Kikuyu grass

Pennisetum clandestinum

Family: Poaceae.

Names:

Pennisetum is from the Latin penna meaning feather and seta meaning bristle and refers to the feather like bristles on the flowers, of some species in this genus.
Clandestinum refers to the clandestine or hidden seed heads.
Kikuyu grass.

Summary:

A creeping, aggressive, course, perennial lawn grass spreading by runners (stolons and rhizomes) and with seed heads that are hidden within the leaf structure and only showing long, white, thread like stamens at flowering in summer. Native to eastern Africa, it is a common lawn grass and pasture but also a weed of disturbed land near settlements or pasture.

Description:

Cotyledons:

One.

Leaves:

Bright green. Emerging leaf folded flat in the bud.
Blade - Parallel sided, 10-300 mm long x 2.5-7 mm wide, tapers to a narrow pointed tip. Initially tightly folded but flattening with age. Soft and smooth except for rough edges and midrib. Mid vein conspicuous. Hairless or with wart based hairs on the upper and lower surfaces. Gradually merge into sheath.
Ligule - Hairy ring, 1-2 mm long x up to 6 mm wide.
Auricles - None.
Sheath - Closely overlapping, almost membranous, 10-20 mm long, pale green when young and turn brown with age, merge into the blade. Usually hairy especially on the edges.

Stems:

Creeping, closely matting, many branched, slender to stout stolons, up to 10000 mm long. Clumps can be up to 2000 mm deep but usually less than 500 mm deep. Roots at the hairless nodes. Branches often short and erect if not mown or grazed. Long, aggressive, underground rhizomes.
Flower stem - Culms 70-150 mm long in late spring to summer and enclosed within the upper leaf sheaths.

Flower head:

On short shoots in the axils of leaf sheaths. A cluster of 1-4, usually 3, spikelets, usually enclosed in top leaf sheaths. Each spikelet is subtended by about 5 and up to 15, fine, roughened, bristles of differing lengths up to 15 mm long.

Flowers:

Spikelets - Narrowly egg shaped, 10-20 mm long x 2-3 mm wide, white underneath, green on top, 2 flowered. End one may have short stalk, others have almost no stalk. Hairless.
Florets - Lower one empty. Upper one appears bisexual but either functionally male or female. Stamens and styles protrude from the sheath at flowering.
Glumes - Lower one tiny or absent, translucent, no ribs. Upper one egg shaped, to 2 mm long, translucent, usually no ribs.
Palea - Absent on lower floret. On the upper floret it is narrowly egg shaped, very thin, 2-4 ribbed and long with a tapering pointed tip.
Lemma - Lower one narrowly egg shaped, tapering, as long as spikelet, 10-20 mm, thin and membranous, 8-13 ribbed. Upper one similar but slightly shorter.
Stamens - 20-40 mm long and protrude from the sheath at flowering as silvery threads.
Anthers -

Fruit:

Brown, 2 mm long x 1 mm wide.

Seeds:

Very small.

Roots:

Fibrous roots develop at each node in contact with the soil. Many, stout, round, 5-10 mm diameter rhizomes covered with bracts and white pointed tips. Rhizome may reach a depth of 500 mm.

Key Characters:

Emerging leaf folded flat in the bud.
The ligule is a ring of hairs, 1-2 mm long x up to 6 mm wide.
No auricles.
Inflorescence a cluster of 2-4 spikelets usually enclosed in the upper leaf sheaths.

Biology:

Life cycle:

Perennial. Winter dormant. Flowers October to March.

Physiology:

Waterlogging tolerant, stems and roots contain air channels.
Moderately frost tolerant.
Grazing and trampling tolerant.
Reasonably tolerant of sand blast.
Winter dormant.
More cold tolerant than Paspalum.

Reproduction:

By seed and stem fragments.

Flowering times:

Late spring to autumn in western NSW.
Summer in SA.
October to March in Perth.
Summer in WA.

Seed Biology and Germination:

Requires temperatures above 15-20oC for germination.
Sets little or no seed unless it is mown or grazed.

