forest health Archives - Page 2 of 3

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

Young Douglas-fir trees with dying branches or tops turning brown, then red have become a common sight all around the Willamette Valley this spring. What is going on?

This “flare out” of branches and tops are classic drought symptoms in Douglas-fir, which we are linking to last year’s weather when we had a particularly long, dry and very hot period late in the summer. Late season drought injuries to the stem and leader do not always show up when they occur, but often express themselves the following spring as trees start to grow. We have these drought damage events from time to time here in the valley, most recently in 2013 and again before that around 2000. Older trees typically have milder symptoms, but the many older, flat-topped Douglas-fir trees you see are a reflection of past droughts and non-fatal damage. Continue reading →

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

Winter storms seem to inflict damage to trees and forests somewhere in the area most years. Winds, snow and ice can damage individual trees or entire forest stands- breaking out branches, snapping the main trunk or tipping over whole trees, leaving landowners with a mess and many unexpected decisions.

This winter has been an exception in the severity of the November 2014 ice storm that battered a swath of the interior Coast Range from the Kings Valley area south to Mary’s Peak (see previous article). This unusual event caused irregular and spotty damage reflecting fairly small differences in aspect and elevation. Many landowners are still surveying the damage and considering their need to salvage and wondering if they can thin the damage out while leaving a healthy stand. Damage is severe enough in some cases to be forcing the decision to clear cut and replant young stands rather than the early thinning they were due for.

Continue reading →

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

The short answer, unfortunately is ”yes”, but the news was clearly mixed when researches and land managers gathered for the Annual Meeting of the Swiss Needle Cast Coop (SNCC) in Corvallis on December 4. They met to review progress in learning more about this native disease, how it affects trees and forests, and how to manage forests in the affected areas.

The meeting included updates on this year’s aerial survey, progress in establishing the next generation of research plots across western Oregon, the effects of thinning and other management activities on foliage retention and growth, and improvements in remote sensing and growth modeling abilities. Some of the things I picked up this year included:

The disease is intensifying but not expanding greatly. That is to say, we are certainly seeing more severe disease symptoms in places, but mostly within areas where it has been a problem before, and the footprint of highly affected area does not seem to be growing very dramatically. The disease was detected on over 586,000 acres in 2014, which is up significantly from 18 years earlier (131,000 acres in 1996). The main area of impact remains near the coast, generally within 25 miles, except for an active area around Mary’s Peak.

Thinning pre-commercially does seem to help improve needle retention, but only in the healthiest trees and in the lower part of the live crown.

Unlike other stressors, such as drought, it seems that SNC-weakened trees are not highly attractive to Douglas-fir beetles.

Continue reading →

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

While most residents of the Willamette Valley and Cascades foothills experienced unseasonably cold temperature in mid November, residents and landowners in the central Coast Range endured a serious ice storm. This was not a region-wide storm, but sure packed a punch in certain areas, with some people saying the damage caused may be as bad as or worse than that caused by the infamous Columbus Day Storm. I have not heard of any additional damage from a freezing rain event on December 1.

The main area affected is centered around Blodgett and Burnt Woods, stretching north through Kings Valley into Polk County and south to the flanks of Marys Peak. The McDonald Forest was shut down for nearly a week due to falling ice, limbs and whole trees, closing roads throughout the research forest and creating hazards to workers and recreationists. Crews and equipment are working to reopen forest roads throughout the area. Continue reading →

Large purple plastic triangular boxes illustrate monitoring activity

by Brad Withrow-Robinson, OSU Forestry & Natural Resources Extension, Benton, Linn and Polk Counties and Wyatt Williams, ODF Invasive Species Specialist

A large purple box hanging in the trees along Airlie Road last year caught my attention at 55 mph. Pulling over I recognized it as a monitoring trap for one of the current invasive species threatening Oregon’s woodlands. Luckily ODF and others are watching out.

The emerald ash borer (EAB), an invasive insect from Asia, has killed an estimated 100 million trees and caused more than $3.5 billion dollars’ worth of damage and property value losses in the eastern U.S. since its arrival in the 1990’s. All 16 North American ash species are threatened with extinction, including our native Oregon ash. The furthest west population yet detected is in Boulder, Colorado – a day’s drive or so from Oregon in a motor home. Originally introduced to the U.S. via wood packaging material, it is now spread across the continent in infested firewood.

