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Branch sampling

Use this method to detect the presence of emerald ash borer (EAB) in trees without symptoms, or to detect the presence of EAB in an area. This method can be extended to estimate the density of EAB in the sampled tree, which may give an indication of whether it is a good candidate for treatment.

This method is successful for detecting EAB infestation in asymptomatic urban ash trees in 74% of cases[40,41]. The efficacy of this method in woodlots and parks, or in trees or branches smaller or larger than those recommended is unknown, however, it can still be tried. This approach can be time consuming especially if assessing the level of infestation.

On an open-grown tree of 15-50 cm diameter at breast height, select two live branches that are 5-7 cm diameter at the base[41]. The branches can be from any level of the crown, but should be taken from the south side of the tree[52]. Cut each branch at its base and then cut off the bottom 75 cm. Secure the 75 cm branch section in a vice and carefully peel back bark in thin layers looking for EAB galleries and/or larvae in the bottom 50 cm of the branch. If the objective of the branch sampling is to confirm the presence of EAB, peeling can stop after the first gallery is detected. If the objective is to quantify EAB, then each gallery in the 50 cm section of the sample must be counted. Sampling longer branch sections, or more than one section per branch will increase the accuracy of this method[52]. Branch sampling is best conducted after October when EAB galleries are easier to see[41].

Read the full details of the the branch sampling method.

Watch a branch sampling demonstration.

EAB gallery in branch
EAB gallery in branch. Image: Chris Gynan, Silv-Econ Ltd.

EAB positive tree?:
If you think you have found EAB galleries or larvae in a tree outside of the areas regulated for EAB, contact the CFIA at 1-866-463-6017.


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