New insecticide products are providing excellent and affordable protection of ash trees from EAB

Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.      

We have just finished compiling our ratings of ash trees in East Lansing and Adrian, Michigan where we have been treating large, 12 to 15 inch dbh, ash trees to protect them from emerald ash borer as part of a research test on several new products. The canopy ratings of test trees this summer marks the third year since the test began. The control trees at both sites have declined dramatically during the test, going from an initial rating of 10 percent in 2005 to 50 to 65 percent canopy thinning and dieback in 2008.

The rating scale used to estimate canopy thinning and dieback is posted in this issue so you can see exactly what 10, 30 or 50 percent canopy thinning means. Several products gave excellent protection against emerald ash borer in these tests. A single TreeÄge trunk injection in the fall of 2005 provided excellent protection for three years, with a canopy thinning rating of 19.3 percent in August 2008. Other treatments giving excellent protection of 12 inches dbh trees in East Lansing are ImaJet trunk injections once every two years (23.5 percent), and Merit basal soil drenches once per year (18.0 percent).

Getting good protection of the larger street trees in Adrian was more difficult, but several products also worked well including: TreeÄge once every 2.5 years (12.3 percent), ImaJet trunk injection plus Merit basal soil drench once per year (13.5 percent), ImaJet alone in June 2007 (29.7 percent), Merit basal soil drench once per year (33.0 percent), and Merit Tree trunk injection in June 2007 (34.2 percent). The average rating of control trees was 64 percent. Tables of results are included in this Landscape Alert issue. A more complete report will be posted on http://www.emeraldashborer.info in October.

Ash protection in East Lansing, Michigan 2005 – 2008 (mean dbh = 12.0 inches)

Treament Date n Canopy thinning August 2008
TreeAge September 27, 2005 10 19.3
TreeAge September 27, 2005, May 21, 2008 10 14.5
ImaJet September 27, 2005, May 21, 2008 10 23.5
Arena soil drench (clothianidin) November 8, 2005 10 18.5
Merit 75 soil drench June 2006, June 2007 10 18.0
Safari soil drench May 18, 2007, June 10, 2008 9 27.5
Control   10 51.3


Ash protection in Adrian, Michigan 2006 – 2008 (Mean dbh = 15 inches)

Treatment Date N Canopy thinning August 2008
TreeAge June 2006 10 12.3
TreeAge June 2006 10 13.0
ImaJet 0.4 + Merit soil June 2007, June 2008 10 13.5
ImaJet 0.4 June 2007 9 29.7
Merit drench June 2006, 2007, 2008 10 33.0
Merit Tree 0.4 June 2007 9 34.2
Imajet 0.4 June 2006 11 45.0
Xytect soil drench Fall 2006, Spring 2007, Spring 2008 10 52.0
Control   10 64.0

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