Four crabgrass seed studies were conducted to characterize feed value, seed germination, and seed dormancy more definitively. Objectives were to obtain precise and practical information to help manage planted and volunteer stands.

The following summarizes the results.

Trial 1
Some wildlife managers in the southeastern United States suggest using crabgrass in mixture plantings to provide cover, nesting area, forage, and seed (grain) for various animals like quail, rabbits, and other ground dwellers. Rabbits and other wildlife graze the forage, and the seeds are among those eaten by quail, turkey, rabbits, and other wildlife. Deer sometimes bed in crabgrass pastures.

We have tested crabgrass seed for crude protein (CP) content, which averages about 12 percent, many times over the years. Until now, we never tested the seeds (in the hull) for other chemical quality parameters. Five commercial seed samples were analyzed for a wide range of chemical and feed value contents. Results are presented in Tables 1 and 2 and illustrate that crabgrass seeds can have substantial food value for wildlife as well as domestic livestock.

Trial 2
Many legume and grass seeds are available in coated forms on the commercial market. The coatings are variable, but they can provide a more flowable seed, a fungicide treatment, and a soil nutrient (starter fertilizer) supply as well as other benefits.

'Red River' crabgrass seed was coated by a commercial company (CelPril) with Apron-FL fungicide and a soil nutrient (1-7-4, N-P205-K2O). Two commercial laboratories tested the seed. In a replicated trial begun May 14, uncoated and coated seed were planted on an excellent seedbed. The pure live seed was planted on the basis of seed count; i.e., at three pounds of seed per acre, the same number was planted, regardless of seed size (coated versus uncoated). The uncoated seed was broadcast-planted at three pounds pure live seed per acre. Coated seed was planted at one and one-half and three pounds per acre in each broadcast and in seven-inch rows.

There were inconsistent differences in germination and dormant seed test results based upon coated or uncoated seed. Coating did not influence those seed characteristics. The initial plantings emerged to an acceptable pasture stand after one good rainfall during June 9-11, and readings were taken on June 30. There was not any consistent stand advantage to coated seed versus uncoated seed, which does not imply that results would be the same in other situations. Doubling the seeding rate of coated seed from one and one-half to three pounds increased stand density by 16 percent. Coated seed is more flowable and larger, thus easier for many producers to plant. This test suggests that there was not much advantage to coating crabgrass seed, but further related studies are necessary.

Trial 3
Common crabgrasses are annuals in the United States. All stands, whether planted or volunteer, must come from germinated seed each season. When a producer manages a stand for volunteer or seed harvest, he must know when the seed is ripe enough to produce shattered seed for the next volunteer stand's seed bank or be harvested at the proper time. Crabgrass is an indeterminate plant that never comes to head and ripens its seed only in succession, as do wheat and other crops. It can produce new tillers, seed stalks, seed heads, and ripe seed simultaneously throughout the growing season. A producer must make a judgment about adequate (relative percentage) seed ripeness. We assumed that green hard seed was mature enough physiologically to germinate well, but our assumption was not verified in trials. Seed with a range of maturities was sampled from pasture and harvested seed from the same area and tested to yield more precise results, enabling development of better, more accurate guidelines for seed-drop management of volunteer stands or maturity of harvested seed. Results are presented in Table 3.

The tabulated data readily show that any green to brown seed, hard to ripe, is physiologically mature enough to germinate well. Germination of green, hard seed was from 74 percent to 88 percent that of the best brown, ripe seed. However, green, small, soft seed was obviously immature, and germination was only 55 percent that of the best seed but, surprisingly, it still was mature enough physiologically to produce 44 percent germination. We would expect those seed to produce slow-developing stands of weak seedlings. The following guidelines are appropriate: (1) for volunteer stands of crabgrass, in either pastures or hay meadows, manage use to allow development of about 1/4 to 1/2 teaspoonful or more of easily hand-threshed green or brown seed per handful of heads about every 1 to 3 feet across the area, and include shattered brown seed on the soil surface (proper management afterward will ensure good stands); (2) for seed harvests, one third or more of the major portion of the seed crop should be green or brown seed easily hand-threshed, as discussed above.

Trial 4
Some crabgrass planters thought that seed planted long before germination would have earlier, more-rapid germination and stand development during favorable temperature, light, and moisture conditions in the spring because cold/warm and wet/dry cycles might break more seeds' dormancy and hasten germination of germinable seeds. To test this hypothesis, newly harvested seed was used and subjected to the three treatments presented in Table 4. Seed in the barn and associated with the soil was in small white cloth bags so it could be influenced readily by temperature and moisture. The seed subjected to soil storage endured natural temperature and moisture fluctuations for 74 days from Feb. 1 to April 14. There was 1.2 inches of rain the first month, 5.3 the second, and none the last 14 days. High/low temperature ranges per month were 58/39, 60/41, and 72/49 °F.

The data in Table 4 show a slight germination improvement of 15 percent to 17 percent with soil storage; i.e., on the surface or 0.5 inch deep under natural conditions. Although such a result was an improvement, it was slight. However, in this case, even the barn-stored fresh seed exhibited 90 percent germination of all live seed.

This hypothesis needs more testing using seed with a higher dormancy rate.

It seems that storage duration is as important as temperature and moisture fluctuation to break seed dormancy. Some other seed lots stored in barns may exhibit about 50 percent germination the first year and over 90 percent the second.

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