For 30 years, Rich Colwell has been growing citrus on his Penryn orchard, Colwell Thunder Herd Ranch.
"I like to use the eye test and the taste test,” he said, grabbing a Valencia orange in hand. “If it tastes good, I’m ready to sell it to someone else."
Colwell picks his 200 mandarin, orange and lemon trees by hand and sells his harvest across the country.
“We would like it to continue to be our livelihood,” he said.
But now, the fruit of Colwell's labor is threatened by a devastating tree disease known as HLB, short for Huanglongbing.
“If the orchard gets infected, it kills the trees -- all the trees,” Colwell said. “There's no known cure."
HLB is spread by a tiny bug, the Asian citrus psyllid. It’s a menace that's been swiftly spreading closer and closer to Placer County.
“They’ve been migrating up, this particular group has come up from Mexico,” Colwell said. “It's migrating because people are moving infected trees."
Colwell and other growers are working with the state to halt the spread of the pests. Using sticky pads that attract the bugs, they are later inspected by the Department of Food and Agriculture.