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Powdery Mildew Info / Symptoms:

Do your Ninebark, Peony or other dense-leaves shrubs have white stuff on their leaves? If so, you most likely have a fungal disease called Powdery Mildew.

Powdery Mildew is a fungal disease that is commonly found on Ninebark, Bee Balm, and other densely-leaved deciduous plants, especially when it is cool and wet. The disease is fairly cosmetic and tends to not hurt the overall plant health, unless left untreated for many seasons. However, it is still recommended to treat for it when your plants begin to show symptoms, in order to avoid long term damage.

If you notice any of these symptoms on your tree or shrub, send us a photo or bring in a sample for proper diagnosis.

Control Methods:

To treat for Powdery Mildew, you will want to start by trimming the inside of your plant to allow more airflow. You can also cut back any infected portions. You will want to coat the entirety of the plant with a systemic fungicide every 10-14 days as needed (typically 2 applications is sufficient).
The systemic fungicide we recommend is Bonide’s Infuse.
It is also important when dealing with any shrub to make sure they are in good health by fertilizing them in the spring. Fertilizers like Espoma’s Plant-tone can be applied to almost every tree and shrub, in order to help them fight off disease and to promote good growth.