How much can you compromise when buying seedlings?

TreeTopics - Thu, 11/19/2015 - 3:50pm

By Brad Withrow-Robinson, OSU Forestry & Natural Resources Extension agent, Benton, Linn and Polk Counties

I got a call a while back from someone having trouble finding the seedlings she wanted and wondering if she could make do with something else.

A bed of western hemlock seedlings in nursery

The caller wanted large, bare root hemlock seedlings from her Coast Range seed zone, but all she could find was container stock from a Washington seed source, and wanted to know if that was an ok choice.

Given the current seedling supply situation, I am thinking many people may be facing a similar choice between the “right” planting stock type and the “right” seed source, if they have any choice of seedlings at all.

When is compromise a sound choice?

The seedling you buy reflects the way it was grown, resulting in a size and shape that makes it more or less suited to different conditions in the field (as well as more or less expensive), and is thus an important factor in successful establishment. We use terminology such as 1-1 or 2-0 to convey cultural history of different seedling types.

The seedling you buy also has a genetic heritage, usually described by its area and elevation of origin, which reflects its adaptation to particular environmental conditions. We commonly use seed zones as a guide to help assure adaptation of seedlings to their planting site. When not done right, we see unhappy trees that are often described as “off-site”.

So we are talking about different scales of impact, and so different scales of risk.

Seed zone map

If you look at the seed zone map for western hemlock (from Sources of Native Forest Nursery Seedlings at right) you’ll see they are fairly generous in their north-south orientation and rather narrow east to west. This suggests that you may be able to move hemlock a fair distance north or south, but not as far east to west.  A short distance one direction can be as important as a long distance in another. This is consistent with the experience of Rick Allen, a Forester for Starker Forests, who says that difference in behavior of coastal sources can be dramatic if planted inland no further than Blodgett or Burnt Woods, rather than near the coast. You can find more about that in the publication above as well as in this publication on selecting native plant materials. This issue is likely be of even more concern in the case of climate change.

Yes, people are experimenting with longer moves beyond the traditional seed zones, but unless being done with good bioclimatic information (likely with help of a computer model), it is more likely to be a roll of the dice than a sound management strategy.

So back to the type and scale of the risk. An inappropriate stock type may make the task of plant establishment harder (due to browsing or competition), and be quickly evident. But we can and often do address this culturally (with Vexar tubes or more rigorous weed control). An inappropriate seed source is likely to affect long term growth and survival, but not to be evident for years or even decades. Poor adaptation cannot be easily addressed afterwards.

All this seems to add up to an answer that it might be okay to buy a less-than-ideal type of planting stock if you think your management skills can provide for the shortcoming, but since we are talking about trees in the forest rather than tomatoes in the garden, you ought to be much more cautious about compromising on source of origin. In that case, you would likely be better off delaying the planting a year or so to get the genetics and stock type you want.

Which is just what the caller did.

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Seedling supply is an emerging issue for woodland owners

TreeTopics - Mon, 09/21/2015 - 4:27pm

By Brad Withrow-Robinson, OSU Forestry & Natural Resources Extension agent, Benton, Linn and Polk Counties

Here is something you should know: Seedlings are in short supply for this winter’s planting season, and the situation is unlikely to improve any time soon.

So what is up? The seedling situation represents something of a perfect storm, with demand rising just as production is down. This is bad news for the folks who’ve noticed timber prices are up a bit and are thinking of a harvest sometime soon.

But that is part of the problem. We have seen an increase in demand for seedlings in response to an improved timber market which has upped the harvest and replanting activities. The Christmas tree market is also looking up. Then there is the whimsy of Nature. Extreme weather, such as the November 2014 freeze, have been causing significant nursery losses in some areas and for certain species (such as western redcedar right now). The drought and this summer’s massive fires will create new and on-going demand for seedling production across the region.   Demand unmet this year adds to the demand next year. Then add to that the news that some large corporate growers are saying they will not be selling to the public any more, and you can see why seedlings are hard to find.

A bench of Douglas-fir plugs

On the production side of the equation, the crash in harvest during the recession led to a dramatic oversupply of seedling, leaving nurseries to absorb the loss. This caused several mid-sized nurseries to go out of business, shrinking current nursery capacity and causing reluctance of many nurseries to “seed an extra bed” to meet some unknown future need. Remember it takes a couple years to grow most seedlings, and nobody has a reliable crystal ball.

Family forest landowners typically get their seedlings from two pools: Seedlings grown on speculation of future need, and production over runs from contracts for large corporate landowners. Both of these pools have declined recently, and are likely to continue to decline.

