Disease Resistant Ornamental Tree Fruit: Malus, Prunus & Pyrus
New varieties of ornamental fruit trees with improved disease resistance offer a wide range of bloom times, flower type and color, variable tree habits, and general characteristics suited to many diverse landscape uses, from urban patios and backyards to large park and wayside trees. Good disease resistance is especially important in maritime climate areas like ours where bacterial and fungus infections are common. Susceptible trees can easily become a landscape eyesore rather than an asset, and spread infection to healthy trees as well.
WSU Ornamental Tree Fruit Arboretum
A joint effort of WSU Mount Vernon NWREC and state, local, and national nursery and landscape organizations, the arboretum presents top rated selections of ornamental flowering fruit trees that are well suited to growing conditions in the cool maritime climate of the Puget Sound region, with good disease resistance, easy maintenance, and year-round attractiveness in home landscapes, parks, and urban plantings. Visit the Arboretum to see and appreciate the wide selection of different ornamental fruit trees that are available to enhance home and public garden areas with their diverse forms, sizes, and colors. The arboretum is located on the grounds of the WSU NWREC west of the Demonstration Fruit Garden (Driving directions).
The test planting of ornamental fruit trees at WSU Mount Vernon NWREC was begun in 1984 in cooperation with the International Ornamental Crabapple Society, as part of the National Crabapple Evaluation Project. Crabapples are defined as those taxa (varieties and species) in the genus Malus bearing fruits 2 inches in diameter or smaller.The project included replicated plantings of 3 trees per variety established at 24 different sites across the U.S. The purpose was to test new crabapple introductions for year-round ornamental quality and disease resistance under widely differing climate conditions. From1984 to 2009 we tested some 60 varieties (taxa); some were eliminated for poor performance and new introductions added. Several new crabapple varieties from the NCEP were planted in 2000 and in 2004 the trial was expanded with the addition of ornamental cherry, plum, apricot and pear cultivars. Yearly evaluations in spring and fall included bloom date, bloom density and type, fruit color, size and persistence, disease susceptibility, and overall esthetic quality. Research in the ornamental orchard was ended in 2009 when the Tree Fruit Horticulture program at WSU Mount Vernon was terminated; in 2013 the orchard was opened to the public as an Arboretum.
A crabapple rootstock trial was conducted from 1997–2001 to document the size-controlling effects of known dwarfing rootstocks on certain ornamental crabapple varieties with good disease resistance and differing growth characteristics.
Crabapple Rootstock Trial Report (2002, revised 2014)
Ornamental Fruit Trees for Puget Sound Landscapes (2013). Presentation on flowering fruit trees and their landscape uses in northwest Washington.
Ornamental Fruit Trees for the Puget Sound Region (2013). Characteristics for choosing flowering fruit trees and list of varieties that have performed well in northwest Washington.
Ornamental tree fruit – 2009 List of ornamental tree fruit varieties in 2009 (last year of the trial).
Crabapples…with no apologies. 2009. Jeff Iles, Iowa State University, Ames, IA
A 33-year evaluation of resistance and pathogenicity in the apple scab – crabapples pathosystem. 2009. Janna Beckerman, James Chatfield, and Erik Draper. HortScience 44(3):599-60.
Selection Preferences for Crabapple Cultivars and Species. 2003. James P. Romer, Jeffery K. Iles, and Cynthia L. Haynes. HortTechnology 13(3):522-526.
Crabapple Information Chart 2014. J. Frank Schmidt & Son Co., Boring, OR.
Small Trees for the Home Landscape, EB2036/EB2036E, 2008. Charles Brun, Washington State University, 44 pp.
Flowering Crabapples: The Genus Malus. 1994. Fr. John L. Fiala, Timber Press, Inc., Portland, OR, 273 pp. including prints and color plates.
An outstanding reference book on ornamental crabapples, perhaps the most extensive now available. Contains information derived from Fr. Fiala’s lifetime experience as a breeder, and a comprehensive index of ornamental crabapple cultivars and species with descriptions and illustrations, disease resistance ratings and climate adaptability.
Flowering Crabapples. 1959. Arie F. DenBooer, American Association of Nurserymen., 226 pp.