Sustainably Reducing Weeds and Pests from your Lawn

During the summer months, your lawn needs more attention than any other time of the year.  With cool-season grasses, like Kentucky bluegrass and fine fescue, the heat of the summer can be very stressful and weeds will often encroach in this situation.  For most homeowners, the tendency is to search for the right jug of herbicide to control the problem.  This is a reactionary approach and only a short term solution. Taking some time to learn more about the source of weeds could lessen the amount of chemicals needed for your lawn in the future.

“Good turf is your best sustainable defense against weeds,” said Sam Bauer, University of Minnesota Extension Educator in Turfgrass Science. “It’s all about the right species, in the right place, with the right conditions.”

Properly maintaining a healthy lawn will reduce the likelihood of weeds, diseases and insects entering the environment. Bauer said that compacted soils, moist shade, and flooded soils with the recent onslaught of rain have been the most common problems with lawns in Minnesota. Lawns grown on compacted soils typically become invaded with weeds like annual bluegrass, chickweeds, knotweed, and prostate spurge.

Aerating compacted lawns can help reduce the encroachment weeds that thrive in compacted soils and will also benefit the overall health of the lawn. Aeration will allow the soil to drain more effectively and grass plants will better utilize water and nutrients.

Moist shade is another common lawn problem in Minnesota being the possible source of weeds such as wild violet and ground ivy (i.e. creeping Charlie).

Using Herbicides

In an ideal world, all our lawns would be under perfect conditions to prevent the spread of weeds, but sometimes an herbicide is necessary to keep weeds at a minimum. There are several options to treat your lawn in the most environmentally-friendly manner.

The first step to using herbicides is to always follow the directions on the label exactly as they are printed.  It’s important to protect yourself and the environment by following the proper safety procedures when applying the herbicide.

For those looking for organic perennial grassy weed control options, for control of weeds like quackgrass or smooth brome, Bauer recommends using a vinegar acetic acid or pelargonic acid-based herbicides. It should be noted that these organic acid-based herbicides are non-selective and will kill most green plants in your lawn, so it is best to spot treat weeds and not overuse the herbicide.  These herbicides are burn down products and will only kill the foliage, not the roots, so the weeds will continue to grow back every so often.

Bauer said in his new Living Lab, Alternative Turfgrass Maintenance, he is planning to investigate biological and natural alternatives to synthetic herbicides and pesticides. One of those natural herbicides is available for purchase in garden stores. The Fiesta Turf Weed Killer is a selective broadleaf herbicide based on the micronutrient Iron.  This product has shown to be very effective.

Another herbicide Bauer is investigating in his new living lab is composed of live fungi.  Bauer notes that we will start to see more biological products on the marketplace in the future.

Overall, the less pesticide we can use on our lawns, the better. Some chemicals can also have a dangerous effect on pollinators, including honey bees, so it is best to not overuse pesticides in our lawns and gardens because it could contribute to their decline.

Remember, starting with a healthy lawn will reduce our need to use herbicides in our lawns.

Using Insecticides

Japanese beetle grubs are the most common insect pests of lawns in the Twin Cities area. They are usually attracted to moist soil and eat the roots of plants in gardens and lawns.

One natural alternative pesticide for killing Japanese beetles is the nematode. Nematode sprays are usually available for order through garden catalogs. Watering them down into the soil and keeping it moist for at least a week can  reduce the amount of Japanese beetle grubs.

The synthetic insecticides will do the best job of controlling Japanese beetle grubs, and chlorantraniliprole (Scott’s GrubEx) is a very effective option with low toxicity.