A Colorado rancher in his 80s who waged war on mosquitoes by spraying pesticides that wafted over his neighbors’ organic farm has been ordered to jail after months of fighting his conviction.

The Colorado Court of Appeals on Thursday affirmed a ruling that James Hopper must serve two days in jail and pay a $7,500 fine for spraying on his land in Delta County in violation of a 2012 court order protecting his neighbors.

The decision bolsters a legal precedent that wafting pesticides can constitute a trespass against which adjacent landowners and people with health sensitivities are protected.

Hopper’s neighbors, vegetable growers Rosemary Bilchak, 62, and Gordon MacAlpine, 72, who has leukemia, welcomed the decision. “This justice has been a long time coming,” Bilchak said.

Hopper couldn’t be reached. He has said he was motivated to eradicate mosquitoes after his wife nearly died from West Nile virus. Hopper took a state exam and received, in June 2011, a Colorado pesticide applicator’s license. He then obtained a London Fogger, a device with a funnel that he mounted on the back of a pickup. He filled it with Fyfanon, a pesticide containing malathion, and sprayed it out to eradicate mosquitoes, court records show.

But the pesticides floated in the air onto the adjacent 20-acre property that Hopper sold in 2005 to Bilchak and MacAlpine, farmers who wanted to expand their organic vegetable production.

In 2012, District Court Judge Charles Greenacre ruled that the Hoppers have a right to protect themselves from West Nile virus but that their neighbors have a right not to have their property invaded by other people or things. He ordered Hopper to control his use of pesticides.

Hopper kept spraying. Court records show he continued through August 2015. State Judge Jeff Heron last year sentenced him to jail and imposed the find for violating a court order. And the appeals court judges on Thursday backed up that finding that Hopper willfully violated the order.

“This is very important to us,” Bilchak said. MacAlpine, diagnosed with leukemia before moving to Colorado, had been told by his doctor to avoid pesticide exposure and was registered with the Colorado Department of Agriculture as a sensitive resident. “It is important for us personally, for his health condition and because we also set a precedent that pesticide drift is a trespass,” she said.

Pesticide disputes typically are settled by state agricultural authorities who oversee use of chemicals. Minnesota’s Supreme Court in 2012 looked at the issue, and the judges ruled pesticide drift is not the same as a trespass.

The U.S. Environmental Protection Agency has relied on product labeling to protect people from harmful pesticides.

“This case sets a level of protection for Coloradans who care about their private property and for organic farmers who need to keep their property safe from pesticide exposure,” said Boulder-based attorney Randall Weiner, who handled the case.

“No one is exempt from the responsibility to comply with court orders. This spraying had gone on for seven years, and an individual was caught red-handed,” Weiner said.

“The underlying decision, which the courts forcefully have affirmed, is that pesticide spraying can constitute a trespass on private property, organic farmers and people whose health is precarious.”