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Why are the leaves turning black on my shrubs?

Green leaves with white scales

Black shrub growing on plant leafOne question that we are often posed with is, “why are the leaves turning black on my shrubs??” It’s a common question because it is a pervasive issue for indigenous plants; however with systematic treatment, the problem is an easily preventable one. The correct answer is that you have scale, and the black on the leaves is the honeydew that is left behind as scale insects move throughout the plant.



What is scale?

Let’s take a closer look.

insects creating black shrubs on plantsScale is the result of scale insects sucking sap from your plants. What’s more, as scale insects make their way through a plant they rob them of essential nutrients. There are three types of scale: armored scale, soft scale, and mealybug. Armored scale and soft scale bugs are the most destructive, as mealybugs are easier to control with the implementation of the proper program. Armored scales are more difficult to control once they are matured, which is precisely why we offer a spring preventative at Sussex Tree. Soft scale bugs are difficult to control as well because they excrete the largest amounts of honeydew, which enables the growth of sooty mold – a black-colored fungus that can stunt plant growth by blocking the process of photosynthesis. Scales cannot fly, so all dispersal takes place through the movement of crawlers.

As we move into spring, it is important to take a proactive approach to scale prevention on your plants. With the warmer and drier weather we experienced this fall and early winter, there has been a noticeable abundance of all types of scale. At Sussex Tree, we suggest a systemic treatment during the spring (particularly during the end of March and beginning of April) to work as a preventative before the warm weather lures the scale insects out of hibernation. Contact us today to plan for your systematic scale treatment.

Having other issues with your plants? Check out our Plant Health Diagnosis Tool and FAQs here on our Plant Health Care page.