What makes many people really nervous is that the situation is not likely to be resolved quickly, nor easily. There are many obstacles to a durable solution. These include reduced production capacity, dwindling reserves of harvested seed, increased production costs, low margins and (understandable) reluctance of nurseries to expose themselves to excessive risk. Remember, we are not talking about a single product, but about a very large suite of products: seedlings for over a dozen conifer tree species and many more hardwoods and shrubs, of several distinct stock types, for 10 distinct seed zones, many with multiple elevation bands. These myriad products all result from decisions and a production process triggered two years earlier. It looks like the perfect storm brewing.   It is a wonder there are any seedlings available at all.

So what is a person to do?

Plan ahead. We say this all the time, but now we mean it. If you have waited for the rain to fall before making a call, you are likely out of luck this year. Seedlings from many species, stocktypes and seedzones have been sold out since June. But I said “likely”, so get on the phone and call around at least and get on a waiting list. The seedlings have not been lifted and sorted, so supplies are still uncertain. You can get in line for any that show up beyond the current estimate, or if someone backs out of an order. You can find a list of area nurseries to call, along with an idea of what thy typically produce by referring to the Oregon Department of Forestry’s Sources of Native Forest Nursery Seedlings. Another valuable resource to help you locate seedlings is The Forest Seedling Network.

Western redcedar

Going forward, plan to order far ahead, before the sawdust flies. Growing seedlings on contract likely takes a larger order and bigger commitment than many family forest landowners want to take on, but getting in line at the start of the production cycle might boost supply as well as secure your piece of it. Expect to see the cost of trees expand as nurseries adopt methods to get the most out of each pound of seed, from each square yard of bed of square foot of bench.

Finally, communicate with and support the efforts of landowner groups such as OSWA or Tree Farm, the Committee for Family Forestry and the Oregon Department of Forestry which are looking for solutions to the problem.

My thanks to Rick Barnes (Barnes and Associates), Kathy LeCompte (Brooks Tree Farm), Dan Kintigh (Kintigh’s Mountain Home Ranch), and Bob McNitt (The Forest Seedling Network) for providing background on this story.



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Categories: TreeTopics

Pruning season is now open

TreeTopics - Fri, 09/18/2015 - 12:38pm

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

For those so inclined, pruning season is now open.

There are many reasons people pick up a saw or loppers to prune up their trees in young stands.   The most common motivations I hear are accessibility, aesthetics and fire resistance/prevention.  Even pruning up just a single- eight foot “lift” can serve any or all of those objectives. 

People want to be able to walk freely around the place without fighting through dense brush the whole way. So many prune to open trails or corridors. This allows them to get to favorite spots more easily, or just get around and see how things are doing. It lets them enjoy the property more (daily walks or bird watching) and also to more easily take care of tasks like spot spraying invasive weeds. Pruning a whole block of trees improves not just access but opens up the line of sight. It quickly changes the look and feel of a young stand and gives the stand an open aesthetic that many people like.

Some people prune up a young stand to increase its fire resistance by getting flammable branches up off the ground. This may be a particularly strong motivation if their property borders a public road, in which case it might make sense to also pull back the pruning slash a few rows in to help keep the ground bare.

There are also some people who are inspired by the thought of their trees producing clear, knot-free wood in the years to come. That objective requires a series of lifts to a short log length (20ft) on selected trees, but deserves a separate article.

Pruning does take some time and exertion, but is pretty straight forward if you follow a few simple rules:

Cutting flush leaves a large wound, damaged collar and bole.
  • If pruning into the live crown, you should get it done from the late fall to late winter, rather than summer, as I cautioned last summer. The bark is now tight and insect pests such as the sequoia pitch moth are less likely to be attracted to wounds made in the winter. Pruning dead branches is ok any time.
  • Prune close, but not flush with the trunk. [See photos below]. This prevents injury to both the bole of the tree and the branch collar. The collar is the raised area at the base of the branch. Leaving the collar allows the tree to heal over the pruning wound more quickly. It is better to leave a stub than cause injury to collar or bole. Something to keep inmind if using power tools.
  • When pruning young trees, be careful not to be too enthusiastic. The rule of thumb is to leave at least half the tree’s total height in live crown.
  • Be mindful of potential sun scald. Factors increasing damage risk include: edge trees with SW exposure, drought conditions, pruning in late summer before the rains, leaving the minimum live crown ratio.

