Figure 1. Midsummer crabgrass development from December (right) and February (left) broadcast overseeding into graze-out cereal rye and annual ryegrass

Figure 2. Late summer crabgrass development on all good broadcast crabgrass plantings after graze-out rye-ryegrass

Figure 3. Second season crabgrass from a February broadcast overseeding into cereal rye and annual ryegrass two winters before

Figure 4. Crabgrass-winter pasture double crop initiated by broadcasting crabgrass seed into graze-out small grains or ryegrass, or cool season annual winter grasses to be hayed or taken for grain.

An adaptation of this approach is to grow an annual winter forage, plow it as early as feasible, establish a good seedbed, and plant the crabgrass.

A third lower-input approach is to broadcast crabgrass seed into a stand of wheat, cereal rye, annual ryegrass, legumes, or similar forage, and let it develop as the season progresses to summer. Grazing stock then usually tread in the seed, except when the winter wheat or rye is used only for grain or hay. The agronomics are imperfect but save time, labor, and equipment and prevent erosion. The crabgrass stand usually is good, but early growth is slower than that from an excellent seedbed planting. The method fails if (1) the area is pugged in wet weather and the crabgrass seed is trodden too deeply, (2) there is too much lodged residue, or (3) the seedlings are trampled after they emerge.

Over the years, many people have asked us how early crabgrass should be broadcast seeded. A February planting with the winter crop's nitrogen topdressing works well. However, to address this question in more detail, we tested the date of broadcast seeding on the subsequent crabgrass stand percentage and production success.

The winter crop was 'Maton' cereal rye and 'Marshall' annual ryegrass planted on October 1. 'Red River' crabgrass was broadcast seeded into the rye-ryegrass stand on October 9, December 9, February 19, and April 7. The crabgrass was planted at 2 pounds of pure live seed per acre in a dry sand and crabgrass seed mix to get good flow and distribution. I now prefer to use 3 pounds of pure live seed per acre to attain quicker, thicker early stands in this syndrome, but both rates are successful.

The winter crop was fertilized, so the crabgrass planting was done without fertilization. However, on June 23 after runners formed, 50 pounds of actual nitrogen was put on the crabgrass to encourage stolon (runner) cover and produce moderate forage quantities the first year. If we had applied 100 pounds of actual nitrogen per acre, yields likely would have been about 1,300 pounds more per acre. The crabgrass seed was trodden in during the usual grazing of the cereal rye and ryegrass mixture. The earlier plantings, of course, got more treading, but all plantings were well trodden and we controlled the depth.

There was some indication that October was too early a planting date. Plants that germinated in late summer died at frost, and there was some seed loss via treading and rotting before spring.

Winter crops must be kept well grazed as the crabgrass seed germinates and early growth begins. We had a problem with too much grass and too few cattle. The extra ryegrass was mowed June 22 after the early crabgrass started developing runners.

We took readings in the plantings from May through August of the first year and after crabgrass stand development the second year (table 1).

A quick way to evaluate relative stand percentages is to walk across the area in question. Record a hit anytime you step on the forage in question and a miss when you step on bare ground or other nontarget items. Determine the percentage of hits relative to your total steps to find the stand percentage. It's easy and reasonably accurate.

The October, December, and February plantings started emerging first. However, by the time the crabgrass had produced a fair to good stand and some runners, the December, February, and April plantings were nearly identical to the first plantings (figures 1, 2, and 3) and were rated good by late June to early July. For broadcasting crabgrass into graze-out winter pasture, late February is better than April.

The first year, good stands were about 75 percent established by July 15, which is later than usual for crabgrass plantings in wheat and rye. Annual ryegrass retards early development of crabgrass because it grows until about June 15, or about six to eight weeks into the crabgrass season, and uses the spring moisture, shades the soil, and keeps the surface cooler. Annual ryegrass may be temporarily allelopathic (toxic) to emerging crabgrass. Crabgrass cropped with 'Bonel' cereal rye can produce an excellent pasture by mid-June. All plantings produced superb crabgrass stands by volunteer the second year (figure 4).

These plantings were made on a fine sandy loam soil. A crabgrass double crop started with the above method is best on sandy soils, intermediate on loams, and worst on clay loam soils. However, the stands can be successful on all three soil types.

The crabgrass from all four trials was harvested for dry-weight forage yields on August 11. The forage yields and projected beef yield per acre from each are presented in table 2. These data show only early production trends and yields. We did not fertilize and manage for upper-level yields.

First-year yields, even with excessive ryegrass residue, can be acceptable. Only 50 pounds of nitrogen was applied to the crabgrass pasture, so a yield of only 1 to 1 1/2 tons of forage per acre is expected.

1. use cereal rye or wheat, if feasible, for the first year;
2. broadcast 2 to 3 pounds of pure live seed per acre (3 pounds preferred) in a fertilizer or other flowable mix;
3. broadcast from February through April, but as late as possible;
4. tread in by using the spring forage to reduce the overstory and competition from the winter grass, allowing sunlight to reach the soil and causing earlier soil warming and crabgrass germination and growth (wheat grain producers have limited tread-in choice);
5. topdress the young crabgrass with 50 to 100 pounds of actual nitrogen per acre after plants are beyond the five-leaf stage and are forming tillers or runners (topdressing too early can damage very young stands);
6. use rotational grazing as usual after the main stand reaches 6 to 8 inches tall and manage for seed production for the next year's volunteer stand;
7. make hay from good stands after they are about 18 inches tall and leave a 3- to 6-inch stubble.