Forest Health Archives

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

Insects – they can get a bad rap. Many of our humankind categorically view them as pests – agents of uncleanliness, nuisance, or destruction. Sure, it’s hard to appreciate houseflies, ticks, mosquitos and yellow jackets, but the vast majority of them – nearly 100,000 known insect species in the U.S. alone –are simply going about their business and doing no harm to us. Many are even providing services that we take for granted such as disposing of detritus and cycling nutrients.

Larval galleries of wood boring insects in a dead ponderosa pine tree

The same goes for insects in the forest. We in Extension receive many photos and samples brought to us from people who suspect that insects are killing their trees. However, I’m here to tell you that if you have a dead or dying tree, then chances are that even though it is full of insects and their tunnels, it’s usually a case of correlation, not causation. Continue reading →

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

Last week I attended Forest Health: State of the State, a biannual conference put on by OSU College of Forestry. A packed agenda covered insects, diseases, fire, drought, invasive species, climate change, and other topics. I always look forward to this meeting as an opportunity to brush up on my knowledge of these issues. The speakers came from various backgrounds, representing the many forest ecosystems and ownership types we have across the state, and the audience was equally diverse. With that in mind, I’ve tried to distill the takeaways from the conference that seem most relevant to small woodland ownerships in northwest Oregon.

ODF conducts an annual insect and disease aerial survey. Click on the image to be taken to a short video from the air.

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By Amy Grotta and Brad Withrow-Robinson, OSU Forestry & Natural Resources Extension

Group mortality of Douglas-fir in May 2015. Douglas-fir beetle was found in all these trees. Photo Kara Shaw

We have certainly experienced some significant drought conditions lately. Stressed and dying trees are showing up all around the Willamette Valley, with concern that this could lead to beetle outbreaks and still more trees killed. Is it time to throw in the towel, cut your losses (so to speak) and just salvage everything that is looking poorly? Maybe, maybe not. The decision needs to be considered carefully, weighing individual sites and stand conditions along with your objectives for your property. Anybody considering a salvage harvest needs to look before they leap. Continue reading →

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

In a previous article , I wrote that many folks in NW Oregon are growing too many trees in young stands given some common family forest landowners’ objectives, including doing a selective thinning harvest when the trees are in their mid-20s. While on their way towards a variety of longer-term objectives and stand conditions, most people are hoping that their initial harvest will at least break even (when it is sometimes called a commercial thinning). So we need to focus on reaching that first thinning harvest in a timely manner and leaving the stand in a good condition to meet future objectives. Let’s begin by looking at what it takes to have a successful thinning harvest.

My contacts in the business around the mid-Valley tell me that while the first thinning harvest should provide a mix of saw logs and chip logs, most of the surplus trees removed in the thinning need to produce a sawlog or two if you hope to break even or make a little money (a mix of around 2/3 saw logs and the remaining 1/3 chip logs is a rule of thumb used by some). Too many small logs and the operation is costing money. That sawlog will vary according to the mill it is headed to, but is generally 20 feet to 32 feet long with a 6 or 7 inch top. Smaller wood goes to chip and saw or pulp.

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

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.

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

I recently got a call from a fellow whose Douglas-fir trees were covered with globs of pinkish pitch. It looked kind of like candle wax drippings on a Chianti bottle in some Italian restaurant, except it was on the trunks of his trees. As we talked I discovered that it was not an old stand, and the landowner had been out during the nice weather last summer and pruned his trees up six or eight feet to make it easier to get around and to reduce the risk of fire down near the County road. The pitch blobs were at the pruning scars.

Pitch moth evidence on off-site ponderosa pine

The culprit here is the Sequoia pitch moth (Synanthedon sequoia), a common clear-winged moth that attacks many conifer species.

Although commonly seen in town in people’s shore pine and other ornamental pine species, it is not generally a problem on Douglas-fir, or native Valley ponderosa pine except when the tree is wounded. A common and very attractive wound is easily created by pruning live branches during the summer months (April thru September) when the bark is soft and the adult moth is active. Although unlikely to kill your trees it is unsightly and generally avoidable.

Prevention is the best cure.

So this summer, put down those pruning shears. Save that job for the winter months.

Have an image of pitch moth on Douglas-fir you would like to share? email brad.w-r@oregonstate.edu

Fresh pitch moth evidence on an ornamental pine

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.

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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 →

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 →

TreeTopics

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

Category Archives: Forest Health

Many forest insects are mistaken for tree killers

Recap of the 2018 Oregon Forest Health Conference

What to do about those drought-damaged trees?

Spacing young conifer stands

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

Put down those pruning shears

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

Winter Storm Damage

Is Swiss Needle Cast still a Problem?

Watching out for the Emerald Ash Borer & other Invasives

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