Thursday, August 21, 2014

Invasive Species in Vacationland

-- by Dan Hilburn

My wife and I spent much of our youth in Maine and many of our relatives still live there. When we go back to visit, we fly from Portland, OR to Portland, ME and cross our fingers that the luggage handlers don’t get confused. Maine and Oregon have a lot in common, including some invasive species. When I’m there, I can’t help comparing their issues with ours. Here are some observations from my recent vacation Down East.

1. Gypsy moths

Gypsy moth populations in Maine are low this summer. I didn’t look for them; I don’t have to. The males are attracted to my wife and I. This year we only saw a dozen and never more than one at a time. On other visits we’ve drawn small clouds of sex-crazed male moths. All because I work in an office with people that handle gypsy moth pheromone. The lures in gypsy moth traps Oregon Dept. of Agriculture staff place around the state every summer are amazing. Even though I never handle the pheromone, my cloths smell faintly like a female gypsy moth and after our clothes are washed together, so do my wife’s. If you want to hear a funny story, ask my wife about the time a flutter of gypsy moths followed her and my daughter on a guided tour of MIT.

2. Knotweed and Beetle Reunion

I don’t remember Japanese knotweed in Maine when I was young, but it is common there now. This year on my drive-by surveys I noticed considerable feeding damage on the new growth. Since nothing seems to feed on Japanese knotweed here in Oregon, I stopped to check it out. I should have guessed, it was Japanese beetle -- another invader. I was witnessing the reunion of old friends: an invasive insect pest from Asia is attacking a non-native noxious weed from the same part of the world! It will be interesting for my counterparts in Maine to see whether Japanese beetles keep the Japanese knotweed from becoming problematic and whether the proliferation of a favorite host plant serves as a trap crop or a nursery for the Japanese beetles.

3. Eastern white pine replacement masts

I love to sail. This summer we were in Camden on a perfect day and couldn’t resist an afternoon sail on a 100-year old schooner. It was awesome. An added bonus for us was a friendly captain that loved to talk about the local windjammer fleet and the challenges of maintaining those beautiful old sailing ships. According to him, finding authentic replacement masts is difficult. Traditionally they were made from trunks of Eastern white pine, which grew tall and straight. Not anymore. White pine weevil attacks young pines, killing the leaders. White pine is still a common tree in New England, but now almost all of them are crooked or have multiple trunks. Our captain said that replacement masts have to come from the Pacific Northwest!

Since introduction of invasive species is tied to global trade and travel,
invaders have had less impact in Oregon than in Maine

Another difference between the two states is the length of time they’ve been settled. Little signs on historic buildings in Maine attest to construction in the 1700’s. Settlement and intercontinental commerce in Oregon is, of course, much more recent. Since introduction of invasive species is tied to global trade and travel, invaders have had less impact on our environment. There are lots of reasons why that is important, the least of which might be that if you want to build a traditional sailing ship with local materials, you can still do it in Oregon!

If you love both states the way I do, my suggestion would be to build your boat in Oregon, then sail it to Maine. If you do that, keep me in mind for the crew.

Wednesday, July 9, 2014

Say Goodbye to Our Black Walnut Trees

Photo from Google Street View
  • Post by Dan Hilburn
Next time you drive out Center Street in Salem take a look at the black walnut trees on the State Hospital campus. Those big, beautiful trees are doomed. If you look up, you can see the tops are dying. Within a decade, they’ll all be dead and gone. The same fate awaits other black walnuts in Oregon. The killer is a fungus that causes thousand cankers disease (Geosmithia morbida) and it’s vector, a tiny insect called walnut twig beetle (Pityophthorus juglandis). This is an invasive species story with a twist – both the fungus and the beetle are believed to be native to North America, though not to Oregon.

Until recently walnut twig beetle was known only from the Southwest where it lived in harmony and obscurity with its host, Arizona walnut.

Until recently, the walnut twig beetle lived in obscurity with its host, the Arizona walnut. 
The beetle expanded its diet to include non-native walnuts.
The killer fungus came along too.

Unexplained die-offs of black walnuts in the mid-West in the early 2000’s were initially blamed on drought and/or the walnut twig beetle. Eventually researchers noticed large numbers of dark cankers under the bark of dead trees. And that led to the 2008 discovery of the associated fungus. The researchers named the fungus thousand cankers disease.

The walnut twig beetle, a type of bark beetle native to the southwestern United States and parts of Mexico, is the only confirmed vector of the pathogen. Apparently, it adjusted to non-native black walnut street trees and expanded its range throughout the West. The fungus hitchhiked with the beetle.

No one has yet figured out a control or management strategy that works. Severe pruning and burning of infested branches may slow the disease, but eventually, even big, healthy black walnuts succumb. Neighborhoods with black walnut street trees are going to look bare when they are removed.

It is sad that we’re going to lose some street trees in Oregon, but the real tragedy will be in the East where black walnut is native and treasured for it’s high-value wood. Several states have enacted quarantines to lessen the risk of human-aided introduction. The biggest threat is movement of infested logs and firewood.

The biggest threat is people moving infested logs and firewood.
If the logs or firewood are put on a truck and moved to a mill, buyer or campsite, the beetles can emerge in a new place and Thousand Cankers Disease jumps ahead like a spot fire started by a spark.

