Hope For The American Elm

By Mia Lanser

“Oftentimes, the things we overlook and take for granted are the things we most dearly miss when they are gone. Such is the case of the American Elm Tree. This iconic species, whose towering heights and broad canopies once lined the streets of many American cities and neighborhoods, appears to have all but been obliterated by Dutch Elm Disease. Could there still be a rare survivor that has become resistant to this devastating disease?” – rural Hollandale landowner, Tim Scott

You may remember the days when elm trees lined many streets in the state of Wisconsin. Elms were a popular pick for neighborhoods because of their fast growth, ability to tolerate urban conditions, and the beauty of their interlocking canopy. But unfortunately, since the introduction of Dutch Elm Disease the once very common street tree species has struggled in Wisconsin and other parts of the country.

According to UW Horticulture, “Dutch Elm Disease (DED) is a lethal fungal disease of native North American Elms. The fungi that cause DED entered the United States early in the 1900’s on elm logs imported from Europe. DED now occurs throughout the United States and has led to the loss of the American Elm as the premier street tree. DED is caused by two fungi, Ophiostoma ulmi and Ophiostoma novo-ulmi. Once these fungi are introduced into an area, they are moved to healthy trees by two species of elm bark beetles (one native, one of European origin).” Learn more about the science behind the disease here.

In the 1950s and 60s, DED caused a catastrophic loss of elm trees. In just one year, the city of Milwaukee lost over 16,000 trees. By the 70s and 80s, most mature elm trees were gone.

You may have heard of hybrid Asian elms, which were created through controlled breeding in North America, and are resistant to DED. It is the American Elm that has been decimated by DED.

However, not all hope is lost. The Wisconsin DNR now collects samples from living American Elms to do further testing, working with partners around the state and private landowners.

Growing up in Hollandale, Tim, has always been aware of the massive elm left standing on his mother’s property. This magnificent American Elm is over four feet in diameter and is estimated to be over two centuries old. When asked about the elm, his mother Mona, now in her 90s, stated “that big old elm has provided shade for our house for as long as I can remember”. Tim also says he, “certainly (was) not aware of just how special it may be.”

Tim told My Wisconsin Woods, “My family history in the Hollandale area dates to the settlement era when four of my ancestral lineages had claimed land for farming. In keeping with that legacy, I chose to purchase my own farm in 1995 to plant trees and develop habitat for migratory, raptor, and songbirds (and in particular, the bobolink). Starting in 1998, I began planting both conifer and deciduous tree species through the USDA – CRP program and have since planted over 40-acres of trees, many of which are towering well above 40 feet.” Tim also had a 30+ year career at the Forest Products Lab in Madison as an engineer and researcher. He is now retired.

On the Hollandale Elm tree’s health, he states, “… it is quite amazing that it has survived this long given the loss of many other elms in its vicinity and the relentless beetle attacks that have occurred over the years as evidenced by extensive galleries below the bark.”

Scientists are still trying to understand what makes an American Elm resistant to DED, and it is important to note that elm cannot be truly “immune,” but instead tolerate the pathogen itself better.

It was important to Tim to speak with an expert on the tree and its health. He told My Wisconsin Woods, “In an effort to repair the Hollandale Elm and spare it from further abuse we contacted the DNR to assess the damage and recommend possible remediation. We have subsequently had the Hollandale Elm pruned and cabled to prevent further storm damage. But what we didn’t realize was that due to its size and age, it may qualify as a rare survivor that the DNR and Forest Service have been searching for to regenerate a disease tolerant American Elm.”

Tim, My Wisconsin Woods, and the DNR are urging landowners with large elms on their property to see if they may fit the mold for a resistant American Elm tree. He reminds them “So… be mindful of what you take for granted! In this case, it may just be the key to resurrecting an iconic American tree species!”

Scott O’Donnell, Genetics and Ecology Specialist at the DNR told My Wisconsin Woods,“The WI DNR Division of Forestry is seeking reports of large survivor American Elm trees to include in Dutch Elm Disease (DED) resistance screening trials.”

The DNR is looking for any American Elm that is over 27” diameter at breast height (~7ft in circumference). Survivor elms may be resistant to DED and could be used to assist with a DED resistance breeding program at the DNR. This program aims to reestablish American Elm to its former ecological significance in the state.

Reports of survivor elms should include:

• The location of the tree including the county, locality (i.e. state forest, park, property/yard etc.) and a GPS point for the tree

• A photo of the tree, if possible

• Brief details of how to access the tree (i.e. what trail to use, in a remote area etc.)

• Contact information of the landowner if the tree is located on private lands

Reports will be reviewed and, if located on private property, landowners will be contacted to schedule a site visit. Trees that meet the above criteria will have branches and seed collected to be included in the breeding program.

It’s important to note that collections are dependent on the time of year, and early summer is the perfect time for the DNR to collect seeds. So, if you think you may have an American Elm that fits the above qualifications, you should contact the DNR.

Reports can be sent via email or phone to Scott O’Donnell, the Genetics and Ecology Specialist with the WI DNR: scottt.odonnell@wisconsin.gov or (608) 574-0859

SOURCES AND FURTHER READING

University of Wisconsin Horticulture

University of Minnesota Extension

Special thanks to Tim Scott and Scott O’Donnell for being interviewed for this article.