California pot farmers wrestle with new medical marijuana rules

An unmistakeable scent, rotten-sweet and earthy, greets visitors to Basil McMahon’s pine and oak sheltered Nevada County farm.

It wafts from cannabis plants growing in a murky legal terrain between acceptance and prohibition.

Over the next few years that will change, as a sweeping new package of laws will reverse years of state silence by regulating and licensing every stage of the medical marijuana industry.

For consumers, the shift will mean more assurance that their medicine won’t be laden with pesticides and other impurities, but…