ISU Extension Entomologists offer recommendations on protecting ash trees
AMES, Iowa -- The recent discovery of the emerald ash borer (EAB) in northeastern Iowa (Allamakee County) has increased interest in this exotic, invasive insect and what Iowans can do to protect ash trees (Fraxinus species) on their property. Iowa State University Extension is collaborating with Iowa state regulatory agencies and local officials to limit the spread of EAB into other areas of Iowa. For a full list of EAB detection and education activities, please visit www.extension.iastate.edu/pme/EmeraldAshBorer.html.
Treatment options to protect ash trees from this destructive pest are available, but careful and thoughtful analysis is needed to circumvent spread of false information and excessive and needless use of insecticides. Forest, horticulture and insect specialists with ISU Extension have developed a guide that outlines your management options against EAB.
The first step for many is confirming that you do have an ash tree. Only ash trees are susceptible to EAB attack; all species and varieties of ash trees are at risk. Second is determining if the ash tree is in vigorous health. Trees must be healthy and growing for treatments to be effective.
Compromised trees that have mechanical injuries, loose bark or thin canopy or are struggling to grow in poor sites with limited rooting area, compacted soil or other stresses are not worth treating. If the tree is apparently healthy and is valuable in your landscape, then preventive treatment options may be considered.
Insecticide control measures against EAB should not be used unless you live within 15 miles of the confirmed EAB infestation. Based on today’s announcement, the upper portion of Allamakee County is within this risk zone. However, due to the isolated incidence and associated remote terrain of the infested site, treatment in Iowa is still not recommended at this time.
Protecting ash trees with insecticides is a long-term commitment. Most treatments will need to be reapplied annually or twice per year for an interminable number of years to protect the tree. With that in mind, many would be ahead to remove and replace susceptible trees.
ISU Extension has a publication on the topic, PM 2084, "Emerald Ash Borer Management Options," released June 2009. The publication can be downloaded from the ISU Extension Online Store at www.extension.iastate.edu/store. The North Central Region IPM Center’s “Insecticide Options for Protecting Ash Trees from EAB” was issued May 2009 and is available on the ISU emerald ash borer website www.extension.iastate.edu/pme/EmeraldAshBorer.html.
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