Cynodon spp.


Scientific name

1. Cynodon aethiopicus Clayton & J.R. Harlan
2. Cynodon nlemfuensis Vanderyst
3. Cynodon plectostachyus (K. Schum.) Pilg.

Subordinate taxa (C. nlemfuensis )
Cynodon nlemfuensis Vanderyst var. nlemfuensis
Cynodon nlemfuensis
Vanderyst var. robustus Clayton & J.R. Harlan

Because of the general similarity in appearance between the various giant types of Cynodon, there has been considerable confusion over the years in the taxonomic affiliation of many specimens.  It is suggested that all stargrasses identified as C. plectostachyus prior to 1970 were probably C. nlemfuensis.  We have therefore chosen to treat these major species on a single Fact Sheet in an attempt to address the confusion.  Epithets used in a particular publication should be viewed critically, since much of the available data actually relate to C. nlemfuensis or C. aethiopicus .

Synonyms

1. Cynodon plectostachyus auct. non (K. Schum.) Pilg.
2. Cynodon dactylon var. sarmentosus Parodi
    Cynodon parodii Caro & E.A. Sánchez
    Cynodon plectostachyus auct. non (K. Schum.) Pilg.
3. Leptochloa plectostachyus K. Schum.

Family/tribe

Family: Poaceae (alt. Gramineae) subfamily: Chloridoideae tribe: Cynodonteae .

Common names

1. Ethiopian dog's-tooth grass, star grass (English);  nakuru grass (Kenya);  reuse kweekgras (South Africa).
2. star grass, robust star grass, Rhodesian star grass;  african bermuda grass (English);  reuse kweekgras (South Africa);  giant star grass (Nigeria);  muguga star grass (Kenya);  african star grass (Australia);  estrela-africana (Portuguese - Brazil);  rumput bintang (Indonesia);  kolatay, rukut-dukut, galud-galud (Philippines);  ya-sata (Thailand).
3. giant star grass, star grass;  naivasha star grass (eastern Africa);  estrella (Spanish - South America);  bermuda mejorado, hawaiiano (Spanish - Costa Rica).

Morphological description

A largely robust, sometimes fine, stoloniferous (non-rhizomatous), deep-rooted group of perennials.  Stolons often woody, and culms to 100 cm tall, and 1-3 mm in diameter near the base.  Leaf blades flat, linear lanceolate, green to purplish-red, pubescent to almost glabrous, 3-30 cm long, 2-7 mm wide, minutely scabrous;  ligule a dense row of short hairs on a membranous rim 0.2-0.3 mm long.  Inflorescence a digitate or sub-digitate panicle, comprising 3-20 spreading, spike-like racemes 3-11 cm long, in 1-7 whorls.  Spikelets green, red or purple, 2-3 mm long, with 1 caryopsis/spikelet .  2.2-4 million spikelets/kg.
Details of differences can be seen in Table 1.

In C. nlemfuensis , var. nlemfuensis is finer and less robust than var. robusta (see key below):

Key to varieties of C. nlemfuensis :
Culms to about 40 cm tall, 1-1.5 mm diameter;  leaf blades 2-5 mm wide;  racemes 3-9, each 3.5-7 cm long. var. nlemfuensis
Culms to about 90 cm tall, 2-3 mm diameter;  leaf blades 5-6 mm wide;  racemes 6-13, each 6-11 mm long. var. robustus

Distribution

Native to:
Mostly from tropical east Africa, although extending into Angola (see Table 1 for detail).

Naturalised throughout the tropics and sub-tropics.  Occurs in disturbed areas in grassland, cattle paddocks and road verges, on moist alluvium.

Uses/applications

Can be grazed or harvested for hay or silage.  Larger types are suitable for cut-and-carry.  Useful live mulch and ground cover for weed control and soil conservation .

