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.
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
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.
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 brad.w-r@oregonstate.edu
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.
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.
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.
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 →
