The oak wilt fungus blocks the flow of water and nutrients from the roots to the crown, causing the leaves to wilt and fall off, usually killing the tree. Red oaks (scarlet oak, pin oak, black oak, etc.) can die within a few weeks to six months, and the disease spreads quickly from tree to tree. White oaks (bur oak, chestnut oak, etc.), often take years to die and the disease usually cannot spread to additional trees.
Oak wilt was first discovered in Wisconsin in 1944, but where it originated is still unknown. It has spread throughout the Midwest and Texas and has killed tens of thousands of trees in the U.S.
There are two main ways oak wilt is spread:
Fungal spore mats form just under the bark of infected red oaks after they have died from the disease. During the warmer months, these spore mats emit a sweet odor that attracts sap-feeding beetles and bark beetles, which can pick up fungal spores as they crawl around. The beetles are also highly attracted to fresh wounds in other trees-often caused by pruning. In this way, they spread the fungus from infected trees to healthy trees sometimes miles away. Infected firewood and other wood materials also pose a threat because they can harbor the fungus and/or beetles that can spread the disease.
Spread underground occurs when roots of nearby red oaks graft to each other (fuse together), creating a connection through which nutrients and the disease can move. In the Midwest, large blocks of red oak forests have died from the disease in a single season due to their vast network of interconnected roots. In contrast, white oaks are much less likely to create root grafts, and spore mats rarely form under their bark, significantly reducing the chance of spread from these trees.
Symptoms of oak wilt infection are often very noticeable in red oak species, but aren't easily seen in white oaks.
Oak wilt has been found in four locations in Glenville, Schenectady County. Oak wilt was first was confirmed here in 2008, but resurfaced after treatment in 2013. Two new locations were found in 2017, and one new location was found in 2018. In 2016 oak wilt was then discovered in Islip, Riverhead, and Southold in Suffolk County; Brooklyn in Kings County; and Canandaigua in Ontario County. In 2018 and 2019, oak wilt was found in South Bristol in Ontario County and Middlesex in Yates County, respectively.
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