Each February, I spend a couple days amongst other caretakers of Virginia forests at the annual Virginia Forest Health Professionals Conference. Each conference is a time to learn what is happening in the forests from NOVA to the southwest tip of Virginia. It was clear that 2021 canbe considered the year of the newcomer. This Nine Minute Naturalist will cover the three new diseases and pests now calling the Commonwealth of Virginia home.

Although the new introductions to Virginia are disheartening, they don’t appear to be as devastating as the emerald ash borer (EAB) or as visually disturbing as the newly introduced spotted lanternfly. The newcomers to the state are laurel wilt disease, beech leaf disease and elm zigzag sawfly. All species will have an impact on our forests but hopefully to a much lesser degree than EAB or past heavy gypsy moth infestations.

Laurel wilt disease (LWD) is a disease complex featuring a fungus and an ambrosia beetle. This disease has been creeping north from its origins in the deep south. The movement into the Scott County VA is surprising due to the primary host plant being redbay, a southern coastal plain species. The disease was found in another Lauraceae species sassafras, indicating that the fungus may be spreading via different ambrosia beetles than those feeding on redbay. LWD begins when the ambrosia beetle bores into the host tree, carrying the fungus with it. The beetle tunnels through the host leaving spores throughout the tree. Sometimes, “toothpicks” of packed sawdust will exude from the entry hole indicating beetle activity. The fungus acts very fast and death can occur within weeks. Wintergreen is home to large numbers of sassafras and spicebush, both members of the Lauraceae and thus susceptible to the fungus. The spread of LWD is not expected to happen quickly.

Beech leaf disease

Beech leaf disease is yet another attack on Wintergreen’s beech population. A walk through the Shamokin Springs Nature Preserve brings you past trees dying from beech bark disease but thankfully this disease has not affected any low elevation beech at Wintergreen. This new disease is caused by a newly recognized nematode worm. This is not particularly surprising since nematodes are the most abundant animal on earth. The symptoms begin as darkening leaf tissue between the prominent veins on the leaves. Later symptoms include leaf crinkling and curling. Tree mortality is rare amongst canopy trees but have been seen within 2-7 years in understory trees. The disease has been found in many surrounding states such as West Virginia and Pennsylvania and has only been found in one county in Virginia, Prince William County. It does not appear to spread rapidly.

Elm zigzag sawfly

The newcomer closest to Wintergreen’s boundary is the elm zigzag sawfly. This species native to east Asia was first detected on our continent in Quebec Canada in 2020 and was confirmed in Winchester, Virginia in 2021. It has been found in throughout the Shenandoah Valley including our neighboring Augusta County. This insect’s favorite host is Siberian elm, a non-native tree used in landscape environments but it also attacks other elm species. The damage is done by the larvae as they feed on leaf tissue. They got their name from the telltale patterns of eating their way through the leaf. The adult sawfly is a small, dark brown fly. While the spread has proven rapid, the affects to our environment are unknown. The population of elm at Wintergreen is quite low and is more often found in lower elevation sites.

Virginia is quite the popular place to be for many species, welcomed and unwelcomed. As spring rapidly approaches be on the lookout for our many newcomers to Virginia and send me an email at forestmanage@tnfw.org if you find something out of the ordinary.