COLUMBIA CITY, Ind. — Maybe you have been saying for years, “One of these years, I need to control the weeds in my lawn.” A worthy goal. Now is the time to assess what is there, because weeds are, well, growing like weeds!
Before starting, you may want to do some deep thinking about what your goals are. Are you after a pristine monoculture of beautiful, green grass? Or, can you put up with a few weeds? Keep in mind that if you are after the lawn of envy in the neighborhood, it will take considerable time and money to achieve. You will also need equipment, knowledge and skill if you plan to do it yourself.
One reason you need to assess what weeds are in your lawn is because you may have one, two or three categories of weeds: grass weeds, broadleaf weeds, or sedges. The management required for each category is somewhat different.
First of all, grass weeds. The poster child of grassy weeds is probably crabgrass. Crabgrass is what we call a summer annual weed. In other words, seeds sprout in the spring, it grows and produces seed through the year, and completely dies before winter. So, crabgrass is not a perennial plant like our lawn grass is. It has a broader leaf than most normal lawn grasses, and a seed head with 3-5 spikes clustered at the top of stems. The seed head spikes are easy to see now, and if you have them, you can bet you’ll have crabgrass again next year. Crabgrass herbicides available to homeowners are primarily “preventer” products, meaning that they need to be in place before crabgrass emerges. These pre-emergence herbicides must be applied early in the spring to be effective (best from March 1 to about mid-April in northern Indiana) – at least a week or two prior to germination of crabgrass. Post-emergence herbicide products are available and are most effective on small crabgrass plants, but the products are very difficult to use effectively by most homeowners. Post-emergence treatment is probably best left to professionals. Bottom line – nothing to do now, wait until early spring.
Other grassy weeds may include annual bluegrass, quackgrass, or zoysiagrass. Note that annual bluegrass is a weed, while Kentucky bluegrass is a desired turf grass (a perennial plant).
Broadleaf weeds are easy to spot because they simply don’t look like grass. Most people probably have white clover in their lawn. Who hasn’t gone looking for a 4-leaf clover as a kid? Many other common broadleaves may be present. Fall is a great time to control broadleaf weeds with selective herbicides.
The Purdue Extension publication, Control of Broadleaf Weeds in Control of Broadleaf Weeds in Home Lawns, states: “The best time to apply a general-purpose broadleaf herbicide is mid-September to early November. The fall is the best time to control perennial broadleaf weeds such as dandelion, plantain, and clover. Going into winter these weeds are storing energy reserves in stems and roots. Thus the herbicide will enter the plant and travel to these plant parts with the food reserves, thereby giving a complete kill of the weed. The second best time is in the late spring or early summer period after the weeds have ﬂowered.”
Finally, the sedge we worry most about is yellow nutsedge. It may be thriving in a wet area, but it can be found in other areas, and it will grow well in summer heat when grass will struggle. It looks like a grass, but will not be affected by grass herbicides because it’s not a grass. Yellow nutsedge will typically have a lighter green color, and is probably going to seed right now. To confirm you have yellow nutsedge, feel the stem. It has a triangle-shaped cross section. You may have heard the saying, “Sedges have edges.” Late spring/early summer (when it is young and actively growing) is the ideal time to control yellow nutsedge, and professional help may be needed. For homeowners, hand-pulling or digging may be your best option, and you won’t get it all the first time. You can count on re-growth from underground plant structures that remain in the soil.
To help you identify the weeds in your lawn, access a Purdue Extension turfgrass website in which several “weed of the month” selections are included, at https://turf.purdue.edu/weedofthemonth.html. Additionally, search for Purdue Extension publications on control of crabgrass, broadleaf weeds, or yellow nutsedge at https://mdc.itap.purdue.edu/.
— John E. Woodmansee, Purdue Extension Educator, Agriculture/Natural Resources
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