NEW HAVEN, Conn. (WTNH) — Scientists are working on a cure for beech leaf disease, racing to save trees that will become infected in the future.

“I have not seen a beech tree unaffected,” said Dan Poole, a licensed arborist with K&J Tree Service.

The disease is caused by a microscopic worm within the beech leaves. There’s no definitive answer to how these nematodes move around — t​he primary theory is they hitchhike on birds, squirrels and other critters that visit the beech trees.

Richard Cowles, an entomologist at the Agricultural Experiment Station, has been testing that theory by using a little bath for birds, which collects nematodes from their feet.

“That will be an indirect way of confirming that birds are acting as a vector — that nematodes are hitchhiking right on these animals,” he said.

The goal has been to not only understand how beech leaf disease is spreading, but how to treat it.

The future for beech trees has been a bleak one.

“For southern Connecticut, I think it’s a dire situation, especially in the forests,” Cowles said, who estimates “considerable mortality” in the next few years.

While the future of beech trees in our forests isn’t overly optimistic, there is some hope for landscaped ones. Cowles said homeowners can buy potassium phosphite products, which stimulate a tree’s defenses.

Phosphite has shown encouraging results in trees that are two to four inches in diameter.

“There’s an example of beech trees in New Haven that were treated last year, they have fewer symptoms than they did the year before because they were treated with the potassium phosphite treatment,” Cowles said.

The news is not as encouraging for larger trees.

“What we don’t know is the effective rate for treating larger trees than they used in that experiment,” Cowles said. “We also don’t know how much of the potassium phosphite will be carried over from one year to the next.”

However, once there’s more than 40% defoliation, trees are unlikely to recover.