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Often, the crab's showy bloom is followed by scab or mildew infections that turn the trees into nearly leafless eyesores for the rest of the year, and damage their long-term survival. Many varieties commonly sold and planted such as Hopa, Liset, and Eleyi, have disease problems in the cool, moist climate areas of the Pacific Northwest. Healthy and attractive trees need an aggressive spray program for disease control; intensive spraying is becoming less acceptable on ecological grounds, not to mention the additional time and expense. The better answer is to select varieties with proven disease resistant qualities.
A test plot of 43 new, improved crabapple varieties was established at the Washington State University Mt. Vernon Research and Extension Unit in 1984-85. This planting is part of the National Crabapple Evaluation Program, organized by Dr. Tom Green of the Morton Arboretum in Lisle, IL, The program continues to evaluate recent introductions; in 1990-91, receiving nine new varieties, with seven more added in 1993.
Two ratings of all varieties are taken annually. The spring evaluation emphasizes bloom time and general appearance. Most crabapples are attractive at bloom time so although the amount and quality of bloom are considered in the rating, the most important evaluation is how a variety looks in the fall. The fall evaluation is taken in mid to late October, covering overall appearance and disease symptoms. The evaluation does not depend strictly on ratings of disease resistance, though disease immunity is preferable to tolerance.
To rate high in fall evaluations, a variety must have abundant, vivid colored fruit that does not drop and make a mess, and it should retain most or all of its leaves in a healthy condition. Certain crabapples, although moderately susceptible to scab and other diseases, may still keep their leaves and continue to look attractive in late summer and fall.
Based on evaluation, listed below are 17 varieties, some new and some already well known, which rated best at the test site. Most are suited to planting in cool maritime areas of the Pacific Northwest. The list is based on tree shape and bloom color. Upright trees are tall and narrow, upright spreading are tall with branches that open as the tree matures. Rounded trees have a dense, compact form, and low spreading trees, have a broad, horizontal structure, whether large or small. Color of fall fruit is noted in parentheses.
White flowers, Upright
White Flowers, Upright Spreading
White Flowers, Rounded
White Flowers, Low Spreading
Pink Flowers, Upright Spreading Bronze Red Foliage
Pink Flowers, Broad Spreading
In the listed selections there is not a top rated variety with a weeping habit, broad horizontal growth with trailing limbs. In preliminary evaluation of the young trees received in 1990, there were two promising weepers:
Several other varieties show both good ornamental quality and disease resistance, and may be future additions to the overall "best" list:
Varieties to Avoid:
Although many of these disease susceptible varieties are sold in local nurseries on the basis of their performance in other parts of the country, they simply are not suited to the maritime climate of the Pacific Northwest.
Almata Profusion Almey Purple Wave Bechtel Radiant Beverly Red Barron Candied Apple, Red Silver Weeping Centurion Red Jade Dorothea Robinson Eleyi Robusta Echtermeyer Royal Ruby Harvest Gold Royalty Hopa Ruby Luster Jay Darling Scheidecker Liset Van Eseltine M. micromalus Velvet Pillar Pink Perfection Winter Gold
Better crabapple varieties are now available that will look good in the landscape all year round. This promotes easier landscape maintenance and contributes to customer satisfaction. Nursery and landscape professionals are encouraged to gear their production toward increased use of the high rated varieties.
With the continued support of the Washington State Nursery and Landscape Association grant, our testing program is expected to continue for another few years as the newest varieties mature and evaluations are completed. We will be looking for high quality crabapples to fill the needs of landscapers and gardeners, and hope that at the conclusion of our project we will have a full range of crabapple choices, well adapted to our maritime climate conditions of the Pacific Northwest. The versatile crabapple will then merit a prominent place in the ornamental landscape inventory.
For further information, contact your local WSU
Extension Office or purchase EB 1809,
Crabapples for Western Washington
Landscapes ($6) at your local WSU Extension Office.
