The marijuana industry has a pesticide problem.

Many commercial cannabis growers use chemicals to control bugs and mold. But because of the plant’s unresolved legal status, Colorado regulators are having a tough time making sure pot buyers don’t ingest those pesticides. The parts of the federal government that regulate agricultural pesticide use want nothing to do with legalized marijuana.

“In the absence of any direction, the subject of pesticide use on the crop has just devolved to just whatever people think is working or whatever they think is appropriate,” says Colorado State University entomologist Whitney Cranshaw.

Luke Runyon / KUNC and Harvest Public Media

Tobacco farmers, for example, have a stable of pesticides the federal government says is safe to use. But no pesticide in the U.S. has been approved for use on cannabis.

“Sometimes [marijuana growers] have used some things that are inappropriate, sometimes unsafe,” Cranshaw says.

Educating farmers who grow different types of crops about safe pesticide use is part of Cranshaw’s job at CSU. He’s an extension agent, specializing in integrated pest management. But if a recreational or medical marijuana grower asks him for advice, he has to turn them away, or help them when he’s not on the clock for the university. Otherwise he could be fired.

“CSU extension agents may not assist cultivators of marijuana,” reads a Colorado State University legal counsel memo distributed to staff in November 2014. “Extension agents are prohibited from physically visiting hemp or marijuana growth facilities [or] fields not owned by the university as part of their CSU employment as they risk arrest by the [Drug Enforcement Administration].”

In one grow room at Medical MJ Supply in Fort Collins, Colorado you’ll find all the trappings of a modern marijuana cultivation facility: glowing yellow lights, plastic irrigation tubes, and rows of knee-high cannabis plants. The plants are vibrantly green and healthy. Owner Nick Dice says that’s because the company’s taken a hard line on cleanliness.

“We have people who that’s their only job is to look for any infections or anything that could cause potential damage to the crop,” Dice says.

"In the absence of any direction, the subject of pesticide use on the crop has just devolved to just whatever people think is working or whatever they think is appropriate."

As any farmer will tell you, damage to the crop equals damage to the bottom line. Medical MJ Supply’s multiple grow rooms have never seen widespread pestilence. But before he started an intense disinfectant routine, using the same cleaner found in many Ebola wards, his team of growers sprayed a regimen of mild chemicals to keep cannabis pests under control.

“We would switch between multiple pesticides and mildew treatments, and we would try to treat anywhere from every three to four days, honestly,” Dice says.

Some of his fellow growers in the industry have had operations crumble as their cannabis succumbs to an outbreak of powdery mildew, which coats the plant’s leaves. Or fall victim to two-spot spider mites that feast on its stems, and reproduce like crazy. Pest controls ensure a good yield. And when it comes to cannabis, yields matter. One room at Dice’s business houses $180,000 worth of plants.

Dice’s grow facility recently implemented biosecurity protocols, like asking growers to change clothes before entering grow sites, and wash hands to prevent cross-contamination from another garden. More growers are clamping down on cleanliness, says Brett Eaton, director of horticulture at Denver-based consulting group American Cannabis Company.

Protecting a crop yield is hard work. That’s why many growers use chemicals, Eaton says. To safely use them, and avoid running afoul of fast-changing state rules, private consulting groups have begun to fill the void.

“Anybody can get their hands on harmful chemicals, and they can just spray away up until the last day of harvest,” Eaton says. “What is that doing to the product? And to the consumer who is consuming that product?”

The state of Colorado doesn't require growers submit to lab tests to detect traces of pesticides left on the crop. A statewide mandatory testing program for marijuana is only partially up and running, with required tests for potency, but not other contaminants. Colorado’s Marijuana Enforcement Division is currently beta-testing a program with licensed marijuana laboratories to measure potentially harmful residual solvents, like propane and benzene, in marijuana-based concentrates. Mandatory tests for residual solvents could be in effect before the end of the summer, according to a division spokesperson.

Public health concerns led Denver officials to place a hold on tens of thousands of marijuana plants in the spring of 2015. City officials issued a bulletin to remind growers of laws regarding indoor pesticide use. An investigation is currently underway. Ultimately, pesticide enforcement is up to state agriculture officials, who took more than a year to release a list of pesticides deemed benign enough to use on cannabis. Washington state and Illinois have similar lists.

“Other agricultural industries already have policy in place for the safe use of spraying certain pesticides and fungicides,” Eaton says. “This being a new industry, it just hasn’t been addressed yet.”

As marijuana use and cultivation becomes more mainstream, this is one issue regulators will have to address, Eaton says. More states are likely to turn marijuana into a commodity crop in 2016. To keep consumers and marijuana grow site workers safe, Eaton says, it’ll take a mix of policy, science and industry self-regulation to figure out what’s appropriate, and what’s not.

Correction: A previous version of this story inaccurately detailed the Colorado Marijuana Enforcement Division’s cannabis testing requirements. Mandatory tests for residual solvents are currently in the beta-testing phase, with full implementation later this year. There is no timeline to implement required tests for pesticide residues.