Problems With Otto Luyken Laurel

by Melody Lee

The "Otto Luyken" laurel (Prunus laurocerasus “Otto Luyken”) is a small cultivar of the cherry or English laurel (Prunus laurocerasus), which is hardy in U.S. Department of Agriculture plant hardiness zones 6 through 8. It grows 3 to 4 feet high and 5 to 7 feet wide. It makes an attractive specimen plant with glossy green leaves and showy flowers. It can also be used in a hedge or a mixed border. The proper cultural care of “Otto Luyken” laurels will help prevent damage from diseases and pests.

1. Culture

“Otto Luyken” laurels need well-drained organic soil. Although they can live on a small amount of water, they grow better with a moderate amount of water. Do not water or fertilize excessively, as this can lead to problems with diseases. They grow in full sun to partial shade, and will even tolerate dense shade. “Otto Luyken” laurels grow in USDA zones 3 to 9.

2. Shot Hole

Shot holes begin as small purple or red spots on the leaves of “Otto Luyken” laurels. The centers of the spots turn brown and fall out, leaving small circular holes. They can be unattractive, but they do not affect the health of the plants. Shot holes are more common during mild wet summers. Remove and destroy infected leaves and avoid overhead watering to reduce the number of shot holes.

3. Root Rot

“Otto Luyken” laurels are susceptible to root rot caused by the Phytophthora fungus, especially in soggy soil. Diseased plants wilt, and the twigs and branches die back; a plant may even die. The leaves are discolored, stunted and fall off prematurely. Cankers, stains or streaks often develop on the trunks of diseased plants. Cinnamon brown or dark gray patches form under the bark and black or reddish-colored sap oozes from infected areas in the bark. Proper irrigation and good drainage will prevent root rot.

4. Scale Insects

Greedy and oleander armored scale insects are prone to attack “Otto Luyken” laurels, but the damage is usually minimal. Armored scale insects have soft bodies protected by a flattened plate-like cover. As the insects mature they secrete a substance to enlarge the cover, creating concentric rings. Only the crawlers and adult males move. Adult females stay in one spot their entire lives. As they feed, they lose their legs, molt and form their plate-like covers. To control a light infestation, remove and destroy infested plant material. To control a heavy infestation, spray the entire plant with horticultural oil. It is essential to completely cover all of the parts of the plant to control armored scale insects.