Thousand Cankers Disease detected in Chester County Pennsylvania trees

Earlier this month, the Pennsylvania Department of Agriculture announced the quarantine of four additional Pennsylvania counties because of the detection of Thousand Cankers Disease.

The affected counties are Chester, Delaware, Montgomery and Philadelphia. The disease was found in fields with black walnut trees in Franklin, London Britain, and Lower Oxford townships in Chester County. Samples were verified by the state and federal departments of agriculture.

The disease is caused when Walnut Twig Beetles, which carry a fungus, tunnel beneath the bark of walnut trees, causing small cankers to form. The beetles, dark brown and similar in size to a poppy seed, are extremely difficult to detect. As more beetles attack the tree, the number of cankers increases, slowly starving the tree of nutrients and causing the tree to die within 10 years of initial infestation. Early symptoms of the disease are yellowing of leaves and foliage-thinning of the upper crown of the tree. As the disease progresses, larger limbs die followed by the trunk.

The quarantine restricts the movement of all walnut material including nursery stock, budwood, scionwood, green lumber and firewood. It also covers other walnut material living, dead, cut or fallen including stumps, roots, branches, mulch and composted and uncomposted chips. Due to the difficulty in distinguishing between species of hardwood firewood, all hardwood firewood is considered quarantined.

Non-compliance with the quarantine order could result in criminal penalties of up to 90 days imprisonment and a fine of up to $300 per violation, or a civil penalty of up to $20,000 per violation.

Image Credit: Karen Snover-Clift, Cornell University, Bugwood.org

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