WASHINGTON — Secretary of Agriculture Sonny Perdue on Dec. 20 announced the National Bioengineered Food Disclosure Standard, which requires food manufacturers, importers and certain retailers to label foods containing genetically modified or bioengineered ingredients.

“The National Bioengineered Food Disclosure Standard increases the transparency of our nation’s food system, establishing guidelines for regulated entities on when and how to disclose bioengineered ingredients,” Mr. Perdue said. “This ensures clear information and labeling consistency for consumers about the ingredients in their food. The standard also avoids a patchwork state-by-state system that could be confusing to consumers.”

The standard defines bioengineered foods as those containing detectable genetic material that has been modified through lab techniques and may not be created through conventional breeding or found in nature. Implementation of the standard begins Jan. 1, 2020, or Jan. 1, 2021, for small food manufacturers. The mandatory compliance date is Jan. 1, 2022. Regulated entities may voluntarily comply with the standard until Dec. 31, 2021.

The Agricultural Marketing Service of the U.S. Department of Agriculture developed a list of bioengineered foods to identify crops or foods that are available in a bioengineered form and for which regulated entities must maintain records to inform whether a food product must include labeling of bioengineered ingredients.

Regulated entities may use text, a symbol, an electronic or digital link or a text message to disclose bioengineering. Additionally, a phone number and web address are available for small food manufacturers or for small packages.

Certain products made from the 13 bioengineered crops and foods on the U.S.D.A.’s list do not require labeling. The list of bioengineered foods are alfalfa, canola, corn, cotton, potato, salmon (AquAdvantage), soybean, squash, sugarbeet and certain varieties of apple, eggplant, papaya and pineapple.

“For refined foods that are derived from bioengineered crops, no disclosure is required if the food does not contain detectable modified genetic material,” according to the advance Federal Register notice. As such, refined beet sugar, soybean oil and corn sweeteners, all mostly from bioengineered seed, would not need to be labeled as a bioengineered ingredient under the new rule. Adequate testing must have been performed to prove that there was no detectable material, though.

Robb MacKie, president and chief executive officer of the American Bakers Association, said the requirements will provide “clear and concise messaging that consumers seek and will streamline changes efficiently with cost savings for our industry.”

“The baking industry has supported a federal standard for bioengineered food disclosure, which is necessary for interstate commerce,” Mr. MacKie said.

Lynn Chrisp, president of the National Corn Growers Association and a farmer from Nebraska, said the association is pleased with the issuance of the rules, noting that farmers need a “consistent, transparent system to provide consumers with information without stigmatizing important, safe technology.”

“N.C.G.A. came together with stakeholders from across the value chain to support enactment of the Bioengineered Food Disclosure Act because it prevented a state-by-state patchwork of labeling laws that would have cost U.S. consumers, farmers and manufacturers billions of dollars,” Mr. Chrisp said. “We are hopeful that this rule will be a major step in achieving our important, shared goals.”

Davie Stephens, president of the American Soybean Association and a soy grower from Kentucky, also noted his group’s support for the rule.

“Soybean farmers are pleased that U.S.D.A. took the time to do this rule the right way,” he said. “We believe that it allows transparency for consumers while following the intent of Congress that only food that contains modified genetic material be required to be labeled bioengineered under the law, with food companies having the option of providing additional information if they choose.”

The National Grain and Feed Association said it was pleased the U.S.D.A. adopted many of its recommendations. The N.G.F.A. said it was especially pleased with the final rule’s 5% disclosure threshold, which it said appropriately balances disclosure, market dynamics and international trade.

“The bioengineered food labeling standard is about providing more access to information to consumers; it most emphatically is not a food safety standard,” the N.G.F.A. noted.

Not all groups were pleased with the new rule, though. Both the Environmental Working Group and the Institute for Agriculture and Trade Policy took shots at the legislation.

“It is obvious that this rule is intended to hide, not disclose, information about genetically modified foods,” said Sharon Treat, senior attorney for the I.A.T.P. “Many manufacturers will be able to evade even the minimal requirements of the rule, and it will sow confusion and burden consumers with the responsibility of researching food ingredients themselves. Instead of clear on-package labeling, consumers will have to call or text manufacturers to find out what’s in their food — something they can do already. The rule adds nothing good to existing voluntary certification programs and continues to preempt effective G.M.O. labeling programs adopted by states, including Vermont.”

Scott Faber, senior vice-president of government affairs with the E.W.G., accused the Trump administration of putting the interests of pesticide and biotechnology companies ahead of the interests of ordinary Americans.

“The final G.M.O. disclosure rule fails to meet the clear intent of Congress to create a mandatory disclosure standard that includes all genetically engineered foods and uses terms that consumers understand,” Mr. Faber said. “A fair standard should address the needs of consumers who don’t have expensive phones or who live in rural places with poor cell service but the rule put forward today simply fails to do that.

“At a time when consumers are asking more and more questions about the use of genetic engineering, today’s rule will further undermine the technology by sowing greater confusion among Americans who simply want the right to know if their food is genetically modified — the same right held by consumers in 64 other countries.

“Despite today’s disappointing, and likely unlawful, decision, we are pleased that companies that trust consumers — including Campbell’s, Mars, Danone, Kellogg’s, Coca-Cola and Unilever — will voluntarily disclose all G.M.O.s in all their foods, not just in those required by the final rule.”

The implementation of the standard follows a rulemaking process that began in July 2016. More than 14,000 comments were received and considered during the rulemaking process. Previously, more than 112,000 comments were received in response to 30 questions regarding the establishment of the standard.

The final rule was published in the Federal Register on Dec. 21.