stand stability, or delayed growth response when trees are thinned early.

My point is that if an area was planted at a 10×10 spacing (440 TPA) and had good survival, the stand will get too crowded before the trees are big enough for a thinning harvest.  If that is the case, it should be PCT’ed down to at least 300 TPA, meaning you may need to remove a quarter to a third of the trees (110 to 145 TPA).  This is a lot of work, even when trees are small, which takes us to some good advice for many family forest landowners: “Thin early and thin often”.

I’ll give some strategies for thinning in a later article.

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Categories: TreeTopics

Resources in the fight against weeds

TreeTopics - Tue, 02/23/2016 - 9:21am

Brad Withrow-Robinson, Forestry & Natural Resources Extension Agent, Benton, Linn and Polk Counties.


Pretty much every landowner I know has a weed issue.

Some are fairly short term and narrow, such as controlling common weeds in a new tree planting. Others are much longer term and less defined, such as keeping invasive species at bay in the woodland, or perhaps encouraging  native plants in a meadow or streamside restoration.

There are multiple approaches to weed management, including preventing new weed introductions, mechanical or physical control such as mulching or mowing and the use of herbicides. Most people use a mix of two or more of these approaches, with many including herbicides as one of the methods they use.

Here are some key resources to help you manage your weed issues.


Invasive Weed Identification and Management EC 1563 

It is important to know the enemy, and this is a good place to start, beginning with the 3-page introduction. This publication goes on to describe the identifying characteristics, origin, habitat, ecology and management strategies for selected invasive weeds in the Pacific Northwest. This list is not inclusive of all invasive weeds, but focuses on the most dominant or potentially invasive species that plague us. Check PNW Weed Management Handbook for current herbicide recommendations.


The Nature Conservancy’s Weed Control Methods Handbook

A useful resource for many types of landowners, the Weed Control Methods Handbook: Tools & Techniques for Use in Natural Areas provides detailed information about weed control techniques including manual and mechanical methods, grazing, prescribed fire, biological control, and herbicides.  Check PNW Weed Management Handbook for current herbicide recommendations.


2015 PNW Weed Management Handbook  

This handbook is designed as a quick and ready reference for weed control practices and herbicides. It covers an array of weed control issues, but its real value is in providing professionals with current information about herbicides used in agriculture, forestry and other situations. If you use herbicides as part of your weed management strategy, then you ought to be consulting this book to find important details on the effectiveness and selectivity, rates, and timing of individual herbicides. Like so many other things in life, timing is everything in weed control too.

Important sections include:

  • Pesticide Safety (Section B)
  • Agrichemicals and their Properties (Section c)
  • Forestry and Hybrid Cottonwood (Section K)
  • Christmas Trees (Section P)

The pesticide safety section is essential reading.

Hardly Shakespeare’s sonnets, the chemical properties section has important facts about individual herbicides, including both common name and trade name, mode of action and toxicity.

The forestry section includes an excellent discussion of vegetation control with herbicides, covering woody and non-woody (herbaceous) plants separately. The section includes a table indicating effectiveness and selectivity of forestry-registered herbicides on different species of plants; recommendations for control of woody species, and recommendations for grass and herb control for planting and establishment. Herbicides will be listed by their common name (e.g. clopyralid or metsulfuron) so many readers will need to refer to Section C to find familiar trade names.

The Handbook is available in print but since it is revised annually, it is recommended to go on-line to refer to or download relevant sections.

Caution! The handbook is not intended as a complete guide to herbicide use. Before using any chemical, read the container’s label. A chemical must be thoroughly tested before it can be recommended for a specific use. Following the label’s recommendation can prevent many problems from arising due to wrong use of a chemical. Any use of a pesticide contrary to instructions on the printed label is illegal and is not recommended. Herbicide application is a forest operation requiring notification of ODF.


Calibrating and Using Backpack Sprayers

Backpack sprayers are relatively easy to use – and to misuse. This video (EM 9039)   and printable pdf of PNW 320 describe basic sprayers, their components and how to use them appropriately. It also outlines how to calibrate the sprayer, calculate application rates, and mix pesticides.


Preventing Herbicide Drift and Injury to Grapes  EM 8860   

Anyone using herbicides near a vineyard needs to understand the damaging effects that common herbicides can have on grapevines and steps you need to take to reduce the risk of herbicide drift and injury.

So good luck out there and please be smart and be careful in all your weed control efforts. Chemicals and power equipment each have dangers and justify judicious and cautious use, especially on rugged ground and sensitive areas.


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