Native to North America and Asia, the crabapple tree is believed to be a remnant of the wild apple trees that once covered the planet. Today, there are hundreds of varieties available with most grown for their dazzling display of fragrant blooms. The blooms appear in spring, setting landscapes everywhere awash in shades of pink, red and white. Their beauty stretches across the seasons, however, with small fruit arriving once the blooms fade, turning to vibrant fall shades when autumn arrives and remaining for a stark contrast against winter’s backdrop.
Crabapples, if not of the disease resistant varieties, are susceptible to apple scab, a fungal disease that affects both leaves and the fruit of apples and ornamental crabapples. The fungus spends the winter in hibernation on fallen diseased leaves from the prior season. Once spring arrives, the fungal spores are released from the fallen leaves and carried via the wind to fresh foliage, flowers, fruit or new branches of nearby crabapple trees. Once on the tree, the fungal spores often travel through the tree canopy as the breeze blows and rain falls, spreading the disease to even more areas of the tree. Once infected, the tree’s leaves develop olive colored velvety spots, eventually turning to yellow, then brown as the disease progresses. As the leaves become more infected, they die and drop to the ground, leaving the tree barren long before winter.
For those wanting to protect their trees from becoming barren too early, it is important to treat your crabapples with the proper fungicide. Applied properly, the fungicide acts as a protectant against the infection. Trees should be sprayed twice in early spring for proper prevention (when leaves first appear) and then three to four weeks later when the flowers have fallen off. The disease cannot be stopped once symptoms are observed in mid-summer.
The treatment helps prevent spores from taking hold to the leaves. As the tree gets larger, it is impossible to spray every leaf on the tree, especially interior leaves, and some leaf drop in late summer is to be expected. Newer varieties of crabapples are mostly resistant to the disease, but we have found that the resistance lessens after a tree reaches 10 years of age. To keep your crabapple healthy for the 30-40 year lifespan of a typical crabapple tree, it is very important to spray yearly for prevention of the apple scab.
Do have a crabapple tree? Curious about the best way to maintain and care for it? Schedule a tree consultation with one of our ISA Certified Arborists today! Request a quote online now, or give us a call at 515.987.0800!