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
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

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

Douglas-fir killed by drought
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.

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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
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
Fresh pitch moth evidence on an ornamental pine

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

drought stressYoung 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.DSCN2137

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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Large purple plastic triangular boxes illustrate monitoring activity
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.

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by Chal Landgren, OSU Extension Christmas Tree Specialist

Anyway it is spelled- Yellowjacket, Yellow Jacket or Yellow-Jacket, these insects are feared and hated not only by picnickers, but by many working in the woods, and in Christmas trees.  For Christmas tree growers they can inflict physical and economic pain, since they are unwanted hitchhikers in many shipping destinations.

First some biology- These are not honeybees. Rather, two predatory insects in the genus Vespula, whose common names are the Western Yellowjacket and German Yellowjacket. The Western

Comparison of queens.  Photo courtesy ODA
Comparison of queens. Photo courtesy ODA

Yellowjacket (V. pensylvanica) is a common native.  Yes, they are predators, but also scavengers, which makes them a pest at summer BBQs and picnics.  The German yellowjacket (V. germanica)  is an uncommon non-native species (not wanted in Mexico).  Both these insects feed on other insects as well as nectar, honeydew and fruit.

Queens will overwinter in protected locations above or below ground and emerge in May. After the queen emerges she will begin her colony which eventually can include hundreds to thousands of workers. Fertilized queens will emerge again in October or November. Males (stingless) begin to emerge in large numbers in late July. 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
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

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Submitted by Glenn Ahrens, OSU Extension Forester, Clackamas, Marion & Hood River Counties

Alder flea beetles are particularly active this summer as they go about their business of skeletonizing leaves on red alder trees. I have seen this come and go over the years, and generally flea beetles are not a serious threat. Flea beetle flare-ups in the forest usually run their course after 2-3 years, after which their population crashes – similar to western tent caterpillar infestations. Healthy alder trees with good vigor are usually not seriously affected. Stressed alder trees – particularly those in dense thickets – may die after 2-3 consecutive years of flea beetle infestation. If you like your red alder trees and want to promote “good vigor” the best way is to 1) avoid growing alder on poor alder sites and 2) keep trees well-spaced to ensure large healthy crowns.

Summer must be coming to an end. I say that not because the kids are going back to school or the tomatoes are (finally) starting to turn red, but because today I got my first call of the year about a strange and striking looking insect.

This is a banded alder borer. It is a native wood boring insect, but it is not considered a forest pest because it generally infests dead or downed wood (people often find them on their firewood piles). This insect is often confused with the Asian Longhorn Beetle, which is one of the nation’s most un-wanted invasive pests. If you find a large, black and white insect with long antennae, chances are it’s the banded alder borer (the good guy), but to be sure, look for a white head with a large black dot on it. See the photo above.

I am not sure about the banded alder borer’s life history, but I think the adults must be most active in August and September because that’s when the calls and emails start to come in.