Broomsedge ( Andropogon virginicus ) is one of the most frequently-encountered noncultivated plants in Alabama . Despite the taxonomic implications of its common name, this plant is a grass , rather than a sedge . It is widely adapted and commonly present in non-cropland areas and pastures throughout the Southeast.

Broomsedge is native to our region, and its name arose from the once-common practice of collecting mature plants, tying them into a bundle, and then using the bundle as a broom. Because this species is so widespread and visible in the Southeast, it is easily recognized and widely known to a high percentage of people, including many urban dwellers.

Although it is no longer used to make brooms, broomsedge still serves some useful purposes. It helps reduce erosion in abandoned fields and waste places, it helps provide cover for wildlife, and the golden color of mature broomsedge brightens many areas, which would otherwise be drab.

Unfortunately, broomsedge is an undesirable species in pastures. It has relatively little nutritional value for livestock, but it takes nutrients, water, sunlight, and space that could otherwise be used by more desirable plants to produce good quality forage. A heavy infestation of broomsedge is often considered to be an indicator of a poor pasture.

Reasons for Broomsedge Encroachment

It is commonly believed that any area infested with broom-sedge is low in fertility or has a low soil pH. While this often is the case, it is not necessarily so. Low soil pH and/or low soil fertility often play an important role in allowing broomsedge to become established , but correcting these conditions may not immediately eliminate a population of broomsedge plants. In addition, the extent of defoliation greatly impacts on broomsedge establishment and persistence as will be explained later.

Broomsedge is actually not highly competitive, and this is especially true for seedlings. When soil fertility and pH levels are relatively high and there are well-adapted, vigorous forage plants covering most of the surface area in a pasture, it is difficult for young broomsedge plants to become established. Once they do become well-established, their ability to compete greatly increases.

It is possible for broomsedge to invade a pasture even when soil pH and fertility are near optimum. An example of this is when a forage species is planted that is not well-adapted to the site, resulting in a weak stand of forage plants. Broomsedge might be considered an opportunistic" plant; it doesn't force its way into pastures, it merely takes advantage of opportunities!

As mentioned earlier, defoliation (especially grazing management) profoundly influences the ability of broomsedge to become established and survive. Broomsedge becomes extremely unpalatable as the forage becomes more mature. Therefore, though livestock will consume the young growth, they will refuse it under almost any circumstance once it becomes mature.

This characteristic of broomsedge allows it to become established most easily in situations where pastures are undergrazed in the spring and early summer but overgrazed in mid- to late summer. If pastures are undergrazed in the spring, young broomsedge plants (which would be weakened by grazing if the stocking rate was higher) are allowed to reach the stage of growth at which they become highly unpalatable.

In summer, drought and/or hot weather often slows pasture growth (this is particularly true with cool season perennial grasses such as tall fescue) and livestock begin to consume the accumulated forage growth. However, at this point livestock refuse the broomsedge and heavily graze the improved forage species. This has the effect of reducing or eliminating the competitive advantage that improved forage species otherwise have .

Controlling Broomsedge

In controlling broomsedge , the old adage, "an ounce of prevention is worth a pound of cure" applies. It is easier to keep broomsedge out of a pasture than it is to get it out, but elimination of this weedy pest can be accomplished easily enough over time with persistent application of the right management.

The selection and use of well-adapted, vigorous forage species and varieties are certainly helpful in keeping broomsedge from becoming established. In addition, soil testing on a regular basis followed by the application of recommended fertilizer and lime will, in most cases, keep broomsedge out.

The "spring undergrazing -summer overgrazing" situation described in earlier paragraphs should be avoided. This can be done either by adjusting stocking rates as necessary or by clipping pastures periodically. To the extent that pastures are grazed or clipped without exceeding the tolerance limits of the particular forages being grown, the more difficult it is for broomsedge plants to be competitive.

Broomsedge is a perennial, which means that established plants will normally "come back from the roots" year after year. This is especially true if the low soil fertility levels, low soil pH, and/or the defoliation schedule which allowed them to become established continue. Eliminating these conditions will eventually eliminate the broomsedge , but it takes time to do so because broomsedge is more competitive once it has a good root system established.

In some instances, doing nothing other than liming and fertilizing a pasture well for several years will reduce a broom-sedge population, but this may be slow process. This will usually stop the spread of this weedy grass, but it may take a long time to significantly reduce the broomsedge population.

In cases in which there is a thick stand of broomsedge and only a low population of desirable forage plants, it may be desirable to renovate a pasture. This would normally require killing the existing broomsedge either with non-selective herbicides or with tillage, then reseeding or resprigging desirable forage species in the area.

If this is accompanied by fertilization and liming according to soil test recommendations and by frequent defoliation, any broomsedge plants which escape the tillage and herbicides or which come from seed present in the soil will be at a great competitive disadvantage. At present there are no labeled herbicides that will selectively remove broomsedge without harming desirable forage plants.

Historical Precedent

An old University of Tennessee Agricultural Experiment Station circular titled, "Control of Broom Sedge" long ago revealed that management can eliminate broomsedge . This publication, written by L.R. Neel and published in 1936, reported the results of several experiments. These studies dated back as far as 1927 and were aimed at learning more about broomsedge and how to control it.

The tests discussed were conducted at the Middle Tennessee Experiment Station and were designed to evaluate the effects, which the following treatments would have on broomsedge stands:

(1) application of commercial nitrogen fertilizer or livestock manure; (2) defoliation; and (3) competing forage crops. Because the soils at this location were known to contain good levels of phosphorus and potassium, application of these nutrient elements was not included as experimental treatments.

Results were dramatic. Application of 200 pounds/acre of nitrate of soda or 150 pounds/acre of ammonium sulfate, together with grazing and two or three clippings per year reduced broomsedge stands from 90% ground cover to less than 5% in four years. These same treatments resulted in good forage stands in areas where forage crops had been seeded.

In a companion test, the lifespan of broomsedge was evaluated by space planting broomsedge plants with no treatments imposed except that half of the plants were clipped regularly.

The result was that half of the plants had died out by the end of 3 years, nine-tenths were gone by the end of 6 years, and all had died by the end of the 7th year. The rate of death was more rapid where regular defoliation had occurred. This implies that in areas where broomsedge persists over a long period of time, reseeding as well as perenniation is occurring.

The experimental results were corroborated by observations of the effects of grazing and fertilization on some 400 acres of permanent pasture on the Middle Tennessee Experiment Station. It was noted that pastures which were kept grazed closely in spring and early summer for several straight years had very little broomsedge remaining, while in other pastures where lax grazing had occurred, populations increased despite good fertilization.

Conclusion

The key to controlling broomsedge is to ensure that desirable forage plants have a competitive advantage. This includes maintaining soil pH and soil fertility levels and making certain that the defoliation regime does not favor broomsedge plants.

One of these steps alone may not eliminate a thick stand of established broomsedge , or do so only very slowly. However, tipping the competitive edge toward forage species and away from

broomsedge will be effective in the long run. Planting forage crop seed may also be necessary if there are not enough forage plants present to recover a good stand.