Ash or Look Alike
Due to the impending infestation of Emerald Ash Borer (Agrilus planipennis) it is very important to get an accurate inventory of ash trees (Fraxinus spp)across the state. Emerald ash borer is a green beetle that feeds on ash trees during its larval stage eventually killing the tree. It has been spreading across the country from southern Michigan, and is present in eastern Pennsylvania, New York, and Maryland. As of May 2014, emerald ash borer was positively identified in Somerset County, Mercer County, and Burlington County NJ.. By having an inventory of ash trees it is possible to make plans for the maintenance of ash trees as they become infected and need to be removed. Knowing where ash trees are present is important to allow for proper planning on replacing those trees that need to be removed.
To complete an inventory of the ash trees in your municipality you will need to be able to correctly identify ash trees, which can be tricky because they can look like several other trees that are frequently growing in the region. There are 3 species of ash that are native to parts of the state, white ash (Fraxinus americana), green ash (Fraxinus pennsylvanica), and to a lesser extent black ash (Fraxinus nigra). All native species of ash have compound leaves with an odd number of leaflets from 5 to 11 arranged oppositely on the branches. Green and white ash both have brown to gray bark with corky interlacing ridges that form a diamond pattern, while the bark of black ash is smooth when young and gets scaly with age.
Many other trees can have a similar appearance to ash at a quick glance but if you take the whole tree into consideration you can differentiate them. If you are only looking at the leaves of a tree the most likely mistake you would make would be calling an ash a box elder (Acer negundo), or vice versa because they are the only other common tree that has both opposite and compound leaves.
Other trees that could be mistaken at first glance include black walnut (Juglans nigra), summac (Rhus spp), tree of heaven (Ailanthus altisima), and hickory (Carya spp.).