- A member of the rose family, crabapple trees blossom in a range of colors from white to red, and the blossoms range from five petals to ten, all of which depends on the variety of the crabapple tree. Most species of crabapples bear fruit in summer or fall, and these round fruits are typically 2 inches in diameter or less.
- Fire blight is a destructive disease, attacking different areas on the crabapple tree. This disease is a bacterium that survives through the winter, living in the bark of the tree. Early signs of an infected tree show blossoms that are a gray-green color then turn black. As well, new shoots on the stem will turn black and bend into a hook-shape, referred to as shoot blight. Fire blight infects the older wood of the tree, sometimes killing entire branches or the tree itself.
Crabapple Tolerance to Fire Blight
- There are numerous species of crabapples, and while some are somewhat tolerant of fire blight, some varieties are highly susceptible to the disease. Some varieties of crabapple trees that are slightly resistant are Centurion, Coralburst, David, Evereste, Indian Summer, Profusion, Radiant, Red Vein Russian, Thundercloud, Vanguard and White Cascade. It's important to remember that even though these varieties are resistant, this does not mean they are immune to fire blight.
Maintenance & Prevention
- Colorado State University's Extension program says that there isn't a true cure for fire blight, so preventing the disease is the best option. Preventing fire blight starts with planting crabapple tree varieties that have some resistance to the disease. Slow rapid new growth of the crabapple tree since fire blight easily attacks these new shoots. Minimize the nitrogen fertilizer used since this helps slow new shoot growth.
- When a crabapple tree is infected with fire blight, prune out any shoots that are showing signs of blight (curling, blackening). For best results, prune 8 to 12 inches back from the blight, and sterilize the shears after each cut to avoid further contamination. According to Cornell University's Integrated Pest Management Program, you may also want to apply an antibiotic spray during the blooming season of your crabapple tree since fire blight can turn into a serious epidemic during the tree's bloom period.