Hemp growers and entrepreneurs rejoiced a year ago when U.S. lawmakers reclassified the plant as a legal agricultural crop. Now, they worry their businesses could be crippled if federal policymakers move ahead with draft rules for growing the cannabis plant closely related to marijuana. The U.S. Department of Agriculture has extended the comment period on its proposal by a month after farmers, processors and officials in nearly every state raised concerns. Most of the anxiety involves how the government plans to test for THC, the high-inducing compound found in marijuana and hemp. The USDA says it will analyze information from this year’s growing season before releasing its final rules, which would take effect in 2021.