Before we moved to our current address, there had been a creek running through our yard. People have told us that it was a field with sedges, which I believe were common black sedges (Carex nigra). Just before we moved here, the city straightened the creek and laid concrete for better flow of the water. We filled in the land, and still the water came, so I created a mesic wetland on the west side. On the east side, I created a prairie.
One of the flowers I planted was queen of the prairie (Filipendula rubra). It always mildewed, and then went away.
Over the last 37 years, the sedges have come back, and the prairie now looks different. The queen of the prairie returned three years ago and is no longer mildewing.
I originally planted some cordgrass (Spartina pectinata), and eventually it went away — but it came back about three years ago. The tall ironweed (Vernonia gigantea) and swamp milkweed (Asclepias incarnata) are also back. Hopefully, the Culver’s root (Veronicastrum virginicum), turtlehead (Chelone glabra), mountain mint (Pycnanthemum virginianum), and boneset (Eupatorum perfoliatum) will stick around.
What is Powdery Mildew?
Powdery mildew is a powdery white coating that forms on the leaves and stems of some plants. I’ve had a problem with it on my queen of the prairie (Filipendula rubra) and bergamot (Monarda fistulosa) plants in my mesic prairie. Although the mildew does not typically kill perennial plants, it hinders photosynthesis.
Mildew is spread by spores generally carried by the wind and rain. It likes humid weather and thrives in wet conditions — not because it likes it wet — but because it finds crowded, overgrown plants and poor air circulation among them great conditions to cause havoc. Once the humidity of our hot summers dissipates, the spores tend to disappear, too. But they can overwinter on plants or plant debris and start the process all over.
Now that the weather has become more warm and rainy, I wonder what I will see in the future in our prairie.
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