Friday, November 4, 2016

EXPLORING THE NIAGARA FRONTIER: Oak wilt sets its sights on WNY

It seems like Western New York forests are under constant attack, in wars that they can’t win.

In the early 1900s, chestnut trees were all but exterminated from our woodlands by chestnut blight. Dutch elm disease wiped out our impressive stands of elms from the 1950s through the 1980s. Ash trees are being attacked by the emerald ash borer. And, beech trees will be totally eliminated from our forests by 2022 thanks to beech bark disease.
As our forests reel from those diseases and pests, and are forever changed, more pestilence is piled upon them. The newest of those threat being posed to WNY forests is oak wilt.

Until only recently, oak wilt was almost unheard of in New York. There was a small outbreak in Glenville in Schenectady County in 2008 that was contained and then found to have recurred in 2013, which was also contained. Then, earlier this year, some was found in Islip on Long Island.

But, an October discovery showed that the fungus is dangerously close to the Niagara Frontier. A homeowner in Canandaigua noticed that an oak tree on their property began dying with no identifiable cause. Samples from the tree were sent to the Cornell Plant Disease Diagnostic Clinic, where they tested positive for the fungus that causes the disease.

There is no known treatment to contain and kill the oak wilt fungus other than to remove infected trees, as well as any surrounding host oak trees. So, the Department of Environmental Conservation took down the trees in question and initiated an emergency order establishing a protective zone prohibiting the movement of oak material out of the immediate area to prevent the fungus from spreading.

The DEC is also conducting aerial and ground surveys to identify additional trees that may be infected, but it is likely too late. Since the infested tree was discovered at the end of the growing season, it makes detective work nearly impossible with all oaks doing their normal color change and leaf drop now. In the fall you can’t tell and infected tree from a healthy tree. Surveys will resume in the spring when dead trees and signs of the fungus are more apparent.

It seems like a lot of concern and work, but it’s absolutely necessary to save the forests from the spread of oak wilt. It is a serious tree disease that kills thousands of oaks each year in the midwest. It is caused by a fungus -- Ceratocystis fagacearum -- which grows in the water-conducting vessels of host trees, causing the vessels to produce gummy plugs that prevent water transport. As water movement within the tree is slowed, the tree starves to death. The leaves wilt and drop off, and eventually the tree dies.

All oaks are susceptible to oak wilt, but red oaks die much faster than white oaks. Red oaks can take anywhere from a few weeks to six months to die and they spread the disease quickly. White oaks can take years to die.

Here are some symptoms of the disease:
  • Brown coloration can develop on leaves starting at the outer edge and progressing inward toward the mid-vein of the leaf.
  • Branch dieback may be visible starting at the top of the canopy and progressing downward.
  • Leaves suddenly wilt.
  • Leaf loss during spring and summer. Leaves may fall when green or brown.
  • Fungal spore mats may develop under the bark, forming pressure pads that can raise and split the bark.

The DEC has asked that the public report any occurrences where an oak tree died over a short period of time, especially if it occurred between July and August. Use the toll-free Forest Health Information Line toll-free at 1-866- 640-0652. You can also reach out to your local Cornell Cooperative Extension office.

It is important that woodlot owners and hikers regularly inspect trees for the disease. If oak trees are eliminated from our forests, especially in the southern tier, it will remove an important food (acorns) that provides sustenance for a variety of animals from deer to bear to turkeys to squirrels.

On top of that, it will eliminate some of the most brilliant trees from our fall landscapes.

A Western New York without oak trees is a frightening thought, so be diligent while exploring the Niagara Frontier.

From the 03 November All WNY News

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