Otto Luyken Suddenly Dying - Ask Extension
I've had these shrubs in front of our house for years. I noticed a few brown leaves so was going to cut them out. Instead I find one bush almost c...
Knowledgebase
Otto Luyken Suddenly Dying #596755
Asked September 14, 2019, 5:00 PM EDT
I've had these shrubs in front of our house for years. I noticed a few brown leaves so was going to cut them out. Instead I find one bush almost completely covered with a sticky white substance in the wood. All those branches are dead. It has spread to the plant next to it. This has all been very recent. What might it be and is it treatable?
Montgomery County Maryland
Expert Response
The shrub looks like a cherry laurel. The white coating on the branches is an infestation of white prunicola scale. They are insects that feed on the plant sap. This causes leaf yellowing, leaf drop, and branch dieback. This insect is difficult to control and we recommend removing the heavily infested shrubs.
If you want to try to manage it, you can brush off the scale with a soft brush. When the plant is dormant, (look at other deciduous plants and see when they drop their foliage) you can spray with a dormant horticultural oil. Follow all label directions. This may help to reduce the population, however, you will have to monitor the plants next spring. If you see crawlers (juvenile scale insects) in June, you can spray with a summer rate of horticultural oil. You may decide to remove the shrub and plant another type of plant if you cannot get control.
Take a look at our blog on cherry laurel and how to grow this plant in your landscape. https://marylandgrows.umd.edu/2019/01/07/qa-whats-wrong-with-my-cherry-laurel-shrubs/
Marian
If you want to try to manage it, you can brush off the scale with a soft brush. When the plant is dormant, (look at other deciduous plants and see when they drop their foliage) you can spray with a dormant horticultural oil. Follow all label directions. This may help to reduce the population, however, you will have to monitor the plants next spring. If you see crawlers (juvenile scale insects) in June, you can spray with a summer rate of horticultural oil. You may decide to remove the shrub and plant another type of plant if you cannot get control.
Take a look at our blog on cherry laurel and how to grow this plant in your landscape. https://marylandgrows.umd.edu/2019/01/07/qa-whats-wrong-with-my-cherry-laurel-shrubs/
Marian