Ecology

Soil requirements

Grow on a wide range of soil types from sands to heavy clays, although best in moist, well-drained, lighter textured soils.  C. nlemfuensis is adapted to soils with a pH between about 4.5 and 8, but ideally between about 5.5 and 7, and is not as salt tolerant as C. dactylon C. plectostachyus is tolerant of alkaline soils and is always found in what appear to be alkaline areas in Kenya.  It is adapted to soils with pH 6.5-8.5, but gives best performance in the neutral to slightly alkaline range.

Moisture

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C. nlemfuensis grows in areas with an average annual rainfall between about 600 and 3,000 mm (commonly 800-1,200 mm), and appears to be more drought tolerant than C. aethiopicus that originates from areas of similar rainfallC. plectostachyus appears more drought-hardy than the others, growing down to 450 mm rainfall, but up to 4,000 mm (commonly 500-1,500 mm).  None tolerates prolonged flooding, but can withstand waterlogging for 2-3 days.  Very drought tolerant but produce little forage during periods of moisture stress.

Temperature

C. nlemfuensis occurs from about 15ºN to 15ºS, and from sea level to >2,300 m asl, representing a range in average annual temperature from about 20-27ºC.  However, in Florida, USA, it is not recommended north of a line between Brooksville and Orlando.  Although the average annual temperature in these cities is about 22ºC, the very low winter temperatures beyond the line can cause winter kill.  In Australia, var. nlemfuensis is naturalised in areas with average annual temperature down to 18ºC, suggesting the limitation lies either with the variety, or the freeze factor that is experienced in the USA but not in Australia.  C. aethiopicus extends over a similar native range to C. nlemfuensis , but C. plectostachyus appears limited to a more restricted range within the tropics than the others.

Light

All grow best in full sun or light shade, although some types, at least, seem adapted to moderate shade providing fertility is adequate.

Reproductive development

A more restricted flowering period than C. dactylon , apparently flowering in response to short days.

Defoliation

All are tolerant of heavy grazing although the finer types appear more grazing tolerant than the more robust types.  Under continuous heavy grazing or regular cutting in infertile soils, stands tends to succumb and the sward is opened to invasion by broadleaf weeds and C. dactylon .  If well fertilised, they grow vigorously, producing the best combination of yield and quality when grazed or cut every 4-5 weeks, which generally means maintaining a stubble height of 15-25 cm, and allowing the sward to reach 30-70 cm.  More rapid rotation of grazing animals (say every 1 or 2 weeks), can lead to higher liveweight gains, providing overall stocking rates and adequate stubble levels are maintained.

Fire

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Plants recover quickly after fire, and can even benefit through spittlebug and disease control by fire.

Agronomy

Establishment

Due to minimal seed set, these grasses are mostly propagated vegetatively, using either sprigs (above-ground stems) or stolons (runners) at a minimum of 1 t/ha on less than a 1 m grid.  The area should be free of C. dactylon .  Freshly harvested planting material is broadcast on clean cultivated soil and covered by discing 5-10 cm deep and heavily rolled.  With manual planting, stems are inserted into the soil to 75% of their length before compacting.  When placed in a moist, firm seedbed, nodes sprout in 5-10 days, and a solid stand can be achieved in 3 months after planting under good conditions.  Sprigs and newly established plants are susceptible to drought and should be kept moist.

Fertiliser

For optimum establishment and early growth, they should have an initial application of 40 kg/ha each of N, P, and K, with a follow-up application of 35-50 kg/ha N about 30 days later.  Under normal management, little fertiliser is required for survival, but stands are unproductive.  DM yields can be improved markedly by applications of nitrogen, with at least 10 kg/ha N applied monthly.  In hay production or cut-and-carry systems where plant material is removed, 50-100 kg/ha N should be applied 4-6 weeks before each cutting, and levels of other nutrients in the soil maintained or closely monitored.

Compatibility (with other species)

These are very vigorous grasses that, unmanaged, can overgrow associated legumes.  However, they are mostly not very shade tolerant, and can be shaded out by taller grasses and trees.

Companion species

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Grasses:  Usually not planted with other grasses.
Legumes:  Arachis pintoi , Centrosema molle (pubescens), Desmodium uncinatum , Lotononis bainesii , Stylosanthes guianensis , Trifolium repens.

