Fact Sheet 1999

Managing Volunteer Crabgrass Stands

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Introduction: All crabgrass is an annual. Crabgrass never lives through winter. Stands must be regenerated from seed each spring-summer season. That seed may be planted each season or supplied via planned-managed volunteer. One of the very desirable traits of crabgrass is that it can be managed for volunteer to limit planting expenses, time, and labor. By managing for volunteer, the plant mimics a perennial forage. This summary outlines the basic methods to accomplish that for the Red River variety and the natural or common types of crabgrass. The procedures are the same for all crabgrasses.

Two Important Characteristics: Crabgrass is indeterminate in growth. It makes vegetative growth, seed heads, and ripe seed simultaneously all summer. In southern Oklahoma this may occur from June to November in a good, long season. This allows for multiple opportunities to manage for seed-drop to create the seedbank for volunteer.

Crabgrass also responds to proper tillage (renovation). Proper tillage, when possible to do, increases earliness of crabgrass forage volume, general vigor of summer growth, and total season forage production. These two important characteristics properly considered and used are a great benefit in managing for volunteer stands. Crabgrass can also be used in numerous no-till forage situations.

How Is Crabgrass Being Grown? Crabgrass is usually grown for pasture, hay, and conservation in some manner. Double cropping with winter pasture is most common. This usually allows a time in fall and/or spring to till for volunteer management. Crabgrass may also be grown in mixtures with numerous other forages. Almost all of these situations come down to using the forage crop as: 1) Grazing, or 2) Hay. Management guidelines for creating a seed drop for a seed-bank on and in the soil will be outlined from these perspectives as follows

Managing For Volunteer Stands In Grazing Situations

In southern Oklahoma early-developed crabgrass pasture starts coming to seedheads in June. In a grazing case, seedheads continue to form all summer to fall. We highly recommend rotational grazing as the recovery period can be managed to allow adequate seed drops for the volunteer management.

With continuous grazing at a stocking rate to allow a little surplus forage by mid-term, the crabgrass will set seedheads and seed around manure and urine piles and closer to the ground otherwise. However, be certain to specifically check across the pasture to be sure there is seed drop everywhere.

With rotational grazing, the grazier can control recovery periods to allow some mature seed to develop across each paddock during some time of summer. I prefer to start this process on some paddocks as early as seedheads began to form. Then as grazing rotations proceed, continue the process on additional paddocks until the seeddrop has occurred on all paddocks (see photos). Residue (stubble) height at end of grazing should be 3 to 6 inches. Recovery periods of 3 to 4 weeks are usually sufficient for seedhead development during good growing conditions.

In both cases above, if seed will readily thresh out or shatter in your hand about every 1 to 2 feet, that is enough seed to perpetuate volunteer stands (see photos). I like to get about teaspoonful of seed or more to each such spacing. More seed is ok. These shatterable seeds should be brown to gray-green in color. If seed mature very well, cattle consume them and much seed passes viable in the manure and that contributes to distribution and volunteer stands.

Managing For Volunteer Stands In Haying Situations

If an early, lush, crabgrass hay crop is taken before the crabgrass drops seed, be sure to manage for seed drop in the next regrowth.

Second and future regrowths come to seed readily. The choice is to harvest higher quality hay with fewer seedheads or to delay harvest to allow enough mature seed to shatter during the process of harvesting.

Again, if seed will readily thresh out or shatter in your hand every 1 to 2 feet, that is usually enough seed to perpetuate volunteer stands (see photos). I like to get about teaspoonful or more to each such spacing. More seed is ok. These shatterable seed should be brown to gray-green in color. As the hay is mowed, raked, and baled, seed will be shattered for creation of the seed-bank for future volunteer stands

An excellent technique is to leave seed-strips every 1 to 2 swaths. These strips mature much seed before the next cutting or grazing. When the next harvest is made, manage to leave the strips in a different pattern. Combining this idea with the above is a good method. These strips need to be only 6 to 12 inches wide.
Miscellaneous Comments

I have heard people say crabgrass cannot be grazed so short that it cannot make seed to volunteer. Wrong!

Seed research shows that over 10% of crabgrass seed can remain viable for two years buried in moist soil.

When tillage is done to manage crabgrass, do it shallow to prevent burying all seed to deep. And, never till too late in the spring season to destroy a new stand. Fifty percent or more of the stand comes from seed no deeper than inch.

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