Now is the time to control weeds and grasses

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There is very little crabgrass in this part of the world; however, Wyoming does have cheat grass and annual foxtail. Annual grasses come from seed every year. These grassy weeds can take over in the lawn. They grow rapidly during the spring as the grass produces seed. The plant dies in July or August in Wyoming and the seed lies dormant until the following spring. The main annual grasses we need to control are annual blue grass, green foxtail and downy brome or cheat grass, which we see showing up later in March.

Quack grass is another grassy weed in lawns, but it is a perennial grass with hollow stems and wheat-like spikes growing at the tips of the stems.

The narrow leaf blades are bluish green and rough on the upper surface. A pair of “claws” occurs at the junction of the blade and the stem. The root system is very fibrous and can grow quite deep.

This grass can grow quite tall if not mowed. Quack grass can spread by seed or by its extensive root system.
To control annual grasses one can try to pull it or use pre-emergence (before a plant germinates from seed) or post-emergence (after plants germinate from seed) herbicides. Liquid forms are mixed with water and are sprayed on. Dry forms would be administered with a fertilizer spreader. Generally, dry mixes are found with brand name fertilizer mixes and are labeled for crabgrass control and lawn fertilization. This type of control can also help with some other types of annual weeds such as black medic and dandelions. If you keep annual grasses/weeds from going to seed for at least two years that should eliminate most of the problem, and this helps eliminate those pesky blown in weeds.

On any warm day in March, the sooner the better, is the time to apply a pre-emergence herbicide to control annual weeds. Once the ground warms up and the frost leaves the annuals will start to germinate. The advantage of most pre-emergence herbicides is they control a wide range of weeds, which germinate from seed.

The other advantage of applying herbicides this time of year is it less likely to damage other plants. There are some pre-emergence herbicides, which will work in the garden and flower beds. There are several companies such as Bayer and Spectracide, which offer good products; be careful and read the directions.
Controlling quack grass or other non-desirable perennial grasses is another matter. The only effective control would be a non-selective herbicide such as Round-Up. The problem with this would be the brown spots left in a lawn. Use a small container such as an old paint can, add Round-Up (there are other products made by different companies using the same chemical (glyphosate) but with their own brand name), and use a disposable foam paintbrush to paint it on the undesirable grasses.

This can be time consuming but will not leave quite as big brown spots in a lawn as spraying would. This technique can also work in flowerbeds and gardens, since there is no residual with glyphosate.
If using a sprayer or spray bottle try keeping it close to the ground to avoid killing desirable plants.
Remember on these warm spring days to drag the hose out and water all perennial plants. As long as the ground is not frozen, the water will soak in and give them some needed moisture.

Trade or brand names used in this publication are used only for the purpose of educational information.
The information given herein is supplied with the understanding that no discrimination is intended, and no endorsement information of products by the University of Wyoming Extension is implied.
Nor does it imply approval of products to the exclusion of others, which may also be suitable. The University of Wyoming is an equal opportunity/affirmative action institution.

Scott Hininger is with the Sheridan County Extension office.

By |March 30th, 2013|

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