Weeding in the time of Coronavirus

By Irene Shonle,  El Paso County Extension

At the time of writing this blog, the entire state of Colorado is under stay-at-home orders due to the Coronavirus.  It’s a scary, uncertain time, and it is creating a lot of anxiety for most people.

I have the perfect activity to help.  It’s something you can do while house-bound (you are allowed to be in your yard), releases all kinds of anxious energy, gets you out into the sunshine, and gets your hands dirty (the latter two are proven mood-lifters).

It is dealing with your winter annual weeds.  Weeds that fall into this category include kochia, cheat grass, prickly lettuce, henbit, redstem filaree, and many of the mustards (blue mustard, flixweed, shepherd’s purse, etc).  You do need to learn to recognize these weeds when they are first emerging (especially if you have sown any desirable seeds) so you can treat the right plants. While the Extension offices are mostly closed due to the Coronavirus, you can still email pictures in for identification, or you might find your weeds pictured in one of these two guides: https://agronomy.unl.edu/documents/Identification%20of%20Winter%20Weeds.pdf or here: https://s3.wp.wsu.edu/uploads/sites/2079/2015/06/Weed-Seedling-Identificaiton-Guide-Montana-Ext.pdf

Kochia seedlings

Right now is the perfect time to get out there - - winter annual weeds are just emerging from the soil, and are very easy to kill with just a hoe, or even hand-pulling, depending on how many you have to deal with.  At this stage of growth, they have almost no root system, and require a minimum of effort.  Plus, the soil is probably moist after the winter precipitation, which makes it easy to work. Also, the winter annual weeds will mature and set seed sooner than summer annual weeds, so they are good to prioritize.

So easy to kill those little tender seedlings (kochia)

It will be much harder to deal with any of these plants once they have fully grown, have established root systems, and tougher stems. And if you let them get to the point where they are about to drop seed, then you will have to pull and bag the weeds. So much easier to deal with them now.

Mature kochia (missouristate.edu)

I have recently moved to a house on 1/3 of an acre, mostly covered with kochia, cheat grass and bindweed, so I have lots of therapeutic activity ahead of me. I have thickets of kochia coming up from years of plants dumping their seeds into the soil.

One of the things I like to think about when I am working on winter annual weeds is how much future seed I am keeping from getting into my soil seed bank. For example, one cheat grass plant can produce 500 seeds, and one kochia can produce over 14,000 seeds.  So even pulling a couple of plants could prevent thousands of future weeds.  It’s even better than the return on investment with mending clothes (remember that old saying “a stitch in time saves nine”)? And one swipe of the hoe, I am preventing hundreds of thousands!  Why, I am a veritable super hero.

Many winter annual weed seeds fortunately do not remain viable for very long; often just 1-2 years in the soil. This means that if you keep any of your current crop of weed seeds from maturing to the stage where it can set seed, you will actually be able to clear your yard of these weeds with just a couple years of diligent effort.

I wish I could say the same of bindweed!

Weed of the Moment: Kochia

Posted by: Tony Koski, Extension Turfgrass Specialist

Kochia (ko-sha) (Kochia scoparia) is a very common weed found everywhere in Colorado. It can be found in rangeland, pasture, gardens, ditches and on small acreages--essentially anywhere with disturbed soils. Kochia is a native of Asia and was introduced from Europe. As a summer annual, it begins germination in early spring. With its fuzzy gray leaves, as a small plant it's not unattractive, since it forms a dense mat on bare soils. [Note: I once was asked by a homeowner if she could have a kochia lawn, since she thought it was so pretty.]

Young kochia just after germination.

As summer progresses, the plant grows taller and looks like a gangly teenager, until it breaks off in fall, turning into tumbleweeds as large as 6 feet tall. And that's how the seeds disperse. Thousands and thousands of 'em. If you've ever driven on E470 to the airport, you've likely smashed one into smithereens.

Tumbleweed. It's a big 'un!

If you have kochia in your landscape, pull it or control it while it's young. It's much easier to control as a young seedling. Plants have a very shallow taproot and can easily be pulled or hoed. A thick layer of mulch can be very effective in helping control kochia. Kochia can be controlled using a non-selective herbicide like glyphosate (Roundup) when it is young (less than 12 inches tall); mature kochia is very resistant to glyphosate and just about any other herbicide. When using glyphosate for kochia control, complete coverage of the weeds is essential or you will have poor results. Remember to apply all herbicides according to the label. Focus your efforts on cultural conditions and management. It's rare to have kochia in the lawn, unless you have thin, bare areas.

Invasion of the tumbleweeds! A backyard in Pueblo.