Flowering crabapples are more than ever a popular and attractive choice for ornamental landscapes. They put on a spectacular display of blossoms in spring and a fruiting extravaganza in fall that are unrivaled by any other shrubs or trees. Their rich green or reddish summer foliage and picturesque tree forms add to their long season of interest.
In recent years, the number of splendid crabapple cultivars has increased dramatically, counting over 1,000 cultivars and hybrids, creating a profusion of varieties from which the gardener may select the perfect combination of size, form, color, fragrance, fruit, hardiness and resistance to pests and diseases.
Crabapples are susceptible to four major diseases which can cause early defoliation, disfigurement and weakening of trees.
- Apple scab is the most common and most serious of the diseases, especially in areas which receive plenty of springtime moisture. It disfigures the fruit and defoliates the trees. It shows up on leaves as olive green spots with a velvety, grayish surface. In midsummer leaves often turn brown and drop from the tree.
- Fireblight occurs less frequently but is more serious because it kills bark and can spread to the main trunk and kill the tree. Affected blossoms, shoots and branches turn brown and have a scorched appearance, hence the name fireblight.
- Cedar-apple rust is common where red cedar and crabapple are planted near each other. Orange spots or swellings appear on crabapple leaves, fruits and twigs.
- Powdery mildew appears in midsummer as patches of grayish white powder on leaves and fruit.
The Pacific Northwest may not be the best place to enjoy the long-lasting beauty of flowering crabapples. Many older crabapple varieties grown in the past adapted poorly to the cool, constant humidity of the region. Diseases such as apple scab and powdery mildew took their toll.
Breeders have been busy improving the disease-resistance of flowering crabapples. Here is a list of varieties and cultivars that consistently perform well in the Pacific Northwest Region.