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.
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 →
Brad Withrow-Robinson, Forestry & Natural Resources Extension Agent for Benton, Linn and Polk Counties
In my previous post, I summarized what I think we know about this ecological whodunit. In this post, I look at what it might mean for landowners in the area.
We seem poised for another stressful summer. May 2018 has turned out to be one of the driest on record, and we are unlikely to catch up in June. Long term forecasts are for another warm dry summer. We will just have to wait and see how it unfolds. But whatever happens this summer, I think we can expect to continue to see more sick, dying and dead trees. There are several reasons for this.
First, many trees are already stressed or injured by the past hot drought events and are in a vulnerable condition. While not yet lost, this stress makes them less resistant and more susceptible to the insects and diseases that are lurking about. A mild summer, or several mild summers would help. But even then they will not recover immediately. Their earlier stress and injuries also hamper their ability to recover and rebuild their resistance, even under good conditions.
An analogy might be of me falling off a ladder. The injuries I suffered when I hit the ground continued to affect my health and recovery long after I stopped falling (it is harder to exercise with a broken leg). It will take a while to recover, even if I stay out of trouble. It will take longer (or could kill me) if I keep falling off the ladder. For the trees, each of these summers is like another fall from my ladder.
Second, some trees are already lost. It may not be obvious, and they may still have needles, but they have been mortally wounded or have already been attacked by insects and will not recover, however our summer turns out. It is just a matter of time before those losses become apparent. Continue reading →
Brad Withrow-Robinson, Forestry & Natural Resources Extension Agent for Benton, Linn and Polk Counties
Many of our readers have been tracking this issue over the last several years through the articles on this site. But I imagine many of you are wondering what to expect next, or are being asked by friends and neighbors who are concerned about your trees or theirs. Or just wondering what is going on. What to say?
So, here is a synopsis of what I generally see going on, and the consequences. A bit risky to do, given the role of individual sites and specific conditions. But this is such a widespread phenomenon, it warrants some interpretation, even at the risk of over-generalizing. But I provide the antidote at the end: links to more detailed information.
It is hard to miss all the dead and dying trees in the area. I have been getting dozens of calls about them. So what is going on, and what is to blame? It seems time to revisit this sylvan whodunit: What is killing all these Willamette Valley trees?
Who is involved? Douglas-fir is by far the most frequent casualty, along with other conifers such as grand fir and some ponderosa pine. But trees of many sorts are being affected –
hardwoods as well as conifers, both native and non-native. Many of the usual suspects – different beetles and fungi- can be found at the scene too.
What is happening? Symptoms often include dying branches and dead tops, low growth and vigor, sparse crowns, what we have called the “Willamette Valley crud”. It is now often progressing to the death of the tree. This may be happening to individual trees or groups of trees. The younger trees are usually the first involved at a site, eventually joined by older trees.
Where is it happening? This is certainly a Valley-wide phenomenon. But within the Valley, we are seeing the most significant damage in certain situations more than others. Sites with seasonally wet, poorly drained soils, or sites with rocky or shallow soils, exposed south facing aspects tend to be most hard-hit. These are places that we think of as marginal sites for most conifer trees. Our conifers are well adapted to the area, but not every site. 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.
By Amy Grotta and Brad Withrow-Robinson, OSU Forestry & Natural Resources Extension
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.
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.”
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.
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.
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 firstname.lastname@example.org
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.