Colonial Bent, Agrostis capillaris, bent, colonial bent, browntop

Astoria bent, black couch, brown bent grass, brown top, brown top bent grass, burden’s grass, colonial bent, common bent grass, common bent grass, dew grass, English bent, furze top, New Zealand bent grass, Prince Edward Island bent grass, Rhode Island bent, Rhode Island bent grass, Waipu bent, brown-top grass, colonial bent grass and common bent are some of the common popular names of the plant. The name Agrostis comes from the Greek word meaning forage plant, agros meaning a field. Although this species is used on golf courses, providing some of the best ball playing surfaces in the world, it also produces a remarkable visual appearance when maintained properly. It offers an excellent home lawn but is not tolerant of heavy use.

Colonial Bent Facts

Plant Description

Colonial bent or common bent is a low-growing, matted, rhizomatous and stoloniferous perennial grass that normally grows about 20-25 cm or 100 cm tall. The plant is found growing in ruderal, disturbed areas, heathland, woodland, scrub, sand dune habitats, heathy woodlands, lowland grasslands, grassy woodlands, dry and damp sclerophyll forests, riparian vegetation and alpine and sub-alpine vegetation, montane peatlands, swamps, urban areas, dry coastal vegetation, moist grasslands, open meadows, agricultural areas, roadsides, and invading disturbed areas and freshwater wetlands.

The plant has a preference for poorly drained, fine to medium textured soils of pH 6.5 to 7.3 with a moderate level of organic matter. It is tolerant of temperature extremes. Roots have rhizomes and occasionally stolons. Stems are spreading and grow to 80 cm long. The plant spreads predominantly by underground rhizomes. The entire plant is hairless. The plant has a very fine texture and like most bent grasses grows very dense. Colonial bent is fairly easy to grow from seeds and fertilization of the lawn is not as intense. This grass also takes longer to establish than creeping bent. However, it does not require intense maintenance.

Leaves

Stems (stolons) are decumbent (creeping) and slender and produce long narrow leaves. Leaf-blades are smooth on the upper surface and ridged on the underside, 1 to 3 mm wide and bluish-green in appearance. The ligule is long, membranous, finely toothed or entire and rounded, auricles are absent.

Flower

The species is characterized by single flowered spikelet in a compact panicle. The panicle in flower is purple to bronze in appearance. The flowering panicles appear from June to August. The panicle persists in winter after the seeds have been shed.

The plant propagates by way of highly abundant seeds and vegetatively by rhizomes and stolons. The large proportion of A. capillaris clones and low proportion of seedlings in populations suggests that much of its reproduction is vegetative. Flowers are wind pollinated, but are also spread by water, humans and vertebrates.

Fruit

Seed heads are usually 15 cm long with spreading branches with tiny seeds. Seeds of Colonial bent are too small to be recognized without magnification. Seeds are ovate, less than 1 mm long, usually awn less with an occasional short, straight awn and silvery in appearance. Seed is set from August to October in the northern hemisphere. Seeds may persist for 5 years or more.

Other Facts

• It is used in garden lawn mixtures and in particular for tennis courts, high-grade lawns, golf course fairways and erosion control.
• It is a food source for herbivores, including rabbits.
• It is a valuable agronomic species because of their ability to produce fodder as well as provide food for grazing animals.

Prevention and Control

Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authorities should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product’s label.

Cultural Control and Sanitary Measures

A. capillaris is highly adapted to grazing and tolerant of burning, so neither of these mechanisms can be used to control the species and can, in fact, result in increased abundance. In cultivated areas, where A. capillaris can become a weed, short rotations with root crops may help reduce this species.

Physical/Mechanical Control

For Agrostis species in general, conventional control including physical removal is considered difficult or not feasible even when they exert a large negative impact on native biodiversity. However, for A. capillaries, mechanical removal by hand pulling, plowing, grubbing and harrowing can reduce abundance. It can also prevent seeding when applied in spring or early summer before the seed set. Manual removal is labor intensive and the remaining pieces of broken stolons can be re-establish.

Biological Control

There are no known biological control agents available for A. capillaris and the value of the species worldwide as a commercial fodder and lawn grass may preclude any attempts at biological control.

Chemical Control

The graminicide cycloxydim has been used to effectively control A. capillaris in forest tree establishment situations (Clay et al., 2006). A. capillaris is also susceptible to the herbicides dalapon, hexazinone and sethoxydim, the last giving a 100% mean control rate, while glyphosate applied before emergence reduces growth rate. The introduction of glyphosate resistance into A. capillaris by genetic engineering may have implications for the species’ invasiveness, spread, and control. Herbicides should only be used with extreme caution, and under expert advice, insensitive Garry oak ecosystems.

Other Techniques

Prescribed burning is not an effective management method for colonial bentgrass as a study in Oregon found an abundance of the species to be ten-fold in burned versus unburned areas. Colonial bentgrass can also not be managed by cutting or grazing. Due to its low stature, its relative leaf loss is minimal in comparison to other grass species, and it is thus able to maintain its competitive advantage. Grazing on colonial bent grass in cultivated plots was even found to increase the abundance of the species.

Preventative Measures

Soil disturbance and the use of fertilizers should be avoided in natural areas. Equipment, clothing and animals should be checked and cleared for seeds when leaving an infested area. Encourage plant nurseries, gardeners and farmers to stock and use native or non-invasive species, and to avoid using non-native grasses such as colonial bentgrass.

References