Pests and diseases

None of these grasses is greatly affected by disease, particularly if managed to remain young and leafy.  The major diseases are rust, caused by Puccinia graminis and P. cynodonis, and Helminthosporium leaf-spot.  There are also records of leaf blight disease caused by Rhizoctonia solani during the rainy season, black choke on inflorescences and leaves caused by Ephelis sp., a smut caused by Ustilago cynodontis, and another spikelet disease caused by a Fusarium sp.
Nematodes isolated from these grasses include the stubby root (Trichodorus), spiral (Helicotylenchus), stealth (Hemicycliophora), ring (Hemicriconemoides), stunt (Tylenchorhynchus), awl (Dolichodorus), and lance (Hoplalaimus) nematodes.  Farmers need to be aware that build up of nematodes under stargrass can lead to severe consequences in subsequent nematode-susceptible vegetable and ornamental crops.
Fall armyworm (Spodoptera frugiperda) and spittlebug (Prosapia bicinata) are the major insect pests, along with strip grass looper caterpillar (Mocis latipes).

Ability to spread

Some types produce reasonable amounts of seed and have vigorous seedlings, so there is considerable potential for spread by seed.  However, most produce little or no seed and can only spread vegetatively.

Weed potential

All have fibrous, resilient stolons that survive ploughing, stands actually being improved by cultivation.  These grasses can therefore become weeds in cropping systems, although they are not as serious as C. dactylon .

Feeding value

Nutritive value

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Forage quality when harvested or grazed every 4-5 weeks is about the same for most star grasses.  Under good management with about a 4-week rotation, CP values are mostly of the order of 11-16% and IVOMD, 55-60%.  Quality can be improved to 18% CP and 68% IVOMD by reducing the rest period to 2 weeks, but persistence may suffer in some environments if the rest period is less than 3 weeks over an extended period.  Alternatively, if the rest period is increased to 7 weeks or more, CP levels can fall to 7-8% and IVOMD to 42-53%.  Stargrass is most nutritious when grazed every 4-5 weeks.  Phosphorus levels in the DM of between 0.1-0.4% and calcium from 0.2-0.5% have been recorded.  These are generally similar in 3.5-week regrowth of Digitaria eriantha (decumbens), Cynodon dactylon and C. nlemfuensis .  Digestibility of top growth killed by frost declines by 5-6 percentage units after 1 week, and 15-18 percentage unit after 4 weeks.

Palatability/acceptability

Although mostly very palatable when young, acceptability to cattle declines rapidly beyond about 5-week regrowth.  C. nlemfuensis is often preferred by cattle to the more robust C. aethiopicus .  Some varieties are not readily eaten at any stage.

Toxicity

Both C. aethiopicus and C. nlemfuensis have the potential to produce high levels of prussic acid (HCN) any time during the growing season, particularly when heavily fertilised with nitrogen.  Levels of up to 150 ppm HCN have been measured in C. nlemfuensis and up to 250 ppm in C. aethiopicus .  These decline after about 4 weeks.  However, confirmed cases of prussic acid poisoning are not common.  While reports of high levels of HCN in C. plectostachyus exist, these may well result from mistaken identification of the species in question, and actually refer to C. nlemfuensis .

Production potential

Dry matter

Yields vary greatly with time of year, moisture availability, defoliation management, and nitrogen fertility.  In the subtropics, C. aethiopicus , C. nlemfuensis and C. plectostachyus can produce monthly summer yields of the order of 1,000-2,000 kg/ha, 1,600-2,000 kg/ha, and about 1,300 kg/ha/month respectively, compared with 165-500 kg/ha, 400-1,000 kg/ha and 300-1,100 kg/ha during the cool winter months.  Annual dry matter yields vary from about 5 t/ha in low input systems to 10-15 t/ha with good management, and up to 25 t/ha with irrigation and high N fertilisation.

Animal production

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Average liveweight gains of 700-800 kg/ha from 225 kg steers grazing at a stocking rate of 8 beasts/ha can be achieved over a 200-day warm season from well-managed pastures.  However, 1,000-1,500 kg/ha are also possible.

