Two bad trends conspire to kill off area pine trees

By CHAD DAY and KAREN DILLON
The Kansas City StarThe 22 pines stood dry and brown alongside a ball field in Kansas City’s Pleasant Valley Park.

Until Thursday, when park employees started cutting them all down.

“It’s not a good year for pine trees,” said Forest Decker, manager of forestry and conservation with the city of Kansas City.

Not on Kansas City public land, where hundreds of the more than 6,000 pines already have died, and not in backyards.

If you’ve noticed dead and dying pines as you drive around the area, you’re witnessing the victims of two problems that are hitting local pines especially hard this year after four or five bad years.

Pine wilt, caused by microscopic worms, kills trees in two months or less. That’s what hit the Pleasant Valley Park trees.

“This year is probably the worst year we’ve seen as far as pine wilt,” Decker said. “It’s just a couple weeks, and they are done.”

The other problem: Tip blight, a fungus that can be treated if caught in time.

“I’m anticipating a real heavy year on tip blight,” said Dennis Patton with Johnson County K-State Extension.

Why this year?

The stress of an ill-suited climate on trees that don’t really belong here, and perhaps climate change that makes the weather’s mood swings more dramatic.

“A stressed tree is not a healthy tree,” Patton said. “Just like a human body, a stressed human body is more open to attack.”

Pine wilt

Pine wilt is caused by the pinewood nematode — a microscopic worm — that clogs the tree’s vascular system, depriving it of water. The nematodes are carried by pine sawyer beetles from tree to tree, quickly killing pines in their paths.

The trees at Pleasant Valley Park in Clay County were pocked with pea-size holes left by the sawyer beetles. The interior of the worst trees showed purple or bluish-black stains, signs that bark beetles flocked to the trees once they began to die from pine wilt. The needles were brown, some beginning to gray.

The nematodes’ main targets are non-native pines, such as the Austrian and Scotch pines at the park, said Bryon Sosnowski, an urban forester with the Kansas City parks department. The trees have to be removed as soon as possible to keep the pests from spreading.

Once they infiltrate a tree, there’s no saving it.

The worsening problem could be caused by the impact that climate change may be having on the sawyer beetle population, said David Tippets, a spokesman for the Rocky Mountain Research Station, a research and development center for the U.S. Forest Service.

Because of warmer temperatures, insects that only reproduced, for example, once every two years, are now reproducing every year or even twice a year, Tippets said.

Marc Linit, who studied pine wilt and sawyer beetles for more than 20 years at the University of Missouri, said he’s observed a correlation between hot, dry summers and an increase in pine wilt the following spring.

“At the most basic level, native pines have evolved with the nematode,” Linit said. “They have evolved an effective defense mechanism.”

Non-native trees haven’t. And when planted in a climate such as Kansas City’s, the problem is compounded.

The pinewood nematode also has been particularly destructive in Nebraska, said Don Janssen, educator for the University of Nebraska-Lincoln Extension in Lancaster County.

“It is kind of a tenacious little critter,” Janssen said.

It’s not nematodes but mountain pine and bark beetles that have chewed through 2½ million acres of Colorado and Wyoming pine trees.

Climate change is helping the mountain pine beetles flourish, experts say. The beetles used to be killed off during cold winter months, but because of milder temperatures in winter, that no longer happens.

The mountain pine beetles have become so plentiful that swarms of them have been picked up on Doppler radar, said Mary Ann Chambers, public relations officer for the U.S. Forest Service Bark Beetle Incident Management Team.

Most of the non-native pines in the Kansas City region were planted as windbreaks or for ornamental purposes in the ’50s and ’60s. The problems with pine wilt started hitting those trees as they reached maturity.

Preventing pine wilt is difficult and costly, say Wes Ory, owner of Heritage Lawns and Irrigation in Olathe, and Mark Young, a board certified master arborist.

They purchased the equipment to inject pine trees with chemicals to prevent pine wilt, but have yet to use it. They attribute that to the cost — upward of $300 — which is a lot for customers to shell out.

Tip blight

Experts expect pines to be hit hard by tip blight this year because of the cool, wet spring.

And while pine wilt kills trees faster, tip blight has affected more pines in the Kansas City area.

The airborne fungus gets worse in wetter springs because it’s easier for spores to cling to the branches, Patton said.

Tip blight can be treated with pruning and fungicides, but if left unattended it will kill a tree.

On an affected tree, a few limbs will begin browning back from the tip and worsen during the summer.

Sosnowski saw signs of tip blight on the pines at Pleasant Valley Park.

Routinely spraying the trees with fungicides would help prevent tip blight, Sosnowski said, but the city has too many trees and too few employees to do it.

It makes sense for a homeowner with a few trees, he said.

As for Christmas trees this year, don’t worry, farmers say. They’ve seen fewer problems, perhaps because they’re cut down before they’re old enough to develop them, said Debbie Barnett of Tom’s Christmas Tree Farm in Kansas City.

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ADVICE
•If tip blight is caught early, it can be avoided by pruning the affected branches and applying a fungicide.•Arborists only have preventive measures to help fight pine wilt. Once trees show symptoms, it’s too late. In fact, a tree with pine wilt should be cut down and buried, burned or chipped up.

•Don’t plant Scotch or Austrian pines. They aren’t suited to areas with a mean summer temperature that exceeds 68 degrees — such as Kansas City.

•White pines are a better bet. They’re a hardier tree whose natural habitat is nearer to this area. Cedars are also stronger. Native evergreens such as junipers or bald cypress also are good replacements.

To see the electronic story at KansasCity.com, click here.