University of Maryland Extension

Fighting Crabgrass Begins in the Fall

Image Credit: 
K. Mathias, University of Maryland

Fall is a time for winding down. The season is coming to a final close as we harvest the last of the crops. Outdoor recreation is coming to a close—whether we like it or not!—as our daylight hours get fewer and fewer. And with the first few frosts now behind us, weeds are winding down, too. If you are concerned with pasture or hayfield management like I am, you will have noticed that some of the peskiest weeds have disappeared. Crabgrass is one that stands out in my mind, especially because of the large bare patches it has recently left behind. Unless you’ve been extremely diligent with your mowing regimen this season and also very lucky, that crabgrass sowed at least a few seeds in your soil and will reappear as soon as environmental conditions are right in the spring.

Why be concerned with crabgrass? After all, it’s not toxic. It’s palatable, and it can actually be very highly nutritious. It can also be relatively high yielding. However, those bare patches that crabgrass leaves after one or two fall frosts will provide the perfect opportunity for more weeds to encroach in the spring. A vigorous established stand can prevent weeds from taking hold, but a bare spot provides a clear view to the sun and gives new weeds an opportunity to take hold. Crabgrass is one of the worst weeds in my mind because it opens the door for more and more weeds to start growing.

But don’t despair! There are some actions you can take now to work toward a more weed-free pasture in 2014. First and foremost, that includes dealing with those bare spots before spring. Plan to overseed your affected fields in late winter so that there is grass seed in the soil to compete with the weed seed that is also there. The freeze-thaw cycle and adequate rainfall during this time period helps seed get into the ground without requiring the use of a seed drill. You can either broadcast over the entire field or simply scatter some seed in the bare patches.

You can also turn animals out into the newly seeded field as the action of trodding hooves helps to increase seed to soil contact. If you choose to do this, however, remember to keep animals off of pastures when the ground is saturated. In muddy situations, hooves can do more damage than good. It’s also important to remove animals from the pasture as soon as the new grass germinates and to keep them off the pasture until it becomes well-established. If animals are allowed to graze new plants before they develop a strong root system, the delicate plants will die and your hard work will be for naught.

You can overseed either with your cool season pasture species of choice or a small grain like oats. If you winter seed with an annual small grain, you may also need to seed in late summer with a perennial forage species, but you will get bare spot protection earlier in the season. Oats will germinate when the soil is about 40 degrees F, but Tall Fescue won’t appear until soil temperature reaches about 60 degrees F. Earlier shading of bare spots can make a big difference in terms of weed encroachment.

Consider the season of frost as nature’s gift to the crabgrass warrior. The control has been taken care of for you, saving you the expense and labor of controlling it yourself. Take this opportunity to give desired species the competitive edge and give yourself a head start on controlling pasture weeds in 2014.

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