In the United States the biggest crop of commercially grown plums comes from hybrids of Asian stocks introduced by Luther Burbank in the 1870s. Burbank brought trees from Japan, planted them on his farm in Santa Rosa, California, and through crossbreeding produced many modern varieties still popular today. California produces about 90% of the commercial crop - more than two hundred varieties that ripen from early to late summer, with a few varieties ripening into the fall, according to studies by the Agricultural Issues Center at UC Davis.
In addition to California, plums are grown in New England and the Midwest, and indigenous varieties grow from the Mississippi River west to the Rocky Mountains and from Canada to the Gulf States.
Consumption of fresh plums in the United States has remained relatively constant since 1970, with annual fluctuations ranging from 1.9 pounds per capita in 1987 to 0.9 of a pound per capita in 1995. In 1970, per capita consumption of fresh and processed plums peaked at 5.4 pounds, with 72% of consumption consisting of processed (canned, frozen, juiced, or dried) plums.
The announcement that China will import California plums (April 2006) has put a new focus on plum imports and exports. Plum imports into the United States face two tariff seasons. From January 1 through May 31, shipments from countries with which the United States maintains normal trade relations do not face tariffs. Imports during the rest of the year are charged 0.5 of a cent per kilogram. Trading partners that have had the normal tariff status suspended by specific legislation face a tariff of 1.1 cents per kilogram any time of the year.
Before the Canadian-U.S. Free Trade Agreement, Canada imposed a tariff of 3.31 cents per kilogram on plum imports. Under the agreement, the tariff was reduced over 10 years until it reached zero in 1998. Mexico charged a tariff of 20% ad valorem on plums from the United States before NAFTA. That tariff was reduced over 5 years and fell to zero in 1998.
Before 1989, two U.S. tariff periods existed for plums. From January 1 through
May 31, no tariffs were applied. From June 1 through December 31, the United States charged 1.1 cents per kilogram. Under CUSTA, that tariff was gradually reduced and reached zero in 1998. Under NAFTA, the U.S. tariff for plum imports from Mexico was eliminated immediately.