Spraying not recommended for EAB control

Homeowners and green industry professionals concerned about emerald ash borer (EAB) should think twice before deciding to spray their trees, as insecticide applications will not save their ash if the wood-boring pest is found in neighbouring trees and eradication in the area is required. In an insecticide recommendation issued this week, experts with Ohio State University Extension’s Nursery, Landscape and Turf Team state that: “Currently, we do not recommend that any ash trees be treated with insecticides for emerald ash borer, even if the tree is in the immediate vicinity of a known infestation.”

The recommendation was drafted in consultation with the Ohio Department of Agriculture (ODA), based on the interaction between the insect’s biology and regulatory issues associated with the program to eliminate EAB from North America, an effort led by the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service.

All ash trees in the vicinity of a confirmed infestation must be destroyed, even if they have been treated with insecticide following eradication protocols. This is done to keep larvae that may be hatching in any of those trees from maturing and spreading even farther. Research has shown that no insecticide is 100 per cent effective against EAB. The same recommendation applies to people who own ash trees near known EAB infestations. Thus far, EAB has been positively identified in Lucas, Defiance, Paulding and Wood counties in Ohio, and has spread to Ontario and Maryland.

ODA has already implemented an eradication program in Whitehouse, Lucas County, where the pest was first identified in Ohio on February 28. There, about 8,000 ash trees within a quarter mile of the five properties infested were cut, chipped and incinerated. Similar eradication efforts will take place in the other counties before emergence of adult beetles next spring.

People near an eradication zone may be tempted to treat their trees as insurance in case EAB escapes the eradication program. However, if a beetle survives eradication it is extremely unlikely that it will lay eggs only on trees that have been sprayed.
“If the beetle does lay eggs, even on only one untreated tree in the same neighborhood as the treated ones, eventually the untreated tree will show signs of infestation and will have to be destroyed,” explains Dan Herms, an entomologist with the Ohio Agricultural Research and Development Center (OARDC) and a member of the Ohio EAB Task Force. “In this case, all trees in the vicinity of the infested tree will have to be destroyed, even if they have been treated.”

For more information about EAB, contact your local CFIA office.

Information provided by Ohio State University Extension. There is currently no insecticide registered for use in Canada for EAB.