When trees die, people naturally want to sell the trunks and cut up the rest for their fireplaces. If the logs or firewood are put on a truck and moved to a mill or a buyer somewhere down the road, the beetles can emerge in a new place and thousand cankers disease jumps ahead like a spot fire started by a spark. Since it takes several years from infection to the first symptoms, by the time trees start dying no one will remember the shipment of infested wood that inoculated the neighborhood.

For us in the West, its a story of a native beetle/fungus with an expanded range attacking non-native street trees. The take home lesson is that firewood should be bought and burned locally. Don’t take it with you when you go camping out-of-state. The same principle applies to logs. When mills and kilns are local, pests and diseases are less likely to hitchhike to new areas.

I used to have a black walnut overhanging my driveway. The falling nuts were hard on my car and messy to clean up so I wasn’t sorry when the power company cut it down. Black walnuts are the sort of tree you enjoy if it is across the street and belongs to someone else, like the State Hospital -- I’ll still be sad to see them go.

Friday, June 27, 2014

Perception, Reality, and Doing the Right Thing

  • Post written by Dan Hilburn

Why is it so easy to get funding to extinguish fires and so hard to get support for eradicating weeds? That question was asked by one of the speakers at last week’s Oregon Invasive Species Council meeting. It is true -- we’ll spend millions of dollars putting out a wildfire even where they are a natural part of the ecology. The Two Bulls fire near Bend burned through $5 million as well as 7,000 acres. That works out to $714/acre!

On the other hand, we spend barely $0.02/acre on noxious weed EDRR (Early Detection Rapid Response) in Oregon. This is true even though damage from noxious weed invasions can be more serious ecologically than fire damage.
Fighting the Two Bulls fire near Bend Oregon cost $714 per acre.
With invasive species, nothing bad happens quickly;
the threat can be more ecologically damaging, but it is insidious.

We spend barely 2 ¢ an acre protecting Oregon's ecosystems from invasive weeds.


Native plants grow back after fire, but they don’t compete well with invasive weeds. Weed invasions can be described as ecological wildfires in slow motion. That’s the problem – the slow motion part. Fires are immediate and frightening; weeds are slow and insidious. People perceive one as a threat right now and the other as a lower priority. If you ignore noxious weeds, nothing bad happens – for a quite a while, often years.
The Metolius River is being invaded by non-native ribbon grass
The Metolius River is being invaded by non-native ribbon grass.

There was a field trip at the same meeting to see the ribbon grass infestation on the banks of the Metolius River.
USFS Public Notice of herbicide treatments
USFS Public Notice of Herbicide treatment

The USFS has been working on the NEPA documents to address weeds in the Deschutes National Forest including ribbon grass for a decade. Last fall the pieces fell into place and some herbicide trials were put out using a weed wiper and several different rates of Glyphosate and Imazapyr. The wiper was required because of a perception that the herbicides could most safely applied to the invasive ribbon grass and yellow flag iris by wiping it on the leaves. The reality proved to be a little different.

The weed wiper looks like a paint roller on the end of a hockey stick-shaped piece of PVC pipe. In order to work, the wiper has to be saturated with concentrated herbicide. That concentrate drips from the wiper as you work and it is impossible to push down sufficiently with wiper on ribbon grass growing out into the water without immersing the fuzzy part of the wiper. Several of the trial sites had good control on the bank with a halo of surviving ribbon grass in the water. A backpack sprayer would be more effective and if used carefully, e.g. spraying from the water toward the bank, at least as safe.
There's a perception that a backpack sprayer is safer than the wiper.
The reality is different.


 Mike Crumine demonstrating the wiper on ribbon grass
Mike Crumrine, the ODA noxious weed control
expert demonstrated the wiper method on ribbon grass. 

Mike Crumrine, the ODA noxious weed control expert that put in the plots, calculated that the wiper trials used 19.5 oz of Glyphosate and 9.4 oz of Imazapyr. You could do the same work much faster with a backpack sprayer and only use 8.2 oz of Gyphosate and 4.1 oz. of Imazapyr.
The difference comes from using a dilute solution with the backpack sprayer vs. a concentrate in the wiper. Water monitoring during last fall’s trials showed no detectable levels of either chemical in the river. I’d expect the same result with a carefully applied backpack treatment.

I’m not so na├»ve to think we can eradicate invasive weeds on the banks of the Metolius without getting minute quantities of herbicide into the water, but we don’t have a viable alternative. Weed pulling and solarization with plastic have already been tried and discarded as impractical and worse for the river and the native vegetation. Pulling ribbon grass “brings up the whole bottom,” and solarization kills everything under the plastic. If you stand on the Camp Sherman bridge and look downriver, you can see a little island that was covered with plastic to smother the ribbon grass. The little willow that used to grow there died during the solarization. Luckily we have non-persistent formulations of herbicides that are labeled for aquatic use.

So the perception is that wildfires are worse than weeds and that wipers are safer than backpack sprayers. My point is that the reality is sometimes different. We need to fund our weed EDRR programs like we fund fire suppression and we need to use the best available tools when we attempt to eradicate invasive species from high value habitats.