By Jen Llewellyn,
OMAFRA Nursery Crops Specialist

This summer the Canadian Food Inspection Agency detected several new infestations of emerald ash borer (Agrilus planipennis) in Canada and the U.S. The borer was found on ash trees in the Montérégie region of Quebec, a region that is rich in agriculture. In Ontario, it was also detected in Mississauga, Brampton, Oakville and Ottawa. These detections are having a much bigger impact on wholesale and retail tree sales in the province than those areas previously found positive for EAB. In the U.S., EAB was detected in Wisconsin and Missouri this year. There’s no question that this beetle has found a nice niche here in North America. It cannot be eradicated, but hopefully quarantines and other movement restrictions can slow its spread. Perhaps this will give nature (and science) the time it needs for predators and parasites to catch up to the beetle — before the ash trees have been completely decimated.

In the research world, scientists are busy trying to help save the ash trees. A number of researchers in Canada and the U.S. are looking at the behaviour of EAB. Multiple research groups are looking at the resistance of North American and Asian ash species to EAB and are trialing hybrid trees between the two, to help boost natural tolerance to this pest in future plantings.

Although parasites of EAB are routinely detected in North American populations of the borer, typically the parasitism rates are quite low. Collaborative research teams in Michigan are evaluating Chinese larval and egg parasites (tiny parasitic wasps) of EAB and have been working on host range studies in order to better predict environmental impacts upon their release into North America. The Michigan team released three species (EAB egg and larval parasites) last summer at three sites in Michigan. They are evaluating the effect on EAB and also on non-target impacts on other related native borers (two-lined chestnut borer, bronze birch borer) and the red headed ash borer.

Michigan scientists have also screened species of pathogenic fungi found associated with EAB populations in Michigan surveys. Isolates of Beauveria bassiana GHA and Metarhizium anisopliae were found to be pathogenic to EAB adults. Incidentally, the bioinsecticide BotoniGard also contains B. bassiana GHA and was subsequently used in some of the efficacy work (it is registered in the U.S.). They were even playing around with bioinsectide-impregnated tree bands. It was determined that this bioinsecticide does have some suppression for EAB adults and active larvae using foliar and trunk sprays.

Traditional synthetic insecticides are also being used in the battle against EAB. Injectable and trunk/foliar formulations of imidacloprid are available in the U.S. In Canada, injectable imidacloprid is not registered for use, although longer term/full registrations are being actively pursued. However, TreeAzin, a formulation of azadirachtin (or neem, a plant-based insecticide) is available for use until the end of August. The Canadian Forest Service is also looking at the efficacy of their CFS-developed formulation of neem (azadirachtin) as another injectable insecticide to help serve as a tool in our battle against this invasive borer.

Pest and disease watch for mid-September to mid-October
Growing Degree Day Accumulations (1300-1700 GDD Base 10oC)
Hammamaelis virginiana early to full bloom
Solidago canadensis late bloom
Acer saccharum early to full fall colour
 

Monitor for the following pests:

   Check out OMAFRA Publication 383, Nursery & Landscape Plant Production and IPM for more detailed monitoring tables (Chapter #3). To order, call 1-800-668-9938.
 

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Jen Llewellyn can be reached at (519) 824-4120, ext. 52671 or by e-mail at jennifer.llewellyn@ontario.ca