The cherry laurel tree (Prunus caroliniana) is a member of the Rosaceae family and thrives in USDA hardiness zones 8 through 10A. It is a native North American tree that is often used as a hedge or lawn tree. If left unpruned, it can grow up to 40 feet in height with a spread of up to 25 feet. It has a medium growth rate, and grows a dense crown, which makes the cherry laurel tree popular in southern landscaping.
The bacterium Erwinia amylovora causes fire blight in cherry laurel trees. The disease destroys limbs, at a minimum, and if not caught, destroys the entire tree. One of the first symptoms of fire blight is a watery, light tan ooze that appears on the branches and twigs, and trunk cankers. Once the ooze hits air, it turns dark, leaving dark streaks on the branches and trunk. Fire blight overwinters in cankers, so must be treated as soon as you notice it. Avoid excess fertilization and heavy pruning to help combat fire blight. Do not irrigate the tree while it is blooming. Remove any branches or twigs affected with fire blight. If you had problems in the past with fire blight, apply apple blossom sprays in the spring. The sprays stop new infections, but do not kill current infections. Current infections should be pruned from the tree.
Stem canker starts as small, reddish lesions on the lower leaf nodes. As the disease progresses, the small lesions grow lengthwise, forming long cankers. There are two types of stem canker: northern and southern. The northern canker turns dark brown as it ages, and range from about 3/4 inches to 4 inches in length. The southern canker is long, seldom girdle the stem. In both cases, the tree eventually dies from the disease, if the disease is not managed. Northern canker is caused by Diaporthe phaseolorum var. caulivora, while Diaporthe phaseolorum var. meridionalis causes southern stem canker. According to the University of Illinois, the only defense against stem canker is to plant resistant cultivars.
Shade Tree Borers
There are several varieties of shade tree borers, including certain beetles and moths. The borers usually bother trees that are unhealthy. An unhealthy tree might be infected with a disease, or may not be fed or watered properly. According to Colorado State University, depending on the type of borer, its development takes one to three years to complete. If you notice borers in your cherry laurel tree, correct the problem: drought, injury, or disease. Visit your nursery to get the appropriate insecticide for the type of borer in the tree. Trunk sprays kill the adult borers during their egg-laying stage. Canopy sprays help control beetles and metallic wood borers.