In the back yard of an attractive beach house in Fenwick Island, Mary Ellen Langan opened a large hunting knife and began scraping at the solid branch of a pine tree.
She was looking for a blue stain among the light tan wood. That would be proof that the dead tree had suffered from an infection caused by an insect.
Some of Fenwick Island’s black pine trees have died quickly this winter, infected by a contagious microscopic nematode carried by beetles.
“These beetles and nematodes spread from tree to tree. So if you drive around town, you can see a lot of these dead and dying trees,” said Langan, head of the municipality’s Environmental Committee. “The only way to stop it is to take these trees down immediately. [Otherwise,] it’s going to spread.”
“There is no known treatment,” said Laura Yowell, a Sussex County forester for the Delaware Department of Agriculture’s Forest Service.
“Pinewood nematode lives in the wood of the infected trees. It’s transmitted by a pine sawyer beetle. Both are native pests,” she noted, which can live in native trees without causing any trouble but can also be fatal for some non-native trees.
First, beetles find and feed on the weakened trees. They carry the nematode, which gets under tree. About 95 percent of the time, people can see the blue stains indicating a fungus the nematodes carry.
“You have to cut into a limb. If you see a blue stain under the bark, there’s evidence there’s a nematode,” Langan said.
The dead and rusted branches will stand out among the springtime greenery.
“If you have a black pine, if it went from alive to dead in a very short amount of time, this is what it is,” Yowell said. “It’s a tough one to fight. It really is.”
“These trees need to come down,” Langan has been saying all winter.
Officially, the only way to diagnose these trees is through the University of Delaware lab, but Yowell said that’s hardly necessary, “because any black pine that suddenly dies is probably this.”
Only non-native pines are being affected by this sudden wilting, browning and death.
However, those symptoms shouldn’t be confused with regular windburn, which Yowell described as the sudden browning of needles that clears up after a few months.
Keep ’em safe
Trees are considered valuable at the beach. They anchor the sand, block wind, protect houses from storms, buffer noise and generally add depth in a town where houses often fill almost the entire lot.
But, ultimately, black pines are a non-native species, and they can’t withstand the Delaware insects.
“They were planted here because they do pretty well in the poor soils that you have, and they grow really well,” Yowell explained.
The native loblolly pine is more resilient against pine wilt, she noted.
But prevention is possible. Black pines are vulnerable when stressed (and they’re always stressed in a sandy saltwater environment), so they need some love to stay healthy. They can be watered during dry spells, and people can avoid damaging their roots when digging nearby.
If the infection strikes, however… “It must be removed and completely destroyed. … You can’t just cut it down and leave it,” Yowell said.
The bugs will still infect a downed log, so the wood must be completely destroyed, by chipping, mulching or burning. But the stump and roots can remain behind.
“A lot of people are taking them down, which is great,” Langan said during a May tour of the town.
Langan had estimated about 30 sick trees in town, though it’s hard to tell without trespassing on private property. But once a person starts looking for dead trees, they’re easier to spot.
Where possible, the Environmental Committee has already contacted some people, encouraging them to remove infected trees on their lots. Of course, committee volunteers are limited to the trees they can see from the road.
In her effort to educate, Langan has gotten both support and the stink-eye. Removing trees isn’t exactly cheap and easy, but it will save the others.
“If your neighbor has a dead tree on their property, would you please tell them to remove it?” she suggested. “Otherwise, it’s going to kill all the other trees in the vicinity.”
“As soon as the weather started improving, people start coming down” for spring maintenance, Langan said. “We want to educate the public about this problem and let them know, if they have an infected tree, all of trees on the property could be affected, too.”
And their neighbors’ trees.
“The pines look nice, but they also have a role to play in this community,” Councilwoman Julie Lee said after Yowell’s talk. “Better to take them down than to have the whole town devoid of pine trees.”
“They’re very important to the town because they protect the town. It’s important that we save them,” Langan said.
Anyone with questions can contact Fenwick Island Town Hall staff, who will pass the message to Langan.