So you pruning enthusiasts, get out there and get some exercise while feeling good about the gym membership fee you are not paying.



Note the collar at the base of the branch cut just outside the collar .. leaving a minimal wound and undamaged collar tissue to rapidly close the wound.

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Summer 2015, DROUGHT! And Heat. A Forest Health Report

TreeTopics - Wed, 09/02/2015 - 6:23pm

By David Shaw, Forest Health Specialist, OSU Forestry and Natural Resources Extension

Douglas-fir killed by drought

The summer of 2015 is shaping up as a big year for drought and drought related forest health issues throughout Oregon, but especially in the Willamette Valley, SW Oregon, and in Eastern Oregon.

In late summer, it can be very difficult to discern whether insects, disease, or drought and heat are causing tree dieback and deaths, but we are becoming pretty confident that drought and heat together are influencing much of what we see.  In this report I outline and describe some of the more common problems we are seeing with conifers and hardwoods as of early September.

Drought related issues

In severe drought, trees may die with no associated biotic agents such as bark beetles or canker diseases. However, it is very common to find dead trees with these agents too.


Douglas-fir in the oak zone of western Oregon (the drier area of the Valley and on heavy clay and shallow dry soils at lower elevations) is having an especially hard summer, with some sites outside the oak zone also showing drought effects. The general symptoms are top dieback, branch flagging, and whole tree mortality. These symptoms may or may not be directly related to a biotic organism. The major ones are branch cankers, bark beetles, and twig weevils. All these organisms seem to do well on Douglas-fir during drought, and this year is no exception. We also believe root diseases are exacerbating the issue, but it can be difficult to discern. Twig weevils and branch canker diseases are very common on young Douglas-fir during drought, and both are known to increase attacks on drought stressed trees.

Douglas-fir twig weevil damage. Whitney Schmike photos.


Left: Douglas-fir branch flagging, likely from dought and canker interaction. Right: Douglas-fir canker. Note the brown dead bark area and green live bark. Branch is flagging.

Bark beetles

Douglas-fir beetles initiating an attack this spring. The tree had a red crown already, likely from drought. Photo Kara Shaw.

Bark beetle attacks on conifers increase during drought. This is the case for Douglas-fir, grand fir and other true firs, as well as pine. In these conifers it often results in top dieback, but can also result in whole tree mortality. We do not have the results from this year’s the statewide survey yet, but it appears that bark beetle activity is going to be really up. However, symptoms of bark beetle attack vary with beetle type and drought effect. For example, typically when a Douglas-fir is attacked by Douglas-fir beetle in April or May, the tree crown does not go red for many months, perhaps not until late fall or even early the next spring. However, this year many trees that were attacked in the spring were turning red right away, by mid-summer. This may be because they were already dying from drought, and this may also be exacerbated by existing root diseases.

Group mortality of Douglas-fir in May. Douglas-fir beetle was found in all these trees. Photo Kara Shaw

Many declining Douglas-fir trees have an associated stress cone crop, a smaller than normal abundant cone crop that is hypothesized to be related to the last gasp of the tree to reproduce before death. For a stress cone crop to hang on a tree in early 2015, means they likely formed in 2014, indicating many of the trees with top-dieback this summer have been suffering for two years or more.

Douglas-fir with stress cone crop. These cones formed in the previous year, therefore indicating stress beginning in 2014 or earlier. Photo Kara Shaw.

True fir/Grand fir

The fir engraver bark beetle attacks all true fir, but is especially important on grand fir and white fir during drought. We anticipate a lot of grand fir mortality this summer, but it will not become evident until fall, as the trees may take a few months before showing red foliage. Throughout the range of grand fir, the species has expanded its site occupancy with fire suppression, even in the Willamette Valley.   During drought, many of these sites are not suitable for fir and mortality may become very common. Root diseases may also exacerbate the mortality.

Foliage loss in conifers

Many conifers lose foliage in a drought, theoretically as an adaptation to reduce water loss through leaves. Although this is poorly understood, this summer it is quite common to see conifers like Douglas-fir or ponderosa pine losing two-year-old foliage and older. There may be interactions with foliage fungi/diseases, but it is very difficult to differentiate what is happening during mid-summer.

Foliage browning in hardwoods

Foliage browning in hardwoods is becoming more and more common throughout the region as drought intensifies this summer. Partial tree crown and whole tree crown foliage browning is already present in big leaf maple, Oregon ash, and cottonwoods. We anticipate Oregon white oak will also begin showing symptoms within the next month. We believe this is an adaption to prevent whole tree mortality, a type of early season senescence, and next spring most these trees will flush and be healthy if rains return this winter. Significant foliage browning is also being reported in California black oak in southern Oregon already this summer.


