Weedy Grasses

There is a lot of confusion about the types of weedy grasses that invade our lawns.  The weedy grass invasion happens throughout the year.  Several grassy weeds pose a continual problem for those who like that immaculately groomed weed-free turf lawn, and they appear seasonally.  Here is a brief rundown on the most common grassy weeds found in lawns in the West Texas area.

weedy grasses - crabgrass seedling

Crabgrass.

Crabgrass is the chameleon of the weedy grass family.  Depending on the environmental conditions, the soil conditions, and the growing conditions, it can take on various disguises.  Sometimes this makes it hard to identify among the several other weedy grasses that usually appear at the same time.

Crabgrass seedlings start life looking a bit like corn seedlings.  It will have wide leaf blades, which can be up to ¼ inch wide.   Most other turfgrasses and weedy grasses start as very narrow thin blades when they start.  The blades angle out from the stem, lying almost flat on the ground and at the same time, side shoots develop very quickly

weedy grasses - crabgrass with shoots and stems

Because crabgrass tends to lay low along the ground and because it propagates itself by rooting where the stolens come into contact with the bare ground, it is particularly tough to control.  This star pattern of development is easy to spot. 

The seed stalks of crabgrass can easily be mistaken for Bermuda grass seed heads.  They will be upright and have from 3 to 5 seed stalks with very small seeds. 

Crabgrass Control
weedy grasses - crabgrass seed stalks

The best method of controlling crabgrass and all the other grassy weeds is to engage in a systematic organic lawn care program.  By and large, weedy grasses look for bare open ground to take root.  A thick layer of turf established in healthy soil will prevent almost all weedy grasses from gaining a foothold.

If you already have crabgrass, you can start controlling it with spot spraying a vinegar solution directly on the crabgrass.  Vinegar may take several applications to eradicate the plant, but it will eventually be effective and will not damage your soil.  The crabgrass will die off with the first frost of the season.  Remove the dead plants.  An application of an organic pre-emergent in the spring, before April 1st, will prevent the seeds that have been dormant over the winter from sprouting.  Corn gluten meal can be effective for this application.  There are other organic products on the market to help control crabgrass, but take care that what you buy is organic and not one of the “organic friendly” or “organic-based” options that don’t meet the standards of a truly organic system.

Dallisgrass

weedy grasses - dallisgrass in bermuda
Dallisgrass showing bullseye pattern
weedy grasses - crabgrass in bermuda
crabgrass showing distinct CenterPoint

Dallisgrass and Crabgrass get misidentified regularly.  Compare the two pictures below.  Which is which?

Crabgrass is on the right.  Notice that it has a distinct center point with stolens and stems radiating from that center.   The Dallisgrass on the left shows the bullseye pattern that is common with mature Dallisgrass clumps.

The main difference in the two is that crabgrass is an annual and depends on dormant seeds sprouting each year in the spring.  Dallisgrass is a perennial and will return in the same spot each year from the roots.  It also sends out short rhizomes just below the soil surface, which results in the distinctive bullseye pattern. 

The identification of Dallisgrass is easier if there are seedheads on the plant.  Looking at the picture at the left, you can see the Dallisgrass seedhead compared to a crabgrass seedhead.  The dallisgrass seeds are heavier and appear much fuller than the crabgrass heads.  They also sprout from the main stem on a staggered pattern rather than branching from a single point like the crabgrass. 

weedy grasses - dallisgrass seed head

Dallisgrass is insidious.  Because it overwinters and has a very well established roots system that stores carbohydrates very efficiently, it is highly resistant to most herbicidal remedies, spot spraying with a vinegar solution can eventually eradicate this weed from your lawn, but it will take repeated applications.  The best method we have found is to dig out the whole plant, to get as much of the root mass as possible, and then filling the depression with compost.  You can reseed turf onto that area immediately for faster regeneration.

Rescue Grass

weedy grasses - rescue grass seed head

Rescue grass is probably the most prevalent weedy grass seen in most lawns in West Texas.  It is often misidentified as wild rye or winter rye.  Rescue grass is an annual grass that is considered an invasive species in Texas.  It is a relatively short-lived annual grass.

It is easily identified by the dropping rather flat seed head with large spiked seeds.   Rescue grass is a cool-season annual that returns each spring from seeds left dormant in the soil.  Because it doesn’t tolerate heat well, it usually dies out as the outside temperatures increase during the summer. 

Application of corn gluten meal as a pre-emergent in early spring can help prevent the return of rescue grass.   Since rescue grass has relatively shallow roots, it can be removed by hand easily.  Regular mowing of the lawn can aid in control by keeping the rescue grass cut before it can mature and produce seed.  A well managed organic turf system will do more for preventing rescue grass than any other management option.

Sandbur

weedy grasses - sandbur seed head

This plant has been the scourge of West Texas summers for kids.  One encounter with the spiked seeds on a barefoot leaves a lasting impression.  This invasive plant can be troublesome, not just from the spiny point of view.  In areas where the winter temperatures do not get below freezing for long periods, sandburs will act like perennials, coming back from the roots each year.  Because the spiny seeds spread easily, they also produce an abundance of new plants like an annual from seed sprouts each spring.  The seeds can lay dormant in the soil for several years, waiting until conditions are just right to sprout. 

Control of sandburs requires establishing a good organic system of turf management that builds carbon in the soil.  Applications of humates, dry molasses, and corn gluten meal will aid in this process.   Spraying the plants with a vinegar solution will work, but may take repeated applications.   Removal by hand is effective if done before the seed heads develop.  Because mature seed heads can lay dormant for years, we advise not to mow sandburs that already have seed heads established.  Remove the seedheads by hand and dispose of them before mowing.  Removal of the mature seed heads will prevent the spread of sandburs.  Applying corn gluten meal in the spring as a pre-emergent can also help prevent the seeds from sprouting.

Foxtail

weedy grasses - foxtail seed head

Foxtail is an annual grass that I have seen this year in more abundance than ever before.  It comes in several varieties, which can make identifying it hard.  The real give away is the dense, thick seedheads that look almost furry, hence the name foxtail.

The seed heads may stand upright or droop and may come in a variety of colors. 

The plant will grow in loose clumps or singly.  First, sprouts are usually close to the ground but then turn upward as the plant matures.  Foxtail can eventually reach heights of 3 ft if untended. 

Foxtail is an annual and reproduces each year from seed.  Keeping annual grass mowed before it can produce seed will eventually lead to control; however, seed blown or carried into your turn will always be a problem. 

This annual grass has a relatively small and shallow root system, which makes it easy to remove by hand.   Push hoes are also effective on large patches.  The application of corn gluten meal in the spring as a pre-emergent will help control the re-appearance of this weedy grass.

Links and Resources

For more information about organic gardening, lifestyles, and living, visit our website at West Texas Organic Gardening.

If you found the information here helpful, you might also find these articles on our website of interest.

The Vinegar Question

Weed and Feed – Don’t

Lawn’s – What?

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