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In major policy shift, Massachusetts clears marijuana growers to use certain pesticides

Cannabis industry says change will improve pot quality by helping cultivators fight mold and pests

Suehiko Ono, cofounder of marijuana firm Eos Farm, poses for a portrait in Pittsfield in 2019.Nathan Klima for The Boston Globe

Licensed marijuana growers in Massachusetts will now be allowed to apply certain pesticides to their crops, after state agricultural officials repealed a longstanding ban on the practice that the cannabis industry had long derided as unnecessarily strict.

Under a Nov. 30 edict from the Massachusetts Department of Agricultural Resources (MDAR), which has jurisdiction over pesticide use at marijuana facilities, cannabis cultivators gained permission to deploy a wide range of mostly natural chemicals that are federally approved as safe for use on hemp and tobacco. They include beneficial bacteria that kill leaf-munching worms, fertilizers and fungicides commonly used to produce organic food, and synthetic hormones used to grow new plants from clipped branches.


“MDAR recognizes that the industry has been in need of tools to help combat pest problems,” a spokeswoman for the agency said in a short statement. “By updating the pesticide policy and adding additional precautionary measures, the new criteria will provide the industry with new tools to protect their crops while still ensuring current laws and safety measures are complied with.”

The new rule replaces an antipesticide policy that growers said was one of the most stringent of any US state with legal cannabis. Previously, MDAR permitted growers to use only a short list of concentrated plant oils, mild detergents, and basic compounds designated by the federal Environmental Protection Agency as posing a “minimal risk” to health.

Massachusetts cultivators had complained for years that those pesticides were ineffective for large-scale operations, especially outdoors, leaving them with few options to prevent and eradicate mold, pests, and other blights affecting their crops. The result of the old policy, they said, was substantial crop loss and lower-quality pot.

Now, commercial growers are ecstatic over the expanded list of allowed pesticides, saying it will help reduce costs without endangering the health of cannabis consumers.


“It’s a huge step in the right direction,” said Suehiko Ono, the cofounder of the Eos Farm outdoor marijuana growing facility in Pittsfield. “Now, our only recourse for mold and pests isn’t walking counterclockwise around the plants during a full moon holding a butterfly wing — we can actually use science and chemistry and biology.”

Ono, who said he lost 60 percent of his 2021 harvest to worm damage, estimated the change in regulations could halve the amount of crop losses for both marijuana and hemp cultivators. Growers are already facing a squeeze brought on by plunging marijuana prices.

Officials at MDAR said the decision to allow pesticides on pot was made possible in part by the federal government’s 2018 legalization of hemp — a variety of cannabis with almost none of the THC that causes marijuana’s distinctive high — which prompted the EPA to begin approving various pesticides for use on hemp. Officials at MDAR said that because the only distinction between the two plants “is a legal one,” they have decided to allow many of the same compounds to be used on Massachusetts marijuana crops.

In addition to being approved for use on both hemp and tobacco, pesticides under the new MDAR policy must also meet several other criteria to qualify for use on marijuana. While the agency said it will not maintain a list of approved compounds, it has circulated a flow chart meant to help growers verify that a given product is permitted.


Even with those limitations, growers said they’re hopeful the regulatory change will allow them to save money by applying more effective preventative compounds less frequently, while also providing them with more options to suppress pests and microbes that manage to evade those controls. In turn, that should reduce the need for cultivation facilities to employ “remediation” techniques to destroy microbes, such as radiation treatments that rely on pricy equipment and hydrogen peroxide baths that can over-dry flower and reduce its quality.

They also said the use of hormone gels will drastically increase the percentage of clippings from a “mother plant” with desirable traits that successfully take root, making it faster, cheaper, and easier to sow a new crop. Meanwhile, the greater variety of fertilizers now available should help boost the amount of usable marijuana yielded by each plant.

“It’s a boost across the board,” said John Snyder, the chief operating officer of 253 Farmacy in Turners Falls. “These are the safest products you can use, and they’ll really help keep people in business. With the market being as competitive as it is, you’ll take anything you can get.”

Several Massachusetts marijuana firms have been sanctioned in recent years by state regulators for using banned pesticides.

In 2018, the Department of Public Health temporarily shuttered operators Good Chemistry and Triple M for using common compounds the companies insisted were natural and safe; Triple M later paid the state $50,000 for allegedly misleading officials about the incident.


Strict enforcement continued after the Cannabis Control Commission assumed oversight of medical and recreational marijuana in late 2018. The agency in 2020 reached a $200,000 settlement with Garden Remedies after inspectors caught the company using rooting gel at its Fitchburg growing facility and falsifying records to disguise its purchase. At the same time, the commission slapped Mission — owned by interstate conglomerate 4Front Ventures — with a $350,000 fine for repeated violations of the pesticide ban.

Growers expect the new rule from MDAR will reduce the likelihood of such sanctions, though a large number of synthetic pesticides remain banned.

In a brief statement, the commission said it would continue to collaborate with agricultural officials on pesticide enforcement “to protect public health and safety and ensure all state laws and regulations are being complied with.”

Dan Adams can be reached at Follow him on Twitter @Dan_Adams86.