And, a few NON-drought issues…

Oregon white oak with branch flagging from Cynipid wasp and squirrel interaction.

Oregon white oak has had a big year for small branch dieback in some areas of the Willamette Valley. This is associated with a complex which involves a twig gall wasp (Bassettia ligni)(Hymenoptera: Cynipidae) in which the grubs develop under the bark of small twigs. The western gray squirrel is attracted to these areas with gall wasp grubs and the squirrel debarks the twig. If you see branch dieback in oak (red-dead foliage in clumps), check just below the dead foliage and see if you see the twig debarked. It is very characteristic and easy to see generally. This issue is common in the Valley, but year-to-year it varies in locations and intensity. This year it is particularly common in the Corvallis area and along the west side of the valley.

Bigleaf maple also begins showing branch dieback this time of year. This often is associated with western gray squirrel feeding damage, but no gall wasp is involved, the squirrels just like young maple bark. Again, to verify this is squirrel damage and not drought or other issue, check to see if the branch has been debarked below the dead leaves.

Bigleaf maple with dead branch flagging (left) and showing debarking by squirrels (right)

Swiss needle cast along the coast is still persisting and the aerial survey again showed over 500,000 acres of visible disease symptoms from the air. This was restricted to sites within about 20 to 30 miles from the coast. Occasionally young stands also show symptoms along the Cascade foothills. However, in the Willamette Valley and SW Oregon in general, the foliage loss we are seeing this summer is likely not caused by Swiss needle cast. See the Swiss Needle Cast Cooperative website.

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TreeTopics - Fri, 08/21/2015 - 10:28am

By Amy Grotta, OSU Forestry & Natural Resources Extension – Columbia, Washington & Yamhill Counties

Like just about any small woodland, the Matteson Demonstration Forest has its share of invasive weeds. Besides familiar and ubiquitous foes such as Scotch broom and thistles, one of particular concern is knapweed.

Meadow knapweed, photo by Eric Coombs, OR Dept of Ag,

With purple flowers emerging from roundish bases at the top of a tall stalk, knapweeds superficially resemble a sort of spineless thistle, and in fact they are relatives of thistles, botanically speaking. They are biennial (2-year life cycle) to perennial plants and reproduce by seed. Fairly inconspicuous in the winter and spring; at this time of year, their purple flowers betray their location on and along roadbeds and other disturbed areas.

There are several species of knapweeds (Centaurea spp.) in Oregon, and all are classified as noxious weeds. Meadow knapweed, actually a hybrid of two other species, seems to be the most prevalent in the Willamette Valley.   Spotted knapweed is more of a problem on the eastside though has been documented on the westside too.

These two species can be tricky to tell apart, but we think we have meadow knapweed at Matteson, based on its wider distribution on the westside, the shape of the foliage and the color of the bracts (the tiny scale-like leaves at the base of the flowers).

So why are knapweeds a problem in forestlands? The biggest concern is their impact to native plant communities. They are tough competitors that can crowd out other desirable herbaceous plants, posing particular challenges to pasture or grassland managers, or those trying to restore meadows or oak savannahs. Even for those that do not have those particular objectives for their property, knapweeds are “road runners” in that they are easily spread by foot and vehicle traffic along roads and trails. So if you find that you have a knapweed infestation on your property, you can do surrounding property owners a favor by keeping it in check.

On the Matteson tract, knapweed is largely confined to gravel roads and open areas along the roads. Our main concern is limiting the spread of the weed, not only on this property but also to other College Forests and to other properties. For that reason, we are trying to keep OSU College Forest vehicles off the property as much as possible, so that tires and vehicle undersides do not pick up the seeds.  Multi-year herbicide treatments will also likely be necessary to reduce knapweed on the property; although because the weed is also prevalent along the county road ringing Hagg Lake, we may be fighting an uphill battle. We will be regularly surveying where our access roads join up with county roads and neighbors to contain and prevent its spread.

Roadbed infestation of knapweed with flowers and maturing seed heads, August 2015. Same road last October, showing mature seeds.

For more on knapweed management, consult these fact sheets: Invasive Weeds in Forestlands: Knapweeds from OSU Extension and Meadow Knapweed Best Management Practices from the King County Noxious Weed Program.

Thanks to Michelle Delepine from West Multnomah SWCD for her helpful expertise on this subject.

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