School field trips often make a pilgrimage to Basking Ridge Presbyterian Church in New Jersey, specifically to the church cemetery where the towering great oak tree stands. The children join hands and surround the massive trunk to see how many of them it takes to circle the historic tree.

More than 100 feet tall, the majestic white oak is thought to be more than 600 years old. It is believed to be the oldest white oak in the country, and perhaps the world. The tree has withstood war and natural disasters, including Hurricane Sandy. George Washington is said to have picnicked under its branches and rested there with his troops on several occasions. Wedding parties often pose for photos by the tree. Visitors stroll through the cemetery grounds, shaded by the oak's branches, which spread more than 150 feet side to side.

But church administrators have known for several years that something has been amiss with the historic oak. It hasn't been greening up the same way each spring, and even with the help of an arborist who has cared for the tree with fertilizer, leaf spray, PH control, watering, pruning and upkeep of the oak's extensive system of cables and limb supports, its health has been declining.

"This program has no doubt helped extend the life of the tree, but it has not been able to reverse the inevitable aging process that faces all living things," church pastor Dennis Jones wrote in a letter to his congregation. "The aging of our oak tree has accelerated over the past 10 to 15 years, culminating in its current condition coming out of the past winter."

Basking Ridge oak tree and church on old postcard The tree was a little younger on this postcard from some time before 1923. (Photo: Presbyterian Historical Society/Wikimedia Commons)

Soil samples and cuttings have been sent away to experts at Rutgers University, church administrator Janet Bentley tells MNN. People in the community and from much farther away are weighing in with calls and letters, offering their concern and suggestions. ("You've overlimed it!" or "That tree desperately needs lime!")

For a community that has been defined by the tree’s presence, with oak leaves on every logo connected to the area, the fate of the behemoth weighs heavily.

"We absolutely don't think the impact the tree has on the community could be understated. It's just been a part of the fabric of the community since day one," says Bentley. "People are so worried about it. The tree is a symbol of strength. It's a treasure and our hearts are broken that she's not doing well."

Experts aren't sure why the tree is failing to thrive. Jones told the Washington Post that he believes it is simply old age. White oaks typically live between 200 and 300 years and the Basking Ridge oak has long surpassed that.

There is talk about trimming dead branches and doing whatever possible to keep the tree standing, but Jones talks to the Post as if talking about an ailing loved one.

"It's about knowing when to let go," Jones said. "We want to treat the tree with respect and not prolong its death."

Mary Jo DiLonardo Mary Jo writes about everything from health to parenting — and anything that helps explain why her dog does what he does.