Ask A Master Gardener – Crab Apple Trees: Bust or Boon?

Crab apple trees (malus species) are closely related to apple trees, but with smaller, edible fruits.

Ornamental, or flowering crabapples are small to medium trees ideal for urban lots. Because of their smaller stature, they can grow under power lines or fit into a patio setting.  They can be used as specimen trees, background trees, grouped as a screen, or set up as a wildlife habitat.

There are more than 650 different cultivars of crab apple trees in a variety of sizes and forms, with different leaf, fruit, and blossom colors. When choosing one for the landscape, take care to evaluate disease resistance and fruit characteristics. There are many with smaller-sized fruits that persist (stay on the tree) during the winter, taking that “messiness” factor out of the equation.

In the spring, flowering crab apple trees live up to their name. They burst forth with single (5 petal), semi-double (6-10 petals), or double (10 or more petals) red, white, or pink blooms.  The buds are attractive before they bloom and may be a different color before they open.  For instance, the bud may be a red-purple while the bloom itself is white.

Once the blooms are done, the fruit develops. Fruit can be from ¼ to 2 inches in diameter and is yellow, orange, purple, pink, green, or brilliant red.  The fruit of many newer varieties will remain on the trees far into the winter.  It is edible and makes delicious jellies, cider, spiced apples, and sauce.  In addition, wildlife will be grateful for the fruit.  Birds, small mammals, deer and even insects will dine on the smorgasbord of blossoms and fruit.

But, the beauty does not end with the blossoms and fruit. Some of the trees have showy fall display ranging from yellow to red to orange to purple.  The branching of crab apple trees make interesting silhouettes for winter interest when leaves are absent.  Even the bark will develop an attractive mottling as the tree matures.

Beauty aside, crab apple trees do have some disease issues, including fire blight, apple scab, rust and powdery mildew. Therefore, cultivar selection is important.  The following link lists the top ornamental crab trees for Wisconsin: http://hort.uwex.edu/files/2014/11/Top-Ornamental-Crabapples-for-Wisconsin.pdf . These trees have proven to have the best disease resistance and will do well in the landscape.   In addition, cultural practices such as avoiding excessive shading, avoid excessive nitrogen, and allowing for adequate air circulation around trees will minimize these diseases.

Once established, crab apple trees are drought tolerant. They do prefer full sun, but can withstand light shade.  Excessive shade will result in increased disease and less than ideal fruiting and flowering.  While crab apples trees will tolerate a wide range of soils, well-drained soil is most important. Planting them in turf areas introduces them to more water and fertilizer than needed and again results in more disease.  A better choice is planting them in a mulched bed where their needs can be individually met.

As with any other apple tree, some pruning is recommended. Keep an open center of the tree for good air circulation and light penetration.  While crab apple tree wood is strong and does not suffer from significant winter/ice damage, proper pruning will keep the tree structure sound and minimize any branch damage.  Remove dead or broken branches, any that are crossing, as well as any growing straight up (water spouts).   Some varieties will grow suckers at the base and these should be removed regularly.  Planting the tree to deeply will contribute to suckering, so take care to properly plant initially.

While crab apple trees might not have come to mind at first, as the old saying goes, “Take a chance, Columbus did.”  The beauty, wildlife benefit, and edible fruit is worth any inconvenience.

Carol Shirk

Certified Master Gardener

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