Most acres of tall fescue harvested for seed in Missouri are also used for hay or grazing at some point in the year. While this is a good way to maximize total returns from tall fescue, it often results in lower seed yields than if managed primarily for seed. For highest seed yields, tall fescue should be seeded thinly in rows and managed like other row crops. If grown like a row crop, seed yields can exceed 1,000 lb/acre in Missouri in good years. However, this is type of production is seldom done in Missouri, where the seed crop is secondary to the forage production.
Two management practices are of primary importance for producing high seed yields. They are: 1) removal existing forage (aftermath) in the summer prior seed harvest the next year, and 2) the application of nitrogen fertilizer during late summer and again winter.
The summer before a seed crop is desired, the stubble should be clipped, grazed or hayed to a height of 3 to 4 inches in July or August. If the fescue was not harvested for seed the previous year and is intended for seed the next, clipping or grazing should be done by mid-August. If the forage is over mature, it may be impossible to get livestock to consume the forage evenly. In this case, clipping the field after livestock are removed is best. If seed is to be grown on the same field for multiple years, the removal of the aftermath should be done immediately following seed harvest.
Removing the forage is necessary for the development of next year's seed tillers. These tillers develop during the fall and early winter, and they require direct light. So removing the forage permits sunlight to penetrate the plant canopy and stimulate tiller growth. Failure to clip or graze the forage to a stubble height of 3 or 4 inches may reduce the following year's seed crop by as much as 30 percent. The new growth that occurs in the autumn can be grazed lightly but should not be overgrazed.
Whereas summer clipping determines the number of tillers and seed stalks for the next seed crop, proper nitrogen fertilization determines the number of individual seed in the seedheads. In other words, nitrogen is primarily responsible for how well the seedheads "fill." If used only for seed, 30 to 40 lb/acre of N should be applied in late summer to allow for proper tiller development, followed by a topdressing of 60 to 90 lbs of nitrogen during January. Timing of winter nitrogen applications affects seed yields. Nitrogen applied in the early fall or late summer may not be available at the time it is needed in spring; it may be have been metabolized by fall growth. Nitrogen applied too late in the winter (often as early as Feb. 1 in Southern Missouri) causes lodging and excessive leaf growth instead of heavier seedheads.
In Missouri, determining the proper amount of nitrogen for a seed crop is often complicated by the applications nitrogen during late summer nitrogen (August); such applications are often applied to encourage fall growth for winter grazing. Some additional nitrogen should be applied in December or January for seed production, but the amount will depend upon the amount applied in the late summer or early fall (August-September), the amount of leafy fall growth, the grazing intensity, the amount of clover present, the rainfall before freezing, and a few other factors. A rule of thumb is that if no nitrogen was fall applied, 70 to 100 lb/acre should be topdressed during the winter; if 50 or 60 lb/acre was used in the fall, then use 50 to 80 lbs in the winter.
Phosphorus and potassium levels should be maintained at least in the medium range. On pure tall fescue stands the pH should be maintained above a pH of 5.5.
Since most of the tall fescue seed fields in Missouri are grazed during the fall or winter, cattle management becomes an important factor in seed production. For maximum seed production, grazing pressures should not be too heavy during August, September and October. It is during this time that tiller development occurs. After the first of November, grazingpressures may be increased and all growth should be removed by mid-January. Cattle should be removed from seed fields before March 15 in Southern Missouri and April 1 in North Missouri, otherwise, many of the potential seed heads will be grazed.
The seed of tall fescue shatters easily when ripe. Shattering due to harvest delays is common, usually caused by rains, unavailability of harvesting machines, or high winds; such shattering can easily reduce yields by 50% or more. Even under favorable conditions, extreme care and skill by the combine operator is necessary to prevent serious losses.
Fescue seed may be harvested by direct combining or windrowed and then combined. If the acreage of fescue seed to be harvested is small (can be combined in 1 or 2 days) and a combine is available without delay, then direct combining is a feasible method of harvesting. Combining should begin when 5-15 percent of the seeds are immature. Many of the late heads will still be immature at this time. Harvesting with more than 20 percent immature seed usually results in low yields, excessive seed moisture which will cause heating in storing, weak seed vigor and low germination.
If the amount of seed acreage is large or delays are expected in obtaining harvesting equipment, then the best method is windrowing and curing the seed in the windrow then using a combine with a pickup attachment. Fescue should be mowed at an earlier stage of seed head maturity when windrowed than when directly combined. Windrowing should be started when the straw in the head is yellowing. At this stage, an occasional seed will shatter from the earliest maturing heads in the field when the stem is tapped below the head.
The windrower should cut high enough to leave much of the grass stubble and the windrow placed on top of the stubble. Air will circulate through it and decrease drying time. The fescue should be combined as soon as the windrows are thoroughly dry, which can take 3 to 10 days depending on weather conditions.
The combine should be set according to the manufacturer's manual. Aggressive cylinder action is not necessary. Chaff should be examined for seed from time to time as harvest proceeds. The glumes, which do not contain seed, will often confuse an inexperienced operator and give the impression that seed is being blown out.
It is also helpful to consult seed dealers or buyers prior to harvest. They may suggest procedures about timing of harvest and handling that will help the producer to save more seed and improve seed quality as well.
(The original work of Howell N. Wheaton as a source of this material is gratefully acknowledged)
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REVISED: July 15, 2015