sick moneywort groundcover
We live in Kensington. Our yard is part sunny, part shade. We planted moneywort as a groundcover a few years ago. The firts two years I weeded the whole yard to manually remove moss, as it was competing with the moneywort, which then grew nicely and gave a good coverage for a year. Then the middle of last summer, on the sunniest part of the yard it started to turn brown, so we thought it might be too dry. It partially improved with regular watering. This spring it started to grow nicely over the whole yard, but now it is dying out on a much larger area and more severely. I find stems of it that still has leaves on, but separated near the base, many leaves partially eaten, and many brown, dried stems and leaves. Even the weeds seem to have chewed up leaves. It still looks reasonably well in the most shaded parts of the yard. I do see a lot of brown beetles in and on the ground. Can you help? Can we still save the groundcover, or we need to get something else? Thank you very much.
This species is not known to have any serious pest or disease issues. Our plant pathologist looked at your photos and thought web blight might be a possibility because of the heat and humidity. Have you noticed any fine tan webbing around the leaves and stems? https://extension.umd.edu/hgic/topics/rhizoctonia-web-blight
We do not recommend this plant as a groundcover because it has become an in invasive species in some natural areas. It prefers consistently moist, but not soggy soil and likes some afternoon shade. It does not do well in hot, direct afternoon sun. We are not aware of specific insect pests that are a problem of these plants. There are a number of different types of ground beetles that are chewers but we would not recommend an insecticide. Many ground-dwelling beetles and other insects are beneficial.
For whatever it's worth, mosses are native and can make a suitable and beautiful groundcover as a lawn alternative. If moss has grown well in this location in the past, you might want to reconsider it as a groundcover. See Lawn Moss: Friend or Foe? https://www.pubs.ext.vt.edu/content/dam/pubs_ext_vt_edu/430/430-536/430-536_pdf.pdf