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.
