| Abstract/Contents: | "crab apple (krab 'ap l) n. 1. any of several species of terrible little trees well known for their propensity to litter the ground with rotting fruit and defoliate in July. 2. so-called ornamental trees sold by dishonest nurseries and garden centers. 3. a homeowner's worst nightmare. Unfortunately, many homeowners might not see the humor in this tongue-in-cheek definition of crabapples. Thanks to cultivars such as 'Dolgo', 'Hopa', 'Radiant', and 'Royalty', which were planted heavily over the last 20 to 30 years, the public has had ample opportunity to see trees without leaves in August and experience messy fruit drop. It's a wonder that nurseries are able to sell crabapples at all with cultivars such as 'Radiant' serving as goodwill ambassadors. Today, most nursery operators are aware that superior cultivars of the genus Malus exist. These trees produce small, persistent fruit and show excellent disease resistance. Nurseries and garden centers are obliged to sell these preferred cultivars and varieties and phase out more troublesome species. Only when this is done will the general public begin to regain faith in a truly remarkable group of small ornamental trees. Iowa State University is one of 23 cooperators taking part in the National Crabapple Evaluation Program (NCEP). Each trial site is currently evaluating over 50 crabapple varieties and cultivars for disease resistance and outstanding ornamental features. ISU is also participating in the National Crabapple Introduction Program (NCIP), established to evaluate new taxa. Cultivars and varieties demonstrating superior quality at the Ames, Iowa, trial site are described below. 'Adams'- Originated in the late 1940s at the West Springfield residence of the late Walter Adams, former president of Adams Nursery, Westfield, Massachusetts. Trees are rounded and dense, growing about 20 ft tall with an equal spread. In spring, deep carmine buds open to single reddish-pink flowers. The light-green foliage exhibits a reddish tinge on new growth and is only slightly susceptible to powdery mildew. The 5/8 in fruit of 'Adams' colors a dark red by the middle of July, but will persist until the following spring. Use the tree in mass plantings or as a single specimen. 'Candied Apple'- A popular weeping form growing 10 to 15 ft tall developed at Lake County Nursery Exchange, Perry, Ohio. Dark red buds open to single, pink flowers in spring and leaves are dark green with just a hint of brownish-red. The bright cherry red fruit are 5/8 in in diameter and may persist until late winter. 'Candied Apple' reportedly has slight to moderate scab susceptibility; however, this disease has not affected trees in Ames. Use it in place of the disease-prone weeper 'Red Jade'. 'David'- Named in 1957 by Arie F. denBoer after a grandson, this round and compact tree will grow to a height of approximately 20 ft. Flowers are light pink in bud, opening to moderately fragrant single white blooms. Fruit are 1/2 in in diameter, scarlet red, and very persistent. Unfortunately, the dense dark green foliage of 'David' tends to conceal the attractive flowers and fruit. This cultivar is only slightly susceptible to scab and fireblight. 'Donald Wyman'- Given the name of the famous horticulturist in the late 1940s, this cultivar remains a standout among the hundreds of available crabapples. Dark-green foliage is dense on this tree's rounded, 15 to 20 ft tall frame. Pink buds open to mildly fragrant single white flowers and an abundant crop of bright red 3/8 in fruit is produced annually. The persistent fruit are a welcome addition to bleak winter landscapes. 'Donald Wyman' is only slightly susceptible to powdery mildew. 'Harvest Gold'- This vigorous cultivar grows 15 to 20 ft tall and maintains a neat, upright habit, perfect for narrow boulevards or other sites where space is limited. Single white flowers are followed by 3/5 in golden-yellow fruit that remain effective well into December. 'Harvest Gold' is highly resistant to all major crabapple diseases. 'Professor Sprenger'- This wonderful cultivar, introduced in 1950 by Mr. S. G. A. Doorenbos of the Hague, Netherlands, is still struggling for acceptance in this country. The tree grows to the heights of 20 to 25 ft and develops a spreading, global shape with maturity. Abundant snowy white flowers are produce in spring followed by eye-catching 1/2 to 5/8 in orange-red fruit in late summer. Because birds shun the fruit, these colorful ornaments are allowed to remain on trees until midwinter. Some have found the dried fruit makes interesting additions to floral displays. 'Professor Sprenger' is highly disease resistant. There is no shortage of desirable crabapples for midwestern landscapes. Some like 'Bob White', 'Indian Magic', 'Profusion', 'Sentinel', and 'Snowdrift' have been around for years, while newcomers 'Adirondack', 'Doubloons', and 'Louisa' show promise for the future. It is time for responsible growers and retailers to introduce superior cultivars and varieties to homeowners, landscape architects and designers, and other grounds maintenance personnel throughout our region. The International Ornamental Crabapple Study had been formed to bring together breeders, wholesalers, retailers, horticulturalists, scientists, and hobbyists who are interested in crabapples with the intent to educate the public and eliminate substandard plant material from the market place. Persons wishing to join IOCS may contact Dr. Thomas Green, Research Plant Pathologist, The Morton Arboretum, Lisle, Illinois 60532." |
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