Vegetative Propagules:

Stem fragments.

Hybrids:

A number of ecotypes exist.
Cultivar Whittet is suited to poorer soils and irrigated pastures and is resistant to kikuyu yellows.
Cultivar Breakwell is more densely branched and prostrate and is useful for soil stabilisation pastures and is resistant to kikuyu yellows.

Allelopathy:

Population Dynamics and Dispersal:

Spread mainly by intentional planting.
Varieties that form seed are now commonly grown. Previously most varieties only propagated vegetatively and stolons had to transplanted to invade new areas.
Locally it can spread several metres per year by stolon and rhizome growth.
Newer varieties are spread by seed and in stock manure.

Origin and History:

Africa. Uplands of East Africa.

Distribution:

ACT, NSW, NT, QLD, SA, TAS, VIC, WA.
New Zealand.
Limited by frost (561).

Courtesy Australia's Virtual Herbarium.

Habitats:

Moist and wet areas.

Climate:

Temperate. Mediterranean.

Soil:

Prefers fertile loamy soils but also abundant on sandy soils.
Tends not to persist on soils subject to severe drying or cracking.
Grows on a wide range of soil types.

Plant Associations:

Significance:

Beneficial:

Spring, summer and autumn fodder grass in coastal areas where frosts aren't too severe.
Unpalatable if allowed to go rank.
Used as a lawn grass.
Used on race courses because of its quick recovery from hoof damage.
Planted on irrigation channels to reduce erosion.
Used as a soil stabiliser in sandy areas.

Detrimental:

Weed of vegetables, gardens, orchards, cultivation, fine lawns, rotation crops, perennial crops, grass lands, swamps, wetlands, dunes, riparian, bushland, and disturbed areas.
Impedes water flows in drains.
Fire hazard and it is difficult to extinguish old stands.
It forms dense mats and smothers most other species and prevents recruitment of overstorey species.
It is listed as one of the "Worlds worst weeds of cropping" and as a "Garden thug".

Toxicity:

Usually safe to graze. It can contain potentially toxic levels of nitrates in lush growth under high nitrogen and good growing conditions. For example ungrazed stands in stockyards.
Contains oxalates. Horses and cattle are more susceptible than sheep.
It contains allergenic substances that affect some people and asthma sufferers.

Legislation:

None.

Management and Control:

Mainly vegetative spread, but new agricultural varieties set viable seed. Once established it is difficult to control. Seed set is greater after close mowing or grazing.
Very heavy grazing will control it. It is tolerant to mowing. Clean mowing equipment to reduce spread to clean areas especially from late spring to autumn.
In cropping areas, Kikuyu can usually be reduced to insignificant levels by using glyphosate for spray topping, summer weed control and pre plant weed control.
A typical program would be heavy autumn grazing followed by heavy grazing in late winter to spring with stock being removed when the annual grasses start to elongate in spring. When the heads of annual grasses just start to emerge Spraytop with 800 mL/ha glyphosate(450g/L) followed by 800 mL/ha 4 weeks later. If summer weeds emerge then spray with glyphosate at a rate appropriate for the weeds. In autumn spray annual weeds when they have reached the 2 leaf stage with about 2 L/ha glyphosate(450g/L). Rates should be adjusted so that a total of 3-4 L/ha glyphosate is applied over the 2-4 sprays. This will give results similar to applying 6 L/ha as a single application. Cultivation, 2-10 days after spraying with a scarifier or using a tyned full cut seeder to plant the crop will provide improved control compared to minimum tillage planting.
Don't plant close to bushland.
Don't dispose of garden waste and lawn clippings in bushland.

