Large numbers of Minnesota doctors say they won’t sign their patients up for medical marijuana.

Two-thirds of physicians who responded to a Minnesota Medical Association survey this week said they will not participate in the state’s medical cannabis registry. Just 9 percent of respondents said they would be certifying patients.

Medical marijuana will be legal — in limited form — in Minnesota on July 1, but to participate in the program, patients must be certified by a doctor or other medical professional to prove they have one of nine qualifying conditions.

Doctors can opt out of certification, and some already have. When Shelly Rapp of Chanhassen asked her neurologist to certify her 18-year-old son Scott, who uses a wheelchair because of epilepsy, she was told that while he was willing, his practice as a whole had opted out of the Health Department program.

“He called me today, and was really nice, but said he was unable to help,” she said.

Scott had tried medical cannabis while the family was living in California last year, and Rapp said a few drops of the oil a day not only cut his seizures from hundreds a day to just a handful, but allowed him to wean off his other seizure drugs. She’s eager to get him back on cannabis oil, but first she needs to find a doctor, nurse or clinic willing to certify to the state’s Office of Medical Cannabis that Scott has epilepsy.

Marijuana plants are being grown to supply the state’s new medical cannabis program. Enrollment in the program got off to a slow start this week, and a Minnesota Medical Association survey showed that a large number of doctors do not plan to participate.

Next, she tried her family doctor.

“He said he was going to think about it, but I kind of doubt he will,” Rapp said.

The Minnesota Medical Association (MMA) survey found that 68 percent of doctors who responded to the June 2 survey were not planning to participate in the program.

Of 457 physicians who responded quickly, just 9 percent said they would be certifying patients, and 17 percent hadn’t made up their minds. Another 7 percent treat patients who are not eligible for the medical cannabis program.

The highly negative response, from a small sample of all Minnesota doctors, caught MMA president-elect Dr. David Thorson off-guard. He thinks the results reflect doctors wary of a system that has largely sidelined physicians, while pharmacists dispense a drug that is still illegal at the federal level — and is backed by very little clinical research.

“That’s alarming to me. It shows that access is going to be an issue,” said Thorson, who does plan to register with the Office of Medical Cannabis, eventually. “I understand why people say they won’t certify. I don’t think it’s anything malicious. I think it’s just saying, ‘Based on my knowledge, I don’t see a value to doing this.’ ”

Some medical practices are wary of attracting too many patients simply in search of cannabis certification. Some have more questions about the drug’s efficacy or possible side-effects.

Dr. Dean Gesme, president of Minnesota Oncology, a practice of 60 oncologists and 25 nurse practitioners and physician assistants, says he doesn’t know that any of his physicians are “militantly” against the law and the use of medical cannabis by patients.

However, Gesme said that many are concerned about the unfunded mandate that will fall in their laps — the time it will take to counsel patients about an unfamiliar drug that state law bans them from prescribing.

“The patient who wants marijuana would come in and we can fairly simply certify them,” he said. “But they will want us to tell them how to use it, when to use it, which type is better, where should they go to get it. … It’s just another issue that is kind of dumped in our lap.”

Assistant Health Commissioner Manny Munson-Regala, who is overseeing the rollout of Minnesota’s medical cannabis program, noted that enrollment had been open only for a few days. The state and the MMA are working to answer doctors’ questions about how the program will work.

Enrollment for the new medical cannabis program got off to a slow start on Monday. By the end of the first day, 30 physicians had registered with the state, and the Office of Medical Cannabis had registered its first patient.

The medical association survey went out to more than 14,000 physicians across the state. About 9 percent of the responses were from doctors with practices that would have the highest number of patients eligible to participate in the program — 3 percent each for neurologists, ophthalmologists and oncologists.

Thorson said the medical association is planning a more detailed survey later this month to delve into why so many physicians are responding negatively to the program.

Staff writer Jeremy Olson contributed to this report.