Genetics/breeding

Ploidy levels are shown in Table 1.  Evidence suggests that some types, at least of C. aethiopicus , are apomictic, while C. nlemfuensis may be outcrossing.  Although these grasses all appear similar, DNA comparison indicates strongest species similarities were between C. aethiopicus and C. arcuatus, C. plectostachyus and C. transvaalensis, and C. nlemfuensis and C. incompletus, and little variation within C. aethiopicus .

Seed production

Some types of C. aethiopicus and C. plectostachyus are capable of significant seed production, although experience in Florida suggests varieties of C. aethiopicus there produce little or no seed.  Most workers agree that C. nlemfuensis prduces very low amounts of seed.

Herbicide effects

Broadleaf weeds can be controlled using a mixture of dicamba and 2,4-D.  For harder-to-kill pasture weeds triclopyr may be effective.  Cynodon spp. are generally fairly tolerant of glyphosate at normal rates, but appear susceptible to haloxyfop.

Strengths

  • Rapid establishment from vegetative cuttings.
  • Persistent when properly managed.
  • Drought tolerant.
  • Some types make good cool season growth with adequate moisture and fertility.
  • Palatable and high quality forage when harvested or grazed regularly.
  • Good LWG per animal and per hectare.
  • Hay cures rapidly under favourable conditions.

Limitations

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  • No seed available.
  • Low productivity during dry periods.
  • Top growth killed by frost.
  • Requires higher fertility than Paspalum notatum , Hemarthria altissima and Digitaria eriantha (pangola).
  • Forage quality drops rapidly after 5 weeks of regrowth and following heavy frost.
  • Acceptability to cattle declines rapidly with time.
  • Some types produce high HCN.

Other comments

  

Selected references

Bogdan, A.V. (1977) Tropical Pasture and Fodder Plants (Grasses and Legumes). pp. 98-103. (Longman: London and New York).
de Wet, J.M.J. and Harlan, J.R. (1970) Biosystematics of Cynodon L. C. Rich. (Gramineae). Taxon, 19, 565-569.
Hanna, W.W. Cynodon nlemfuensis Vanderyst. In: 't Mannetje, L. and Jones, R.M. (eds) Plant Resources of South-East Asia No. 4. Forages. pp. 102-104. (Pudoc Scientific Publishers, Wageningen, the Netherlands).
Harlan, J.R., de Wet, J.M.J., Huffine, W.W. and Deakin J.R. (1970) A guide to the species of Cynodon (Gramineae). Oklahoma Agricultural Experiment Station Bulletin B-673.
Harlan, J.R., de Wet, J.M.J. and Rawal, K.M. (1970) Geographic distribution of the species of Cynodon L. C.Rich (Gramineae). East African Agricultural and Forestry Journal, 36, 220-226.
Hodges, E.M., Boyd, F.T., Dunavin, L.S., Kretschmer, A.E. Jr., Mislevy, P. and Stanley, R.L. Jr. (1975) 'McCaleb' Stargrass.  Agricultural Experiment Station, IFAS, University of Florida. Circular S-231.
Mislevy, P. (1989) Florona Stargrass.  Agricultural Experiment Station, IFAS, University of Florida. Circular S-362.

