We have a variety of areas in our lawn where the wild strawberries are consistently killing our grass. Is there an organic way to control these? We have been fairly successful at tackling other weeds (Dandelions/Crab grass) by letting the grass grow longer and using pre-emergents, but this has been a bit out of control.
Apart from digging them by hand, either on your hands and knees or use one of the weed diggers available, for use when standing. Depending on your situation/location/size of lawn; would keeping chickens on the lawn be an option for you, they will scratch around and clear the lawn of everything including the grass for you to re seed later. Rake the lawn to comb the runners and then cut with mower very short. That will remove the easy bits and expose the rosettes of leaves for you to more easily target the plant for removal. If it's really bad and you wish to have a lush green sword do you want to go down the root of returfing? In which case, remove and compost the top layer, returf, and then once composted down, your previous top soil and turf, will be a more enriched top soil to be used as a top dressing (hopefully free of strawberry seeds).
Depending on how big your area is, vinegar (acetic acid) could be a option. You can test household vinegar in a small area to see how well it works; however, since wild strawberry is a perennial, you will probably need a concentration that's greater than the household 5%. (5% household vinegar works better for small, annual weeds.)
The stronger solutions will be labeled as herbicides - it's required by law to be labeled as such. Follow directions on the label.
- Vinegar solutions greater than 5% are considered hazardous and greater than 10% can burn your skin or cause serious damage to your eyes, so wear protection and follow the directions on the label.
- Spray it directly on the plants so that they are completely, I mean completely, saturated.
- The vinegar will kill the grass too. However, you can take a large plastic lid or plastic tablecloth or something similar with you to cover the grass where you might over-spray.
- Spray on a sunny, windless day. The hotter the day the better.
- Test a small area first to see if it works.
- If you want to increase the effectiveness of household vinegar, add salt: 1 cup/gallon vinegar. Keep in mind, a lot of salt in your soil will change the pH of the soil. (See the tip above.) You can also add 1 tablespoon dishsoap to help the salt and vinegar solution cling to the plant.
Purdue University https://hort.purdue.edu/ext/vinegar.html
University of Illinois Extension: https://web.extension.illinois.edu/cfiv/homeowners/070913.html