Introduction to Plums

(Prunus species)

Plums are by far the most diverse of all the Prunus species and could be the most diverse of all deciduous fruit crop species. Native species of plums exist in nearly every temperate climate zone in the world where there is sufficient chilling to break dormancy. With diverse genetic material, plums are the ideal species to play a central role as a fresh fruit for local/regional marketing systems. Adapted cultivars can be found or bred for any temperate region of the country (and world).

Conversely, local/regional marketing and distribution systems with short supply chains are the ideal way to market this fruit. Most plum varieties are not suitable for large scale handling, shipping and distribution. The few that are do not represent the wide range of flavors and textures that this species has to offer. Fruit is often harvested before achieving full flavor and nutritional value in order to expedite handling. Plums harvested before full maturity can be mealy and bland because texture and flavor depends crucially on developing sugars in the final stage of ripening. Tree-ripened plums are not only delicious to eat fresh, they are also high in antioxidants, minerals, vitamins and other phytonutrients. (See USDA nutrient data, linked below.)

Plant breeders and researchers from around the country are recognizing the need to breed and select regionally adapted cultivars with high quality fruit, a task that is made easier by the genetic diversity available. In the 2006 publication New Alternative Fruit Crops for Western Washington, researchers from Washington State University identified plums as very promising (their highest category) and said, “…the economic and marketing aspects, however, now needs to focus primarily on high-end, quality dessert type fruit for the fresh market rather than drying or processing, with effort given to developing access to specialized consumer niche markets.” This statement holds true for today’s evolved consumer interest in fresh, healthful, unprocessed foods. The reference to niche marketing should be changed to local/regional marketing, an evolving concept with a much larger economic potential.

Every environmental region of the country needs its own breeding and cultivar selection program to optimize the potential of this diverse fruit. Cultivars selected for optimal adaptability and fruit quality in the Northwest will most likely not be suitable for the Midwest, for example. The Midwest has been fortunate to have had some good breeding programs in the past, a tradition that is being continued by Dr. Brian Smith, professor, plant breeder and Extension fruit specialist at the University of Wisconsin-River Falls.

Selections from Dr. Smith’s breeding program, along with other cold hardy cultivars suggested by him, are being observed in the Carandale test plot. Dr. Smith consulted on the design, layout and pollinizer matrix for this twice replicated cultivar trial. Additional cultivars have been added. Originally, all cultivars not sourced from Dr. Smith’s breeding program were purchased from a single provider of cold hardy nursery stock to eliminate possible differences due to nursery management practices. St. Lawrence Nurseries was chosen as the primary source for plum stock because of their northern location and reputation for supplying cold hardy, adapted cultivars. Planting stock was quite variable in size with some pruned back severely and some not. Despite this variability, everything survived transplanting and adapted well.

Selections being observed are grouped by species and/or cultivar types.

  • Non-native seedling (Prunus salicina)
  • Native seedling (Prunus americana)
  • Cherry-plum hybrids (Prunus besseyi x P. ssp.)
  • European plum (Prunus domestica)
  • Asian/American hybrids (Prunus spp.)

References

USDA Nutrient Data Laboratory: plums, wild plums

Washington State University information on plums

G.A. Moulton and J. King. 2006. New Alternative Fruit Crops for Western Washington. Washington State University.

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