Garden Variety: Emerald ash borer infestation expands in Kansas

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Emerald ash borer

Last week, the Kansas Department of Agriculture announced that they had confirmed the presence of emerald ash borer in Spring Hill. The finding of this invasive exotic pest will lead to expansion of a federal quarantine and is a reminder to area residents with ash trees on their property to consider options for management of their trees.

Emerald ash borer was first confirmed in Kansas in 2012 in Wyandotte County. It has since been found in Atchison, Doniphan, Douglas, Jefferson, Johnson, Leavenworth, and Shawnee counties. This progression in Kansas appears to be natural spread outward from the original known infestation site.

The insect was first discovered near Detroit in 2002 although experts believe it may have been in the U.S. for a decade or more before detection. It has since spread to 35 states and five Canadian provinces and has killed millions of trees in its wake. The insect is native to China and experts believe it was transported to the U.S. on wood packing material.

EAB has moved more quickly in other states and regions thanks to the movement of firewood, mulch and other green wood materials. A federal quarantine prohibits movement of these items outside of the quarantined area unless they are treated in certain ways to kill any insects that might be present. Anyone wishing to move hardwood firewood, mulch or ash of any kind in the counties named above (or from other infested areas) should review the quarantine requirements. Miami County will be added to the quarantine soon due to the Spring Hill discovery.

Full text of the federal EAB quarantine is available on the national EAB information site: emeraldashborer.info.

Lawrence and Douglas County has seen some loss of ash trees due to EAB infestation. Ash are popular in urban and suburban areas as well as a component of native forests. Ash are also dying in this region due to repeated years of drought, poor growing conditions (especially in cities), and stress from the feeding of native insect borers.

Determining if an ash tree is dying from EAB infestation or other factors may be difficult, but the bottom line is that if the tree is dying, remove it. Insecticide treatments work better as a preventative than a curative and even trees known to have EAB may have other environmental stressors at play.

For healthy, valuable ash trees near known infested areas, there are few insecticide options that offer protection from EAB. Anyone considering treating their trees or hiring a professional to do so should refer to the recently updated publication “Insecticide Options for Protecting Ash Trees from Emerald Ash Borer,” which is available on the EAB website referenced earlier.

Removing and replacing trees may be more cost effective than long term treatment. If space is available, go ahead and plant trees now to replace any ash that might be lost. Then, when the trees die, the replacement trees will have a head start.

Removal of live healthy ash trees is not recommended even in known infested areas. The insect moves quickly but predicting how long it will take to get to any particular tree is impossible. Already stressed trees may die very quickly while some ash can hang on to life for 10 years or more in known infested areas. Also, scientists hope that they there may be trees that show natural resistance to the pest despite the fact that it has already killed millions of ash.

Removal of ash trees and replacement with other species of trees in infested areas has cost millions. Tree nurseries and forest products industries are also suffering from the loss of this species. In some regions, forested areas were dominated by ash trees, so the loss has greatly impacted forests and wildlife.

— Jennifer Smith works in regulatory horticulture and has worked as a horticulturist for various government entities. She has experience in landscape design and maintenance and as an educator.

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