Forest pathologist’s grim outlook for tree diseases

Forest pathologist’s grim outlook for tree diseases
Robert Marra of the Connecticut Agricultural Experiment Station discusssed four tree diseases with a Norfolk audience on Saturday, July 16. 
Photo by Patrick L. Sullivan

NORFOLK — Robert Marra of the Connecticut Agricultural Experiment Station (CAES) told an audience that genetic engineering might prove a better strategy than creating hybrids in restoring American chestnuts. Marra, a forest pathologist at CAES, spoke to a group of about 50 people at Great Mountain Forest in Norfolk on Saturday, July 16.

Marra said the genetic chestnut idea is “highly contested” but could prove to be more effective than creating hybrid strains of American chestnut and blight-resistant Asian chestnut. (An example of the hybrid approach exists in a grove in Falls Village.)

Prior to widespread American chestnut blight, Marra said estimates put the percentage of American chestnut trees in hardwood forests in the eastern United States at somewhere between 30% and 50%.

The blight was caused by a parasitic fungus that was accidentally introduced into the U.S. in 1904, from imported Asian chestnut trees, which are resistant to the fungus.

By about 1950, the disease “was as widespread as the tree itself.”

Beech bark disease threatens American beeches and, to some extent, European beeches.

The villain in this case is am exotic scale insect, likely imported on European beech trees in the late 19th century.

The insect eats the bark, creating a white, waxy wooly substance.

The damage to the bark allows a native fungus to get into the tree. Marra said without the bug paving the way, the disease would not exist.

The scale insect was introduced in Nova Scotia around 1890, and Marra said the disease is widespread in the northeast and heading south at least as far as the Great Smoky Mountains National Park in North Carolina and Tennessee.

Beech leaf disease is a more recent development. Marra said it was first identified in 2012 in Ohio, and affects American, European and Oriental beech trees.

The leaves become banded, with darker areas the primary clue that the disease has struck.

Marra said foresters had no immediate answers for the disease, and that by 2019 it had spread into upstate New York, Pennsylvania, the New York City metro area, and Connecticut.

Marra showed photos of affected trees in West Rock Ridge State Park in New Haven and Hamden.

The result, he said, is trees that provide little or no canopy because of their degraded leaves.

“There’s not a lot of photosynthesis going on.”

Marra said the culprit has been identified as a nematode (aka eelworm), a plant parasite. The specific nematode here is litylenchus crenatae mccannii.

“This is confirmed and proven as causal,” Marra said firmly.

Any “wet event” (rain, drizzle, dew, or humidity) will trigger the movement and deleterious work of the nematode.

Marra wound up the grim litany of tree disease with oak wilt, first spotted in Wisconsin in 1944, and now in 21 states.

Marra said the fungus Bretziella fagacaerum grows on the oak trees, with disastrous results. The fungus is spread by oak bark beetles.

“Once it sets in it goes crazy and blocks water transport” within the tree. Marra said the result is often mistaken for effects of drought.

“All oaks are susceptible,” Marra said, red oaks most of all.

Symptoms include rapid leaf discoloration and wilting, starting at the top of the tree and moving down.

A diseased tree can die in as little as three weeks.

Is oak wilt in Connecticut?

“We don’t know,” said Marra. The CAES is collecting samples, and there was one tree in Guilford that received scrutiny.

Marra said New York state, where there is definitely oak wilt, the state has set up quarantine protocols.

But Connecticut does not have any measures in place.

Isolation and prevention measures are expensive, Marra said, showing a slide of a million-dollar piece of equipment, a vibratory plow, in use in Minnesota.

And the machine “probably wouldn’t work here,” Marra said. “Guess why?”

“Rocks!” said the audience.

 

 

 

entered 7-17 ps

edited 7-17 jc

Latest News

A scenic 32-mile loop through Litchfield County

Whenever I need to get a quick but scenic bicycle ride but don’t have time to organize a group ride that involves driving to a meeting point, I just turn right out of my driveway. That begins a 32-mile loop through some of the prettiest scenery in northern Litchfield County.

I ride south on Undermountain Road (Route 41 South) into Salisbury and turn right on Main Street (Route 44 West). If I’m meeting friends, we gather at the parking area on the west side of Salisbury Town Hall where parking is never a problem.

Keep ReadingShow less
Biking Ancramdale to Copake

This is a lovely ride that loops from Ancramdale north to Copake and back. At just over 23 miles and about 1,300 feet of elevation gain, it’s a perfect route for intermediate recreational riders and takes about two hours to complete. It’s entirely on quiet roads with little traffic, winding through rolling hills, open countryside, picturesque farms and several lakes.

Along the way, you’ll pass a couple of farmstands that are worth a quick visit. There is only one hill that might be described as steep, but it is quite short — probably less than a quarter-mile.

Keep ReadingShow less
Taking on Tanglewood

Aerial view of The Shed at Tanglewood in Lenox, Mass.

Provided

Now is the perfect time to plan ahead for symphonic music this summer at Tanglewood in Lenox, Massachusetts. Here are a few highlights from the classical programming.

Saturday, July 5: Shed Opening Night at 8 p.m. Andris Nelsons conducts the Boston Symphony Orchestra as Daniil Trifonov plays piano in an All-Rachmaninoff program. The Piano Concerto No. 3 was completed in 1909 and was written specifically to be debuted in the composer’s American tour, at another time of unrest and upheaval in Russia. Trifonev is well-equipped to take on what is considered among the most technically difficult piano pieces. This program also includes Symphonic Dances, a work encapsulating many ideas and much nostalgia.

Keep ReadingShow less
James H. Fox

SHARON — James H. Fox, resident of Sharon, passed away on May 30, 2025, at Vassar Brothers Hospital.

Born in New York, New York, to Herbert Fox and Margaret Moser, James grew up in Hastings-on-Hudson, New York. He spent his summers in Gaylordsville, Connecticut, where he developed a deep connection to the community.

Keep ReadingShow less