Fighting destructive tree disease
First discovered in Ohio in 2012, Beech Leaf Disease (BLD) has since spread to numerous northeastern states. BLD appeared in Suffolk County in 2019, and it now affects American and European beeches on Shelter Island.
Among Shelter Island’s abundance of iconic tree species, our American and European beeches stand out for their impressive size, splendid canopy and handsome, gray bark.
As we discovered when it appeared on the Island last spring, BLD is in Mashomack and Dering Harbor, and there’s evidence of it in one of the Town preserves. It’s also, unfortunately, hit a magnificent tree at the entrance to the cemetery.
The disease is caused by a non-native, microscopic worm called a nematode. The nematode settles into the winter leaf buds and then moves into the unfurling spring leaves, damaging leaf tissue, which impedes photosynthesis.
Deprived of nutrients, a weakened tree can die within 6 to 10 years. Afflicted trees first exhibit distinctive banding on the leaves. In subsequent seasons, leaves show more banding along with crinkled, dead leaves on the ends of branches.
Aside from their magisterial beauty, beech species such as the American beech provide benefits to numerous animals.
There is no cure. However, among ongoing experimental treatments, the most promising appears to be a fungicide/nematicide called Broadform that’s applied as a spray in the spring after the leaves have emerged.
According to Margery Daughtrey, Cornell Senior Extension Associate, it can only be applied by a licensed arborist and they will need a Special Local Needs permit. (Homeowners should research Broadform before it’s used on their property.)
The treatment is only labeled for ornamental specimens. Groves of beeches in woods and forests will have to wait for other methods such as natural biological controls. Healthy trees can be treated with a springtime application of fertilizer or compost.
They should also be watered during hot, droughty periods.
In a recent article in Suffolk County Agricultural News, Ms. Daughtrey writes that while “none of the treatments now being tested is guaranteed to help,” she recommends “staying in touch with the current research …so that [we] can take advantage of any discoveries that open up.”
She also asks for patience. “Our inability to solve this problem with a few sprays will cause some frustration to arborists’ clients. But this is a scientific frontier, and we just don’t have all the answers yet.”
Let’s keep our fingers crossed.
Tim Purtell, President of Shelter Island Friends of Trees, can be reached at [email protected]