Internet links

Cultivars

Cultivars

Country/date released

Details

C. nlemfuensis
'Florico'
(Puerto Rico PI 2341; PI 562690)
Florida, USA (1988) Originally from Kenya, evaluated in Puerto Rico.  Leaves and leaf sheaths hairy.  Differentiated from 'Ona' and 'McCaleb' by its hairiness and dark green-purplish colour.  Adapted to soils that are saturated but not flooded for long periods of time.  High nutritive value if managed correctly.  Good carrying capacity and average daily gain, and higher IVOMD and better persistence than 'Ona'.  Tends to average about 2-3 percentage units higher IVOMD than 'Florona', 'Ona', or 'McCaleb' stargrass.  Potential to produce high levels of HCN.
'Florona'
(PI 562691)
Florida, USA (1988) Naturalised type of unknown origin.  Leaves and leaf sheaths glabrous except for few hairs on upper surface of leaf.  Adapted to soils that are saturated but not flooded for long periods of time.  Forms a moderately open sod with clumps of erect stems giving a bunch effect.  Higher yielding than 'Ona' and 'Florico' but slightly lower digestibility.  Potential to produce high levels of HCN.
'IB-8' ('Ibadan 8') Southern Nigeria Originally from Tanzania.  Higher yielding but nearly 50% lower intake than 'IB-1', the local variety.
'Ona'
(PI 224566)
Florida, USA (1979) Institutional collection from Zimbabwe.  Adapted to soils that are saturated but not flooded for long periods of time.  Higher yielding during the cool season than Paspalum notatum or Digitaria eriantha (pangola).  Good disease resistance and insect tolerance and an acceptable nutrient content.  Potential to produce high levels of HCN.  While some 'Ona' still exists, much has been replaced by 'Florona' and 'Florico'.
'Okeechobee' Florida, USA Origin unknown.  A contaminant in stands of C. dactylon cv Callie;  more persistent than 'Callie'.  Dry matter yields similar to 'Florona', but slightly lower CP levels and slightly higher IVOMD under similar management.
C. aethiopicus
'Henderson No. 2'
(PI 617094)
Zimbabwe Origin unknown.  Sometimes listed as C. nlemfuensis .  Early elite variety, distributed to other countries including Malawi and USA.
'McCaleb'
(PI 224152)
Florida, USA (1975) Institutional collection from Johannesburg, South Africa.  Adapted to soils that are saturated but not flooded for long periods of time.  Establishes rapidly with high forage production under high fertilisation.  Standard for subsequent releases. Replaced by C. nlemfuensis varieties, which are more persistent.
C. plectostachyus
None released to date.      

Promising accessions

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Promising accessions

Country

Details

None reported.      

Table 1.  Distinguishing characteristics of giant Cynodon spp.
Species aethiopicus nlemfuensis plectostachyus
Origin Democratic Republic of Congo (Zaire)
Ethiopia
Kenya
Malawi
Mozambique (north-west)
Rwanda
Sudan (south-east)
Tanzania
Uganda
Zambia
Zimbabwe
Angola
Democratic Republic of Congo (Zaire)
Ethiopia
Kenya
Malawi
Sudan (south-east)
Tanzania
Uganda
Zambia
Zimbabwe
Ethiopia
Kenya
Tanzania
Uganda
Ploidy 2n = 18, 36 mostly 2n = 18 (rarely 36) 2n = 18
Stoloniferous/rhizomatous stoloniferous stoloniferous stoloniferous
Stolon character appressed to ground, woody, coarse appressed to ground, not woody thick, arching
Stem length 40-100 cm 70-100 cm 30-90 cm
Leaf length to 25 cm to 16 cm 10-30 cm
Leaf width to 7 mm 5-6 mm 4-7 mm
Leaf character no information stiff, glaucous , ± hair soft and hairy
Flowering time January to June (South africa) January to March (South Africa) no information
Raceme whorls 2-5 (rarely 1) 1 or 2 2-7
Raceme number 5-17 3-13 7-20
Raceme length 4-8 cm 6-11 cm 3-7 cm
Raceme character stiff, red or purple slender or flexuous, green or pigmented rigid, curling upward at maturity
Spikelet length 2.5-3 mm 2-3 mm 2.5-3 mm
Glumes keel of lemma glabrous or with sparse hairs glumes narrow lanceolate, the upper, 1/2-3/4 length of spikeletlemma silky pubescent to softly ciliate, palea glabrous . small glumes (triangular scales), rarely as long as 1/4-? of spikelet length;  lower 0.2-0.3 mm, upper 0.4-0.6 mm.
Seed production good poor good
Plant vigour (competitiveness) > C. nlemfuensis intermediate < C. nlemfuensis
Note:  All distinguished from C dactylon by absence of rhizomes.