Among the most prized of ornamental trees, flowering crabapples have long been a staple of landscape gardening. They are best known for their spectacular display of magnificent blooms in spring and colorful fall fruit. Their summer foliage, small stature and various tree shapes add to their charm and give them year-round 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.
Breeders have been busy improving the disease-resistance of flowering crabapples. Here is a list of varieties and cultivars that consistently perform well in Midwestern gardens.