Shining Geranium (Geranium lucidum) on Mar 24, 2024
Submitter has sample
Description of specimen
A roughly 15x10 foot patch appeared over the winter in the highest area of our backyard. This was a small native wildflower patch with some Russian Comfrey Bocking 14 about 1' wide and then lawn. It's a bit shady compared to the rest of our yard which is full sun. It didn't come in on the slope along the retaining wall or the lower portion of our backyard. We can see more in our neighbor's yard (chain link fence) along with Himalayan blackberry we try to keep out of our yard. I haven't seen this weed in our yard before and I weed over there regularly because of the Himalayan blackberry as it's right next to my son's swing set and I don't want him stepping on thorns. This patch is dense and has taken out the lawn and wildflowers in the area. The two huckleberry bushes we have are still there and I see at least two Russian Comfrey coming out of dormancy but everything else appears gone. This is a partially shaded area of our yard. This is in the upper area of our backyard. We have a retaining wall that divides the yard half. The weed is only in the high area, it's not on the slope along the retaining wall or in the lower area in the yard. I don't see it elsewhere in the lawn or in the garden beds on the far side of the lawn.
There is also a smaller patch in the very front of our yard, in an area about 8x10 feet wide. That side of our yard has a tiered retaining wall and I can only find it in the front tier (the 8x10 area). Unlike the backyard, it has not completely taken over. Native strawberry is still in the area at roughly equal density. The other plants die back each fall and haven't come out of dormancy yet, though the native onions should soon. I also have not need this weed in that area as well. It's on the same side of the house as the patch in the backyard. I would consider this area full sun.
Photos:
Two are of the weed, both at edges of the patch. One is the north-west edge of the patch where it's growing densely. The other is the southern edge where it's mixing with the remaining lawn. The red stems aren't easily seen in the photos but when I manually pulled several, you could see very red stems. Third picture is to give you an idea of the size. The patch width is from the chin link fence to the far edge of the play structure, then is mixes with lawn until petering out. It covers the whole length of that side of the yard.
For control you'll want to do your best to not move the seeds around on equipment, shoes and clothing. For the areas you describe you can manually remove before they go to seed while the soil is still moist. Try to get as much root as possible. There will be a considerable seed bank in the soil, so expect to be working on this into the future. If you are open to herbicide use you will want to use a broadleaf selective in the grassy areas to not kill the grass. Getting other vegetation to grow after removal will provide some competition to reduce new germination.
More information can be found at the SWCD website. https://tualatinswcd.org/species/shiny-geranium/
Keith Nasman
March 27, 2024, 5:42 a.m.