As marijuana legalization in states like Colorado and Washington continues, marijuana farmers in Mexico are starting to see a steep decline in the profits their crops once fetched. Some growers report they’re seeing a decline in income as high as 70 percent, and they blame the popularity of higher quality legal marijuana in the U.S.

According to Fox News Latino, in the Mexican state of Sinaloa, one of the country’s biggest marijuana production areas, growers have reported that they have seen the price of their product drop from $100 per kilogram to $30 in the last four years. Juan Guerra, Sinaloa’s agriculture secretary, told the Los Angeles Times, “People don’t want to abandon their illicit crops, but more and more they are realizing that it is no longer good business.”

Mexican drug cartels rely heavily on growers of both marijuana plants and opium poppies to supply them with the materials necessary to their drug trade. Opium growers—known as gomeros for the gummy-like substance they extract from the opium pods—generally make good money compared to their peers growing traditional crops, especially since the U.S. demand for heroin has skyrocketed.

Marijuana has historically accounted for the largest volume of drugs being smuggled north, but pound for pound it is not the most profitable. Cartels still make billions of dollars in the marijuana trade because they can sell it in bulk and the demand is consistently high. However, American tastes are changing as more people are exposed to domestically grown seedless strains of the plant—generally considered to be of much higher quality than bulk marijuana grown outdoors in large Mexican plantations.

Per Fox News Latino, Mexico has been supplying as much as two-thirds of pot consumed in the U.S. However, in the last seven years, Mexican suppliers have lost roughly one-third of their market share. Both growers and dealers are adapting to the changes. Cartels are focusing on more profitable drugs like methamphetamine and black tar heroin, while some farmers have taken work as day laborers or in greenhouses growing tomatoes as part of a government plan to give farmers a chance at leaving the drug business. The income is nowhere near as generous.

Some Mexican legislators have considered enacting policies similar to those in Colorado and Washington, but the drug war violence dissuades many from actions that could be perceived as capitulating to the cartels.

Sylvia Longmire is border security expert and Contributing Editor for Breitbart Texas. You can read more about cross-border issues in her latest book, Border Insecurity: Why Big Money, Fences, and Drones Aren’t Making Us Safer.