If you have turf grass, grow lily-of-the-Valley, or shrub roses, you might be interested in the results of a wet summer on these plants. Let’s start with grass.
After walking around your yard, you may notice an orange powder collecting on your shoes. It is a fungal disease called turfgrass rust. To thrive, it requires cool, humid nights with heavy dew. The ground stayed hydrated this summer thanks to adequate rainfall. Once the nights cooled in late summer and early autumn, the conditions were perfect for turfgrass rust.
The good news is it won’t kill the grass, nor does it need to be treated. It is only noticeable after a wet summer, and finally, it doesn’t permanently stain clothes or shoes.
Lily-of-the- Valley growers might be concerned about their patch of plants because they might look like they’ve died or are severely stressed. They’re affected by another wet season problem called Botrytis elliptica, which first causes irregular flecks and brown spots, followed by the leaves turning brown and falling off after a cool, damp period. Although your Lily-of-the-Valley patch looks dead, the underground roots and rhizomes remain unaffected and will regrow next season.
Botrytis is a fungus that over-winters on the soil and plant debris, which means fall cleanup is important. Rake up and remove any debris, but don’t compost it. There are also some preventative measures available. As just mentioned, good sanitation is helpful. Also, try not to over-crowd the plants, which is hard since an established plot will fill in every open space with more rhizomes. Don’t over-fertilize them. In fact, I’ve found they get along quite nicely without any fertilizer. Finally, avoid overhead watering to keep the leaves dry.
My last observation concerns shrub roses sometimes referred to as Knock Out roses after the brand name that made them well known to gardeners and homeowners. Shrub roses usually have a large flush of blooms in late spring into early summer, followed by a lesser scattering of flowers the rest of the growing season. This year, the scattering was more of a constant array of color all summer into fall. I assume it was the abundance of rain, so when we went without natural rainfall for a couple of weeks, I watered them deeply with rainwater from my rain barrels, and blooms just kept coming.
I hope you are enjoying this extended growing season. If you run into a problem, give the Edgar County Extension Master Gardeners a call at 217-465-8585, or email klraymo2@illinois.edu.
Illinois Extension leads public outreach for University of Illinois by translating research into action plans that allow Illinois families, businesses, and community leaders to solve problems, make informed decisions, and adapt to changes and opportunities. Illinois Extension is part of the University of Illinois Urbana-Champaign College of Agricultural, Consumer and Environmental Sciences.