The Santa Rosa plum was the most widely grown plum in California until the mid-1970s.

The Santa Rosa plum was the most widely grown plum in California until the mid-1970s.

The Santa Rosa plum, one of the most popular and widely known plum varieties in America, was named after the northern California city of Santa Rosa where Luther Burbank, the plum’s breeder, settled in 1875 after moving west from Massachusetts.

Burbank, who grew up on a farm, began his long plant-­breeding career at the age of 22. He was 26 years old when he sold the rights of his Burbank potato variety for $150 and used the money to move to California, establishing a nursery, greenhouse, and experimental farm in Santa Rosa. He is said to have proclaimed Santa Rosa as a “chosen spot of all this earth as far as Nature is concerned.” Tours are still given of his home and gardens, which are listed as a National Historic Landmark.

One of America’s greatest horticulturists and botanists, he developed more than 800 strains and varieties of plants, including more than 110 varieties of plums and prunes. Among the better-known plants he bred are the Shasta daisy, July Elberta peach, Wickson plum, Flaming Gold nectarine, and the Burbank potato. Russet Burbank, a genetic variant of Burbank with russeted skin, became the most widely cultivated potato in the world.

Burbank used hybridization in his breeding work, crossing foreign and native plant material. In his work on plums, he tested about 30,000 new plum varieties, according to the National Inventors Hall of Fame profile on Burbank. He was inducted into the Inventors Hall of Fame in 1986. Burbank died before U.S. patent laws were changed in 1930 to include asexually reproduced plants (tuber-propagated ones were already covered). However, more than 15 plant patents were issued to him posthumously.

Burbank’s plum breeding lives on in the research orchards at the U.S. Department of Agriculture’s Appalachian Fruit Research Station at Kearneysville, West Virginia, where some of his plum trees are being used in a molecular breeding project to develop pitless plums. One of Burbank’s great achievements, though never commercially successful, was the development of a pitless plum that resulted from crossing a naturally occurring wild plum variety that was partially stoneless.

Plum development

Early plums grown in America were European species (Prunus domestica). Spanish missionaries brought European plums to California, while English colonists brought them to the East Coast. ­California’s dried plum industry was built on European plum varieties.

But the Santa Rosa plum belongs to the Japanese plum group, Prunus salicina. Burbank didn’t introduce Japanese plums to the United States (John Kelsey, a nurseryman from Berkeley, introduced the species in 1870), but he imported 12 seeds from Japan in 1885 and crossed them with other plums, playing an important role in the development of plum varieties. In the book Peaches, Plums, and Nectarines: Growing and Handling for Fresh Market, authored by James LaRue and R. Scott Johnson, LaRue writes that “Nearly all current cultivated plum varieties were derived from those developed by Burbank.”

A winner

Burbank’s Santa Rosa plum was introduced commercially in 1907 by Fancher Creek Nursery in Fresno, California. The heart-shaped fruit, with red skin and red tinged-amber flesh, ripens in early June in California’s San Joaquin Valley.

Upon his death in 1926, Burbank willed more than 750 varieties to James H. Stark, founder of Stark Bros. Nurseries in Louisiana, Missouri. Stark and Burbank had become plant breeding associates, and Burbank selected Stark to carry on his work.

From 1945 to the mid-1970s, Santa Rosa was California’s number-one plum variety and represented more than a third of the plums grown in the state. But by the late 1980s, the dark-colored Friar plum overtook Santa Rosa in ­popularity, and Burbank’s offspring had slipped to number three, representing only 10 percent of production.

Sources for this article include: Peaches, Plums and Nectarines: Growing and Handling for Fresh Market, edited by James LaRue and R. Scott Johnson; California Tree Fruit Agreement annual reports; and the National

Inventors Hall of Fame and Museum, Alexandria, Virginia.