Few landscapes plants can provide such varying choices in color, fruit and shape as the many cultivars of crabapples. The gorgeous flowers can vary from white to bright pink. The flowers put on a show in early spring and are followed by fruit that often lasts into winter with colors of yellows, pinks, and many shades of reds. There are literally hundreds of varieties of crabapples with many having been selected for flower and fruit color. The most common problem among many crabapple varieties is a fungus disease that attacks leaves and fruit called “Apple Scab”, Venturia inaequalis. When selecting a crabapple for your landscape, take some time to review lists of varieties not only for their color, but also for resistance to apple scab.

Apple scab on crabapples can leave plants looking fairly bare as the leaf spot disease causes leaves to drop from the tree throughout the summer. Some very susceptible varieties often will have only leaves at the tips of branches by early August. Cultivars selected as landscape specimens and planted to be a focal point of the site can end up being a huge eyesore. This disease is treatable with fungicides, but often requires repeated applications from budbreak through petal fall to prevent leaf drop. An Extension publication from Purdue University, Apple Scab of Flowering Crabapples, provides an in-depth review of apple scab and cultivar resistance.

As you investigate varieties that are less prone to apple scab, understand that “resistant” does not mean that the tree is immune to the disease. Under situations where a tree is planted too close to other trees, reducing air circulation, or where leaves are frequently wetted by a sprinkler, even some resistant varieties may be attacked by the disease. A little bit of research prior to plant selection could greatly reduce fungicide use in the future and the cost to maintain the landscape in a healthy state.

If you currently struggle with a crabapple that drops leaves each year due to apple scab, you have the choice to protect the plant yearly with multiple fungicide applications, do nothing and live with the unsightly leaf drop, or to remove the plant and replace it with a resistant variety. Sanitation can help reduce the presence of the disease from year to year by picking up and removing fallen crabapple leaves from the site. Visit MSU’s Integrated Pest Management (IPM) web site for more information on apple scab.