New test results show that TREE-äge trunk injections provide excellent protection for two years

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.

Data collected last week from our Adrian test site show that ash trees treated with TREE-äge trunk injections in June of 2006 at the 0.4 g ai/inch dbh rate (the Med-High rate on the product label) are still in excellent health (Table 1). Treated trees were looking very healthy (seven to 20 percent canopy thinning rating) last week while most of the control trees were dead or nearly so (90 percent canopy thinning rating).

In calendar time, we are now two months past the three-year mark following treatment, and in EAB time, we have protected trees from three generations of EAB larvae (summer and fall of 2006, 2007 and 2008). Next summer when we rate trees, we will find out if it is possible to get a fourth year of protection. We are getting very similar results from our East Lansing test wherein one treatment TREE-äge was injected in September 2005. Those trees are also still in excellent condition (canopy thinning rating of 13.8 percent). This is good news for arborists and homeowners hiring arborists to protect their trees, because each year of additional protection lowers the average annual cost of protecting ash trees. Complete treatment recommendations for TREE-äge and other insecticides that protect ash trees from emerald ash borer are available in the new 2009 Regional Extension Bulletin: “Insecticide Options for Protecting Ash Trees Against Emerald Ash Borer.” This bulletin is available on the cooperative emerald ash borer website, or from MSU Extension.

Table 1. Canopy thinning ratings (mean ± SD) of green ash test trees for three years after a single trunk injection of Emamectin benzoate (TREEäge) on June 22, 2006.

Treatment Treatment dates N 2007 Canopy thinning (%) N 2008 Canopy thinning (%) N 2009 Canopy Thinning (%)
Emamectintrunk injection0.4 g ai/inch dbh  June 2006  10  11.1 ± 6.0 A  10  12.3 ± 10.4 A1  8   7.2 ± 6.7 A
Emamectin trunk injection0.4 g ai/inch dbh  June 2006  10  11.6 ± 6.5 A   9  13.0 ± 12.7 A  8  20.0 ± 8.0 A
 Control 1 -  10  12.0 ± 15.1 A  10  58.3 ± 26.5 B  5  89.5 ± 13.4 B

1 Means followed by the same letter are not significantly different at P = 0.01 level by Tukey’s Test.

Trunk injection
Tree IV trunk injection of an ash tree.

Insecticide-treated (a) and control trees
(b,c) at BayPointe Golf Club, Orchard Lake,

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