Continue reading →

A ratty-looking incense-cedar near Corvallis

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

You’ve probably noticed that incense-cedar (Calocedrus decurrens) is looking pretty ratty in the mid-Willamette Valley this year.
Driving around, I am seeing many trees showing a mosaic of healthy and dead foliage. The dead foliage is reddish to muddy brown and may be individual fronds or small branches. It often seems to be in the lower parts of the tree. Symptoms seem to vary dramatically between trees, even adjacent ones.
So what is going on? Quite likely any of several things.
Incense-cedar rust is a common and familiar foliar disease. It is most recognizable in the spring, when it produces orange gobs of jelly-like goo on the infected fronds. It commonly kills small sprays of leaves and causes a loss of tree vigor in severe cases. Continue reading →

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

It is shaping up to be another exciting year in forest health here in northwest Oregon. Fortunately, neither of the two defoliating insects currently on the scene are serious threats to forest or human health, but they are certainly causing a stir.

Right now, Columbia County is in the midst of the largest documented western tent caterpillar outbreak that Oregon has seen in two decades, according to the Oregon Department of Forestry. I first noticed a few tent caterpillar clusters on one site in the area two years ago. Last summer, our Extension office received many calls as the caterpillar population built up. Aerial surveys done a few weeks ago show that at least 13,000 acres are affected in the county this year.

Map and aerial view showing extent of western tent caterpillar defoliation, early June. Affected areas are brown in the photo. Source: Oregon Department of Forestry

Continue reading →

Storm damage may lead to beetle problems in ponderosa pine

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

Not to be a fear-monger, but there is talk about last winter’s storm damage leading to some future beetle problems for ponderosa pine in the Valley.

Now, bark beetles are generally weak predators of trees. Damage is often limited to marginal sites, with beetles usually attacking trees weakened by other stresses, such as drought or flooding. Generally this does not pose a great threat to the other, healthier trees in the area.

But I recently spoke to a couple landowners concerned about bark beetle attacks in their ponderosa pine. Continue reading →

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

Our Master Woodland Manager trainee class wraps up next week, after sixty-plus hours of learning and sharing together over the past six months. As an instructor, what I’ve enjoyed the most of this experience is that over half of our instructional time has been spent in the field, doing hands-on activities designed to encourage critical thinking about the day’s topic.

For each class session, we’ve tried to hone in on a few key themes. One theme for our forest health session was the importance of being observant in diagnosing a pest or disease. Our instructor, Dave Shaw, had the class look methodically for signs and symptoms at each site we visited. Where on the tree is the problem noticeable? Was there a pattern to the damage across the stand? What’s going on at the ground level? Any signs of chewing, wounding or scraping? What else is going on in the area?

Twice that day, we learned how easy it can be to prematurely jump to conclusions about a forest health problem, without pausing to get the full picture of what’s going on around you. We went to one site where there was extensive mortality of young Douglas-fir trees. Knowing that laminated root rot is the #1 most common disease in the area, when we walked into the stand and saw symptoms consistent with laminated root rot, most of the group who had seen it before agreed that it was the likely cause. But it was not until we started excavating around some of the dead trees that we found signs of two other root diseases, as well. Continue reading →

By David Shaw, OSU Extension Forest Health Specialist

Insects of Oregon white oak are causing some damage this summer, and you may be seeing trees that look completely brown or have scattered dead branches (distinct brown foliage clumps all through the crown). There are two different issues that have emerged around the Valley this summer: whole tree defoliation/leaf eating by the western oak looper (Lamdina fiscellaria somniaria); and scattered branch death caused by the combination of a twig gall wasp (Bassettia ligni) and the western grey squirrel.

The western oak looper (a type of inchworm) is a flashy defoliator that is a native in the Willamette Valley. The caterpillars are messy feeders, hang by silken threads, and leave browned mostly consumed leaves all over the tree, giving the tree the appearance of being dead. But the oak trees usually come back the next year. Historically, the outbreaks have been of short duration in any single area (typically one or two years) and the oak trees rarely suffer long term damage even though the defoliation may be spectacular. However, when conifers such as Douglas-fir are intermingled with affected oaks, they can also be defoliated in an outbreak and impacts to the Douglas-fir may be more severe. Continue reading →

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Serving small woodland owners and managers in the Willamette Valley and northwest Oregon

Tag Archives: forest health

Many Douglas-fir with dead tops and branches in the Willamette Valley this year

Winter Storm Damage

Is Swiss Needle Cast still a Problem?

November Ice Storm hits Coast Range

Watching out for the Emerald Ash Borer & other Invasives

What’s causing all that die-back in Incense-cedar?

The boom-and-bust life of defoliating insects

Will 2014 be the year of the Ips?

Pest Scene Investigation

Oregon white oak in the Willamette Valley, Summer 2013…..Some in-your-face issues

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