How will ash borer spread affect your woods?

MADISON, WIS. – The tree-killing emerald ash borer has spread further across Wisconsin, leading to a statewide quarantine, with new rules imposed around how forest owners and businesses handle ash wood.

Emerald ash borer, which was discovered in eastern Wisconsin in 2008, has now been found in 48 of the state’s 72 counties, according to a March news release from the Wisconsin Department of Agriculture Trade and Consumer Protection. The exotic insect, which has killed hundreds of millions of trees in the U.S., had previously been found in all southern counties and two in the northern part of the state.

Prices for ash wood in the state have been high recently, according to the Wisconsin DNR, and a statewide quarantine could prompt more harvests by landowners and others once it goes into effect.

“The trend is definitely upward over the last year, because of the export market specifically,” said Sabina Dhungana, a forest products specialist with the agency. “Business owners are also saying they’re buying ash wood, thinking there may not be (as much)” because of EAB.

That harvest dynamic played out in Michigan, where EAB was first located near the Detroit Metro airport in the early 2000s, which led to the decision of officials to cut ash trees in state forests.

"We've made a concerted effort to cut all the ash we can," said Doug Heym, a Michigan DNR official. "If you don't cut it, you will lose it."

Heym, who tracks pricing in Michigan, said ash and mixed hardwood pulp sales stayed level after the quarantine, but sawtimber prices dropped under $100 per MBF, before eventually coming back up.

In Wisconsin, data compiled by Forest Data Network, a pricing information service, shows that log prices on both public and private foresters have risen markedly. Over the past 10 years, data shows the price per thousand board feet of ash has ranged from a weighted average of $111 to $195. Average prices across the state were more than 40% higher in 2017 than in 2010.

Many signs points to demand staying strong, thanks to strong domestic and international markets for lumber and industrial products.

Ash, which makes up about 7 percent of Wisconsin forests, is seen generally as having higher lumber production value, due to fewer knots and is sometimes referred to as a “white wood,” making it well-suited for baseball bats, tool handles and furniture parts. China is a major export market for Wisconsin ash, Dhungana from the state's DNR said.

“They prefer the look of ash wood, and they’re also aware of EAB and what’s happening in the U.S.,” she said.

Meanwhile, log supplies across Wisconsin and other Great Lakes states have increased, according to a recent survey put out by the Nebraska Forest Service, with some respondents reporting the most they've seen in years.

A quarantine also imposes restrictions for the transportation of many types of ash products, including logs, pulp, firewood and untreated lumber. An agreement can be obtained from USDA or state officials as long as measures are taken to prevent the spread of EAB.

According to the state's trade agency, known as DATCAP, industry was in support of the statewide quarantine based on the challenges of transporting wood between counties outside of the quarantine. Only two counties remained that hadn’t either had EAB detected or were adjacent to a county that had.

If the 1⁄2-inch long metallic green beetle with copper hues is detected on ash trees, the results can be devastating. EAB research in Michigan and Ohio has shown significant damage to ash species, including black, green and white ash with no consideration of density, basal area, diameter or tree health. Models developed in Michigan predict an infected healthy forest will lose 98 percent of ash trees in 6 years.

"We are losing ash at a significant rate," reported Michigan's Heym. "There is more ash mortality than growth."

In many parts of the U.S., EAB infestation has caused a jump of inventory of Ash logs available to mills as owners attempt to harvest the trees before they die and lose value. That's likely to affect prices in the short term and long term because as the supply begins to diminish, it will likely lead to increased prices as less is available to be harvested.

The beetles leave a “D”-shaped exit hole in the bark when they emerge in spring, and woodpeckers like to feast on the larvae, which can be a sign of devastation, according to the EAB Information Network, a partnership between the USDA Forest Service and Michigan State University.

Maintaining ash in forest stands can help maintain species diversity and other benefits, reasons the Wisconsin DNR doesn’t recommend removing all ash prior to EAB infestation.

Alterations of a management plan depend on several factors, including quarantines, distance from EAB infestations, stand composition and age, management goals and wood markets.