Land of the Lost Butternut Trees

by T'ai H. Roulston, Curator & Research Associate Professor

We're going all out this year to find Virginia's wild butternut trees, even bigger than the last time I wrote about them. It is a sharply declining tree and we are searching far and wide to find trees that might have some resistance to butternut canker, the disease killing them. Since I last wrote about this, a scientific paper came out from researchers at Purdue University who found that a few trees from West Virginia had offspring that showed intermediate levels of resistance to the disease after 13 years of growth in an Indiana orchard --not complete resistance, which has not been found yet. Still, this is very promising. The catch --even intermediate levels of resistance are rare, so the main way to find any resistance is to learn the locations of a lot of healthy looking trees in the wild and propagate their seeds in a testing orchard over years. So that's what we need to do, find lots of trees, especially healthy ones. Just this weekend someone sent me a picture of one from Grayson County with a trunk over five feet in diameter and looking healthy, and the tree is likely to become the new record holder for the biggest butternut in the state. Hopefully, it is as healthy as the trunk appears and will turn out to have good genes to pass on. Just seeing that photo gave me a sense of optimism that I seldom feel when working on declining species.

How can you help? If you know where to find wild butternut trees please contact me or my graduate student Mia Murray. We are looking to get exact tree locations, photos of trees to confirm tree identification and disease status, and leaf samples for genetic analysis. The genetic analysis is to confirm that the tree is a full native butternut, not a hybrid with Japanese walnut hybrid, which sometimes grows wild. There are 3 ways to help: 1) If the tree is on your land, take photos and a leaf sample and send them to us (we'll tell you how and provide packaging); 2) If the tree is on your land but you can't reach any leaves, send us the photos and we'll come to collect the leaf by slingshotting a line over the lowest branch and shaking off a leaf; or 3) If the leaf is on public land, take a photo and we'll get a permit for collecting the leaf sample and then come to collect it. After we get genetic samples back, we will choose the largest, healthiest looking trees to visit in the fall for collecting fruit samples to propagate. We'll be propagating the seeds here at the State Arboretum of Virginia and assess resistance over years. While we are mainly collecting seeds from healthy trees, we want to know where any trees are in the state to assess the extent of disease spread and tree survival over time.

Everything starts with simply reaching out to us with an email at uvabutternuts@virginia.edu. We'll provide all the details about getting involved, how to take the photographs and leaf samples, and anything else you want to know about the project. Thank you for helping preserve butternut for future generations.

For recognizing the tree, only the fruit is totally diagnostic on its own, but here are other main characteristics for distinguishing the species, like the leaf below, and the bark-flat and often making diamond patterns or often showing dark colored wounds from canker, like this photo below.

Learn More - Watch graduate student, Mia Murray, share a little about their butternut research, Going on a Butternut Hunt: The Quest to Save Virginia’s Remaining Butternut Trees in this youtube video.