WINCHESTER, Va. — “None of the organic compounds work against spotted lanternfly,” said Heather Leach, spotted lanternfly Extension associate with Penn State.
Leach’s only duties at Penn State involve the growing spotted lanternfly invasion in southeastern Pennsylvania and she shared her expertise with growers in Virginia at the Tree Fruit Meeting on May 23 at the Alson H. Smith Jr. Agricultural Research and Extension Center.
“The spotted lanternfly is native to Asia and our population came from northern China in 2014, but it was probably actually introduced in 2011,” Leach said. “We have 13 counties under a state quarantine and both Delaware and New Jersey have quarantines as well. I have never worked with a pest that impacts the public most every day. The public is hyper aware of this insect in southeastern (Pennsylvania).”
The spotted lanternfly needs an actively living plant in order to feed. The pest has also invaded South Korea and caused the grape and peach industries to suffer there.
“The principle damage is the sooty mold which grows from the honey dew which is excreted by the insect,” Leach said. “There is also die back of the plants and yellowing when they are fed on by the lanternfly.”
Leach said there appears to be a reduction in cold hardiness in grapes caused by spotted lanternfly feeding.
“They are weakening the plants and then they don’t overwinter as well,” she said. “They seem to prefer grapes, black walnut, silver maple and other maples. They like to finish off the season on the maples, as it is one of the last of the trees to ready for winter, but they don’t like conifers.”
The invasive tree of heaven seems to be the preferred host for these pests.
“We have yet to know if they require the tree of heaven to lay eggs, but tree of heaven is probably not a required host,” Leach said. “It grows along the roadsides and it looks like sumac but there are two to three little knobs at the bottom of the leaves to identify them. They grow in clones, both male and female trees, but only the females produce the flowers.”
An herbicide needs to be included when removing tree of heaven “or they will come back with a vengeance,” Leach said.
Leach got her best spotted lanternfly data from vineyards.
“Three growers had substantial feeding in 2017, and in each case the vine did not die but it did not produce any fruit,” she said. “They still produced vegetatively but no clusters. We have a lot of tree fruit growers noting the lanternfly but we are not reporting any real damage. They feed for two weeks in the orchard but then they leave and we are not seeing the damage in tree fruit.”
The peak for spotted lanternfly is in late September.
The majority of the pests were spotted at the wooded edge and not in the center of the orchard. Growers should take action if they see five to 10 insects per vine, however spraying might not be able to rid the problem.
“They are constantly moving in regardless of what you spray,” Leach said. “There are a lot of complaints from harvesters as the lanternfly likes to climb on the back of your neck and on your clothes. You will find them in bins and in cold storage.”
A quarantine was just announced for Frederick County and the city of Winchester. Quarantines are also being enforced in Pennsylvania, New Jersey, Delaware and New York.
“Any business or operation in the (quarantine) zone has to have a spotted lanterfly permit,” Leach said. “It insures that every time you move the vehicle you are inspecting it. At this point there are not fines, they are just issuing warnings, but the penalty is up to $20,000.” .
Leach said that help is needed to delay and stop the spread of this pest.
The spotted lanternfly does have predators, including the praying mantis, but the predators are not able to do much due to the masses of insects.
Two natural enemies found in China are being tested in quarantine facilities to make sure they won’t cause other problems. There are also two fungi that have been found to attack spotted lanternfly, but these also need more testing.
Leach encouraged attendees to remove tree of heaven and to contact the Virginia Cooperative Extension with any spotted lanternfly sightings.