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 →
By Amy Grotta, OSU Forestry & Natural Resources Extension – Columbia, Washington & Yamhill Counties
I’ve been taking part in an OSU Extension program called Oregon Season Tracker (OST) for about five years. OST is a citizen science program where volunteers keep track of rainfall and plant phenology (seasonal growth patterns) and submit their records to national databases. OST also connects natural resources managers, landowners, educators, and others in the community with researchers and their science. At our office in St. Helens, we have an approved rain gauge which we try to check each morning, and a phenology “garden” consisting of two large Douglas-fir trees and some native shrubs.
When I first got involved in OST, my motivation was practical. I thought that having some consistent record of weather and phenology patterns would ultimately be useful in my work in Forestry & Natural Resources Extension. I wasn’t quite sure exactly how it would be useful. But I figured that since weather affects trees in many ways, something would come of it; and even if not, I would be helping scientists with THEIR research questions. 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.
Brad Withrow-Robinson, OSU Forestry & Natural Resources Extension agent, Benton, Linn and Polk Counties.
We have been dedicating a fair amount of screen space and class time lately to the idea that many family forest landowners would benefit from thinning their young stands. We explored the reasons to consider young stand thinning (YST) as well as some approaches in a series of posts on YST . YST is consistent with the situation and goals of many family forest landowners, which often include growing older and more diverse forests.
That said, like many other well-grounded activities, YST is not without some potential drawbacks.
Few of them are significant enough to justify not thinning at all, but each requires some thought and consideration to avoid unintended consequences. We present some of those potential drawbacks that you need to consider when planning a YST, along with some links to other information, below. Continue reading →
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