Arizona cottontop (Digitaria californica)

Datasheet

Description

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Arizona cottontop (Digitaria californica), habit, Prescott, Arizona

Arizona cottontop (Digitaria californica), spikelets, Prescott, Arizona

Common names

Arizona cottontop, cottontop [English]; punta blanca [Spanish]

Species

Digitaria californica (Benth.) Henrard [Poaceae]

Synonyms

Panicum californicum Benth., Trichachne californica (Benth) Chase

Related feed(s)

Description

Arizona cottontop (Digitaria californica (Benth.) Henrard) is a perennial, warm-season bunchgrass. It has an extensive root system (Walsh, 1993). The stems are slender, 30-100 cm high. They are swollen, scaly and hairy at the base. The leaves are flat, narrow (25 mm broad) and vary from 8 to 25 cm in length. The leaf can be inserted high on the stem, often reaching the inflorescences (Bogdan, 1977). Inflorescences are terminal, 5-20 cm long panicles. The spikelets are borne in pairs on the rachis. Their glumes and lemna are covered with long white hairs giving a silky cottony appearance, hence the name cottontop (Magee, 2002).

Digitaria californica is mainly used as pasture for cattle, horses and sometimes sheep and goats (Magee, 2002). It is used for environmental services (Magee, 2002; Walsh, 1993).

Distribution

Digitaria californica is a warm-season, fast growing grass. It is native to the southern states of the USA and to Central America. It is now widespread southward down to Argentina, where it is a major component of the Pampas grasslands. Digitaria californica occurs widely, including on "mesas", rocky hills, broad alluvial plains and river bottoms. It is found from sea level up to 1900 m altitude in arid and semi-arid grasslands (Walsh, 1993; Bogdan, 1977).

Digitaria californica is frost tolerant down to 2-3°C. It withstands pronounced drought and can adapt to different rainfall regimes. It can grow on a wide range of soils but does better on clay, sand and sandy loam than on shallow stony or stoney soils. It can grow on low-fertility desert soils but may show some chlorosis in such conditions. It can survive fire and regrow as the growing points are at ground level or below ground level. Fire may enhance the growth of the plant (Walsh, 1993; Bogdan, 1977).

Forage management

Digitaria californica seeds easily. Its seeds remain viable for 14 to 25 years and it can thus be sown or vegetatively propagated from basal buds. Once established, the stand is drought-hardy and long-lived. Culms survive 3 to 15 years. Seedlings need fairly long rainy period to establish: wet years are good for stand regrowth from seeds. Digitaria californica is much valued because it can always benefit from rainy periods to initiate new shoots and regrow when the moment is favourable, even after drought (Walsh, 1993; Cable, 1982). In very infertile desert soils, it is more productive when grown under mesquite (Walsh, 1993).

Digitaria californica cures well and gives good winter forage as the stems remain green. It can be grazed over long periods as grazing promotes shoot development, increasing grass productivity (Walsh, 1993). However, while promoting regrowth, defoliation results in a decline of below-ground biomass (by 50%). When sown with another grass such Lehmann grass (Eragrostis lehmanniana), the lesser resistance to grazing of Digitaria californica may lead to a reduction of its population (Cox et al., 1992). Digitaria californica is highly palatable and is thus susceptible to overgrazing. It is recommended to reduce grazing during the growing period 2 years out of 3 (Walsh, 1993).

Nutritional aspects

Nutritional attributes

Information about the nutritional value of Digitaria californica is scarce. Data reported in the Argentine Pampas show a poor nutritive value, similar to that of other grasses in the same region: 7-13% DM of crude protein and in vitro DM digestibility of about 37-50% (Cerqueira et al., 2004; Cozzarin et al., 2006).

Ruminants

Digitaria californica is one of the main components of the Argentine natural grasslands (Cozzarin et al., 2006). It is relished by cattle and is preferred as stocking rate increases (Guevara et al., 1996). Its utilization factor (percent utilization of available forage) increased by 10% when cattle stocking rate went from 18 ha/head/year to 15 ha/head/year (Orionte et al., 1980). In the arid piedmont of Argentina, grazing goats preferred Digitaria californica to browse species (Grünwaldt et al., 1994). Digitaria californica can sustain the nutritional requirements of breeding cows if calving date is correctly planned (Silva Colomer et al., 1991).

Pigs

No information found (2013).

Rabbits

Digitaria californica could be considered as a suitable forage for rabbit feeding though no direct experiments have been reported in the literature (April 2013). This supposition is based on a 4-year study that showed selective grazing of Digitaria californica by black-tailed jackrabbits (Lepus californicus) in the Texas High Plains: Digitaria californica represented 3.2% of faeces DM while its relative frequency in the habitat was only 0.9% (Flinders et al., 1977).

Nutritional tables

Tables of chemical composition and nutritional value

Arizona cottontop (Digitaria californica), aerial part, fresh

Avg: average or predicted value; SD: standard deviation; Min: minimum value; Max: maximum value; Nb: number of values (samples) used