graciela carreno chose to drop denomination of origin two years ago.he crop does not grow back each year. >> translator: you can only benefit from it once in its lifetime, and it takes 30 years to give you its best. >> if mezcaleros obsess over their agave, it's because they're trying to avoid repeating tequila's mistakes. overplanting of blue agave used in tequila has rendered that plant more susceptible to disease. carreno says she worries the same could happen to mezcal's workhorse variety, espadin. >> translator: it's like tequila, only with mezcal we plant espadin. only espadin. the irony is on the world market what people want most is not espadin. it's wild agave. >> but wild agave has its own problems. as production of mezcal has increased 700% from ten years ago, some species of agave are vanishing. so carreno germinates the seeds from 12 varieties in her nursery. >> how concerned are you about the future of the agave plant in oaxaca? >> translator: where do i start? on the one hand we have economic success because this spirit that came from ou