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Written By Kris Brown.

Posted on August 31st, 2021.

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In 2018, which was Year 1 of ash mortality monitoring at Siuslaw Model Forest, 15 of the 42 trees we assessed had succumbed to the emerald ash borer. As I planned to return to help with Year 4 data collection, I thought we’d have a short field day because all the ash would be dead.

In early Sept. 2018, Dr. Radka Wildova of the Ecological Research Institute (ERI) met Tracey Testo and I at Siuslaw Model Forest in Acra, NY to show us how to assess ash tree canopy health and to recognize definite and probable signs that trees were impacted by the emerald ash borer (EAB). These protocols are part of the ERI’s Monitoring and Managing Ash (MaMA) program, a citizen science effort to document EAB’s devastating impacts on ash trees in the northeast US. More importantly, this work is necessary to locate so-called lingering ash, or ash trees that remain healthy after most of the other ash trees have been killed.

In 2018, things were not looking good for ash trees at Siuslaw. For example, of the 42 trees we evaluated, 15 were already dead. By 2019, another two ash trees had died. On Aug. 10, 2021, I met Tracey and other CCE Columbia-Greene staff, including Kelsey West (Climate Change and the Environment Program Coordinator), Pammi Price (Environment and Natural Resources Program Coordinator), and Sandra Linnell (Community Horticulture Program Coordinator), to complete another round of ash tree monitoring at Siuslaw. This time, Tracey and I passed on the skills we had learned to Kelsey, Pammi, and Sandra.

We assessed canopy health:


Canopy health is assessed visually on a scale of 1 (Canopy is full and healthy) to 5 (Canopy has no leaves, although epicormic shoots may be present on the trunk). 

We examined trees for definite and probable signs of EAB infestation:


Can you spot the D-shaped EAB exit hole in the bark? This is a definite sign of EAB, one that is created when EAB larvae graduate to adults and exit the tree. What about the bark that has been stripped away by woodpeckers searching for EAB larvae? This is a probable sign of EAB.


Just under the bark, EAB larvae create unique serpentine or looping galleries when they feed. These galleries effectively girdle the ash tree causing mortality. I used a clawhammer to peel back the bark on this dead tree. Don’t do this on trees that are still alive.


This photo demonstrates epicormic shoots that come directly from the tree base or trunk instead of from branches and twigs. This is a possible sign of EAB.

We also measured tree diameter with a D-tape to assess EAB impacts on tree growth over time:

This tree measured about 10 inches (or about 25 cm) in diameter.

In 2021, we found that five more trees had died. So, of the 42 original trees evaluated in 2018, 20 are still alive. Of those 20 living trees, 12 of them (60%) show definite signs of EAB (i.e., they have D-shaped holes in the bark) and 10 of them (50%) show blonding, which is bark that has been flaked off by woodpeckers attempting to get at the EAB larvae.

On the bright side, 10 of the living trees (50%) have good canopy health and 5 of them (25%) show no sign of EAB at all after four years of monitoring. Perhaps there will be a lingering ash in the group. I also completed another round of monitoring at Lennox Model Forest in Delhi, NY on Aug. 4, 2021. I’m happy to report that there is still no sign of EAB there after four years of monitoring.   


A healthy ash tree example from Lennox Model Forest.

If you are interested in learning how to conduct these ash mortality surveys, contact the ERI for a training session. Thanks for reading.

Part 1 of this story: Monitoring and Managing Ash (MaMA) plot established at Siuslaw Model Forest to help find EAB-resistant trees.

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