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Fir Fungus Now an Epidemic

As if the Twin Harbors timber industry hasn't had enough problems, now there is a threat facing tree farmers with Douglas fir plantations.

It's a fungus called Swiss Needle Cast, and while it doesn't often kill trees by itself, it does make them much more susceptible to other diseases.

"They haven't determined all the stages of the fungus yet. It's kind of like AIDS in that respect," says Dick Moulton, a consultant and former Grays Harbor County extension agent.

The fungus infects Douglas fir needles, causing them to turn yellow and brown and then fall off. Because conifer trees don't regenerate leaves like hardwoods, a typical healthy Douglas fir will carry from four to eight years' worth of needle growth. The fungus eats all the sugars in the needle that the tree needs for food, weakening the tree and causing it to "cast," or prematurely, drop, its needles.

Even if the loss of needles doesn't kill the tree, the loss of nutrients can severely stunt its growth, and the already weakened tree is forced to expend even more energy to fight the fungus off, making it more susceptible to other diseases, insects and dry weather.

"I can go from the Canadian border to the Columbia River, and virtually every Douglas fir needle I turn over will have this fungus," says Omdal, a forest pathologist with the Department of Natural Resources in Olympia. "In stands under 25 years old, there's perfect conditions for the fungus. The canopy tends to be thicker, and there's more humidity and poor air circulation underneath."

First identified in early 1900s

The fungus was first identified in Western Washington in the early 1900s, and was never a problem until recently, according to Omdal.

"It didn't cause any problems before. It was native to the forest; it evolved with the trees, and as long as the trees weren't stressed, there was no problem," says Omdal.

"Why is it a problem now? One theory is that we have a new super-strain of the fungus, a particularly virulent form that mutated out of the relatively innocuous original.

"Another hypothesis is that we're using seed stocks that aren't appropriate for the sites they're planted."

The fungus spreads quickly in "monoculture" environments where the trees are all the same species and all the same age. Trees between 10 and 30 years old are particularly vulnerable danger.

"We have a major infestation going on," says Washington State University Extension Agent Don Tapio. "The Department of Natural Resources is doing aerial surveys as we speak to see how far it's spread. I went down to Ocean Shores a week ago and could hardly believe the discoloration in the forest, and it was the same just the other day in Pacific County."

City of Montesano's tree farm hit

In Montesano, where the city owns about 5,000 acres of timber-land, city forester Ron Schillinger says the disease is infecting about 1,400 acres.

"Our really critical stands are the stands between 5 and 15 years old, which are almost exclusively Douglas fir. There we've got a problem," Schillinger says. "We're afraid if we don't do something the successive years of buildup will stress them out. Then, between the needle cast, insects and other diseases the stands will eventually die."

Montesano is planning on spraying about 750 acres with a fungicide called Bravo-500, with the intention of breaking the fungus's normal life cycle.

"In looking at the damage, the key to determining severity is the needle retention," Schillinger says. "Most or our trees still have three years of needles, even though the needles have been infected. We've kind of divided our strategy into three or four treatment alternatives. In the stands over 20 ears old, it looks like there's enough needle retention that the trees will be able to outgrow the disease. If they don't, there's always the possibility of salvage logging not losing money."

Another of Montesano's options, in the stands where there are several species rather than just Douglas fir, is to do nothing. Swiss Needle Cast doesn't affect other tree species, and even if all of the Douglas fir in the stands die off, Schillinger thinks there will be enough timber left in other species to make up for the loss.

"In my experience since 1971 in the timber industry I haven't seen or heard of this kind of problem in Douglas fir," the city forester says. "Our thinking is maybe the buildup of the fungus has just gotten out of hand because of the large number of acres in this area that are entirely in Douglas fir, and also because of the unusual weather patterns we've had."

Weyerhauser scientist Dr. Will Litke says that while the disease hasn't become a major problem for the timber giant yet in Washington, the company is still making effort to stay on top of it.

"Our number one concern here is surveying for impact," Litke says. "we've been working on needle cast since 1985. Our concern is that we keep our stands healthy and growing well. Our main approach is understanding the relationship between needle cast and the Douglas fir stock. We want to understand more about the disease because it's part of the Douglas fir ecosystem."

Omdal notes that the first real problem infestation was in Oregon in the mid 1980's, when seedlings from Eastern Oregon were planted in the much wetter western side of the coast range in the Tillamook area. Planting the seedlings in an unfamiliar environment put stress on them and lowered their resistance to the fungus.

"It used to be that people in the Christmas tree business were very concerned about Swiss Needle Cast, and they're not concerned now because it's primarily confined to Douglas fir," says Moulton. "For Christmas Tree plantations, the old rule wasn't to spray, it was to destroy the infected trees. That's kind of a severe system, but it worked. The growers I know have avoided that by going to other species like Noble firs, which make them more money anyway."

Wet climate a factor

The fungus was initially confined mostly to the coastal regions of Oregon and Washington, but the extraordinarily wet weather this past winter has so far proved perfect conditions for it to spread inland.

"Let's just say it's been greatly enhanced by cool wet spring and copious amounts of rainfall this spring and last winter," Tapio says. "If you have rural acreage and you have Douglas fir trees the best sign of infection is the discoloration. There are fungicides you can use, but it's not that easy to spray a 40 or 50 foot tree.

Another problem with the fungicides is that they prevent the fungus from infecting a healthy tree, but they can't cure an already infected one.

"I'm not even sure that heavy aerial fungicide spraying is going to be that effective, anyway," says Moulton. "Even if it was, no timber company wants to have that image of spraying the whole green world. Even if that wasn't really accurate, that's the label they'd get."

Perhaps most ominous, says Omdal, is the possibility that heavy spraying of fungicides might create a new, super-resistant strain of the fungus, much like casual use of antibiotics has created new resistant strains of bacteria.