"They say money doesn't grow on trees," the arborist notes in the episode. "But for me it does."

His current business, " We Love Trees ," was founded in 2007. It became so successful that it landed him an appearance on CNBC's " Blue Collar Millionaires ."

Years later, after he graduated college, the problem still hadn't gone away, so Long decided to do something about it. He'd gone to college "without any type of direction other than to get a job and make money," he tells CNBC Make It . But he ditched his white-collar career path and decided to become a "tree doctor."

When he was just a boy, the deadly disease Oak Wilt rampaged through his Austin, Texas neighborhood, strangling and ultimately destroying trees.

For Jon Long to come up with his million-dollar idea, he had to draw inspiration from his roots.

Long started by reading as much as he could on the spread of Oak Wilt. His first business, Oak Wilt Specialist of America, was founded in 1998 and took off after he invested a total of $110,000 of his own money in the materials he needed to inject the trees with a fungicide called Alamo. When he bought his high-powered rock saw, he borrowed another $9,000 from his wife Paula.

The investment paid off. After two years and after a lot of trial and error, Long says he made all that money back.

As Long explains to CNBC Make It, there are four steps to his process, all of which can be completed in a single day. First, he and his two employees cut a trench around the tree deep into the ground with heavy machinery to suppress the disease's spread. Next, they inject the trunk and roots with fungicide. Then they remove the dead trees and replant more.

Typically, the cost to the customer for all of that comes out to just over $10,000. "So if you do all four protocols on a day," he says, "You're really having a great day." But often, he'll spend one day trenching and injecting, and the next removing and replanting.

Nonetheless, the tree doctor's profit margins are better than some actual doctors'. As "Blue Collar Millionaires" points out, "While the average physician's office nets about 10 percent, Dr. Long can make four times that — on a bad day."

Long is the first in the area around Wimberly, Texas to offer the service in such a comprehensive way. "Prior to us coming into the market, Oak Wilt trenching was done by utility contractors that knew less about Oak Wilt than, normally, the home owners did," he says. "And the tree injectors were primarily arborists."

"We married the two disciplines," he explains. "We married an arborist profession and a utility contractor profession."

And because of the materials he had, including his rock saw that he uses for the trenching, he was able to provide a more efficient and much cheaper service than others for the customers, who are usually large-ranch owners investing a lot of money to save their trees.