Garden Club of Cape Coral | Powdery mildew
So, last time you checked, which was a while ago, you had a great-looking shrub enhancing your landscape. However, you haven’t been paying much attention to it recently. By the time you finally take a stroll around your property, you find that the shrub is not looking so good. The once vibrant leaves have changed color, and the plant looks to be near demise.
When you investigate both the top and underside of the leaves, you notice that a white to grayish powder-like substance had taken hold on the great majority of the leaves. The culprit: powdery mildew, a fungal disease that can severely weaken a wide range of plants if left unattended.
The question is: Do you remove the entire plant? That could be one option, especially if you have similar shrubs in the vicinity which could easily become infected. Or, do you attempt to nurture the plant back to health in reparation for your neglect? I decided to choose the latter option.
Because the disease had gotten well out of hand, I began by putting on my trusty gloves, gathered up a trash can and began pruning the stems and branches of infected leaves. One, and then another, and then another, making certain the waste went in the can and not on the ground. I also gathered up leaves and branches that had already fallen and placed them in the can as well, because allowing infected debris to remain in the landscape is a no-no. After finishing, I wrapped the contents, discarded the entire mess very carefully and, then, disinfected my pruning shears.
As I looked at what remained of the shrub, I wondered if it would survive the severity of the cuts. I am glad to say it did, with a new flush of growth beginning within a few days.
As a measure to control further outbreaks of powdery mildew, I decided on a copper fungicide specific to the issue at hand, making certain to follow label directions for initial and follow-up applications. I began by spraying both sides of leaves on a calm evening. I wanted to avoid treating in the heat of the day to avoid burning leaves. Note: If your shrub produces flowers, avoid spraying directly on the blooms and when bees and other pollinators are active.
If you prefer homemade preventative measures for powdery mildew, you could experiment with a combination of 1 tablespoon baking soda to 1 gallon water plus a small amount of spreader-sticker, or a combination of milk and water (Thralls, 2019). Having never gone the route of either measure, I can’t say for certain how effective they are. However, should you use one of these remedies, keep in mind that just because something is touted as a natural remedy does not mean overuse is acceptable.
We all know that prevention is the best remedy. While you may not be able to stop mildew disease completely, you can maintain some semblance of control by, first and foremost, placing the right plant in the right place, doing your best to select plants that are disease-resistant when at all possible. Avoid overcrowding and water from the base of the plant, that is, if you, and not Mother Nature, are doing the watering. My plant receives supplemental watering from a soaker hose. Give sun-loving plants plenty of sunlight. And last, though certainly not least, keep an early eye out for issues and treat accordingly, using least-toxic measures as a start.
I know only too well when you neglect landscape plants, pests and diseases will find a way to sneak in. If I had been vigilant, I would have noticed that something was amiss and been able to treat the issue early on, thereby saving considerable time and money. But, as they say, hindsight is 20/20.
Until next time …remain vigilant and Happy Gardening!
Janetta Fox is a Lee County Master Gardener Volunteer and member of the Garden Club of Cape Coral. Visit us at gardenclubofcapecoral.com.