What’s Wrong with My Laurel?

Laurels are a popular landscape plant in our region, with good reason. They have thick, evergreen foliage that provides year round structure and privacy. They are one of the options that I mention in a previous blog post Fast Growing Plants for Privacy Hedges.

While Laurels can be very low maintenance, they do battle a few different pests that can be quite challenging to overcome once they take hold. Remember, the most effective plant health care plan is a preventative plant health care plan.

In plant health care, we often talk about a spiral of plant decline. The process whereby a plant or tree that is already battling poor predisposing factors (such as the wrong planting spot, poor soil, poor care at the nursery, etc.) that is then exposed to an inciting factor such as a period of drought, an unusually harsh winter, construction damage, etc. The inciting factor severely weakens the plant and sends the plant into a spiral of decline. At this point, the weak shrub or tree is a prime target for opportunistic pests that can easily prey on the plant until it’s death.

With Skip Laurels in our region, I tend to notice that the presence of a single one of the pests listed below is often not enough to kill the plant. However, if the single pest problem is not addressed, the plant is weakened, allowing a second or third problem to occur. These problems combined then become too much for the laurel to defend itself against, resulting in the death of the plant.

If you observe any of the pests below, or if your Laurels are looking otherwise unhealthy, please reach out. We can treat for all of the pests below preventatively. We can also fertilize annually or bi-annually to replace the nutrients in your soil. This ensures that your shrubs are the healthiest they can possibly be - making them ready to fight off any pesky bug or disease!

Insects:

• White Prunicola Scale - Pictured below on the left (click image to enlarge) is a severe White Prunicola Scale infestation. The bark of this Skip Laurel shrub is covered with small white scale insects, which attach themselves to the wood of the plant and suck out it’s nutrients. This scale is difficult to control because it has a hard shell exterior, making it immune to spray control. Soil-injected insecticide must be used so that the product is taken up throughout the plant. When the scale sucks on the wood, it ingests the insecticide and dies.

• Black Vine Weevils - Pictured below on the right is foliar damage done by vine weevils. Vine weevils are an insect that lives in the soil at the base of the plant. At night, the adult weevils emerge to feast on this Skip Laurel’s leaves, creating a distinct notched appearance along the leaf margin. Soil-injected insecticide must also be used to control this insect.

Disease:

• Cherry Shot Hole Fungus - Both images below show the disease progression of a fungus called Cherry Shot Hole. (Cherry refers to the Prunus genus, which this fungus favors). Early on in the disease cycle, this fungus creates yellow spots on the foliage of the Laurel. As the disease progresses, a dark brown or black inner circle develops, which eventually kills the center of the splotch. The brown spot falls through the center of the splotch, resulting in the holes shown in image on the righthand side. Cherry Shot Hole fungus can be controlled by spraying a mixture of appropriate fungicides on the leaves 3x throughout the wet spring and early summer period.

• Phytophthora Root Rot - This root rot disease is caused by a soil-borne fungus that develops in particularly wet, poorly drained soils. It attacks the roots of the Laurel shrub, inhibiting its ability to transport water and nutrients. This results in leaves that turn light green or yellow and eventually fall off the plant. Root rot typically causes a slow decline of the shrub and can easily be overlooked. We recommend treatment with a soil drench of fungicide. If possible, it is also beneficial to amend the soil with sand to help with drainage.