An Update on Invasives, Fall 2024

by Nancy Miller, Fairfax Master Gardener
There have been two recent developments that may be of interest to Master Gardeners concerned about invasives.

The 2024 General Assembly passed an amendment that has become part of the Virginia Pesticide Control Act, §3.2-3931. This legislation directly impacts unpaid volunteers treating invasive plants on properties owned by local political subdivisions. Unpaid volunteers no longer need to be certified if using nonrestricted herbicides on invasives “with the express authorization of a local political subdivision for the sole purpose of controlling invasive plants or noxious weeds on properties owned by such local political subdivision.” The non-compensated volunteer must be directly supervised by a certified commercial applicator, and the local political subdivision must provide certain instructions. The volunteer does not need to be an employee of the certified applicator. The volunteered hours can count towards the required 40 hours to earn certification as a registered technician.

The second big announcement is that thirteen species have been added to the Virginia Invasive Plant Species List, maintained by the Virginia Department of Conservation and Recreation. While this list has no legal authority, please keep in mind that these plants cause economic and ecological harm to our landscapes. Choose your plants wisely!

Beech Leaf Disease Threatens Fairfax County Trees

by Pat Dickey, Fairfax Master Gardener
Our American Beech trees (Fagus grandifolia) are in danger of a new mysterious disease that has recently reached our parks in Fairfax County. A tiny roundworm (Litylenchus crenatae mccannii), a parasitic nematode, appears to be the culprit. Urban forest experts have been working together to determine how this nematode originally came to our country and what can be done to stop its infestation.

Beech Leaf Disease was first seen in Ohio back in 2012. Recently, in May 2022, traces of the disease were discovered in Burke Lake Park in Fairfax County. Since then, additional infestations have been found in Fountainhead Regional Park in Fairfax Station and in Hemlock Overlook Park near Clifton.

The big question is how did the nematodes come to Virginia while skipping neighboring states? Where did they originate? Right now, the thought is that the nematodes came from Asia by global commerce, on planes and ships. After they arrived, they probably were spread by wind and rain, or by insects and birds, or by all of these ways.

When the disease infests beech trees, it is easy to spot the dark bands along the veins of the leaves. You can see the disease by looking up through the tree’s canopy. The nematodes feast on the leaves and buds of the trees as a source of nutrients, and the leaves thicken and curl, turning brown and brittle.

There are around 4 million beech trees in Fairfax, and it would be devastating if they were lost to this disease. Luckily, the disease is fairly new here, and there is still time to solve its mysteries. Right now, there is no treatment to slow down the disease, but scientists are testing possible solutions. Scientists need our help in finding new areas in Fairfax where this disease has spread.

Use the app from iNaturalist to report any signs of beech leaf disease. Record observations and take several photos. Describe the area where the disease was seen so that others can determine the location.
Online webinar on Beech Leaf Disease.

Be on the Lookout for the Spotted Lanternfly

Spotted lanternfly on tree branch

A potentially very serious pest, the Spotted Lanternfly was first sighted in Frederick County, Virginia in 2018. With the growing season approaching, we need to be on the lookout for their egg masses that survived the winter cold. They can live in temperatures below 0 F. Eggs hatch in late April and early May. Nymphs have four developmental stages, or instars, and adults will appear in July.

We have included a link below from Virginia Cooperative Extension with information about their appearance at each developmental stage, where to look for them, and what to do if you see them in your landscape. Check Tree of Heaven (Ailanthus altissima), their favored host tree, and grapevines (Vitus vinifera), in particular. Contact the Fairfax Office of VCE to report any sightings.

Spotted Lanternfly in Virginia, Virginia Cooperative Extension