Thresholds:

Eradication strategies:

Manual control is usually very difficult.
It can often be eradicated in a single season with herbicides. Pay special attention to last few runners as these will quickly form a new infestation if not controlled.
Spray with 4 L/ha of glyphosate(450g/L) plus 0.25% Pulse® Penetrant (or 80 mL of glyphosate(450g/L) plus 25 mL of Pulse® Penetrant per 10 L of water for hand sprays) in September, December and March each year. This will kill most other vegetation but can be used around the base of established trees with dry thick bark.
In broadleaf gardens and crops spraying every 8 weeks from September to April with 800 mL/ha Verdict®520 or 4 L/ha quizalofop(100g/L) or 6.4 L/ha Fusilade®Forte plus 1% spray oil. Use 16 mL Verdict®520 or 80 mL quizalofop(100g/L) or 125 mL Fusilade®Forte plus 100 mL of spray oil per 10 L water for hand sprays.
Painting runners or crowns with 1 L glyphosate in 2 L water is useful in sensitive areas.
Most other grass selective herbicides are also effective.
It is difficult to remove manually as all the surface runners and underground rhizomes must be removed without breakage.
Solarisation by covering with plastic sheets for 8-12 weeks in summer provides reasonable control. Treat regrowth after sheet removal with glyphosate.
Burning alone provides little control, however it is useful to reduce the thatch and provide vigorous regrowth that is more sensitive to herbicides. It often reduces damage to companion plant by reducing the amount of leaf that is exposed to herbicides.
In bushland areas, encourage scrub and tree species to reduce light levels.
Mowing is ineffective. Cultivation is usually ineffective unless repeated regularly.
Avoid dumping garden refuse containing these grasses in areas where they may establish.

Herbicide resistance:

Biological Control:

Related plants:

African Feather grass (Pennisetum macrourum)
Elephant grass (Pennisetum purpureum)
Feathertop. (Pennisetum villosum)
Fountain grass (Pennisetum setaceum)
Mission grass (Pennisetum polystachion)
Pearl Millet (Pennisetum glaucum)
Swamp Foxtail (Pennisetum alopecuroides)
Pennisetum pedicellatum

Plants of similar appearance:

Grasses.

References:

Auld, B.A. and Medd R.W. (1992). Weeds. An illustrated botanical guide to the weeds of Australia. (Inkata Press, Melbourne). P53. Photo.

Black, J.M. (1978). Flora of South Australia. (Government Printer, Adelaide, South Australia). P229.

Blood, K. (2001). Environmental weeds: a field guide for SE Australia. (CH Jerram & Associates, Australia). P217. Photo.

Ciba Geigy (1980) Grass Weeds 1. CIBA GEIGY Ltd, Basle, Switzerland. P112. Diagrams.

Cunningham, G.M., Mulham, W.E., Milthorpe, P.L. and Leigh, J.H. (1992). Plants of Western New South Wales. (Inkata Press, Melbourne). P128.

Everist, S.L. (1974). Poisonous Plants of Australia. (Angus and Robertson, Sydney). P338.

Hussey, B.M.J., Keighery, G.J., Cousens, R.D., Dodd, J. and Lloyd, S.G. (1997). Western Weeds. A guide to the weeds of Western Australia. (Plant Protection Society of Western Australia, Perth, Western Australia). P62. Photo.

Lamp, C. and Collet, F. (1990). A Field Guide to Weeds in Australia. (Inkata Press, Melbourne).

Lazarides, M. and Hince, B. (1993). CSIRO handbook of economic plants of Australia. (CSIRO, Melbourne). #945.3.

Marchant, N.G., Wheeler, J.R., Rye, B.L., Bennett, E.M., Lander, N.S. and Macfarlane, T.D. (1987). Flora of the Perth Region. (Western Australian Herbarium, Department of Agriculture, Western Australia). P975.

Moore, J.H. and Wheeler, J.R. (2002). Southern Weeds and their Control. Photos.

Muyt, A. (2001). Bush Invaders of South-East Australia: a guide to the identification and control of environmental weeds found in South East Australia. (R.G and F.J. Richardson, Australia). P80-81. Photos.

Paterson, J.G. (1977). Grasses in South Western Australia. (Western Australian Department of Agriculture Bulletin 4007). P71-72. Diagram.

Acknowledgments:

Collated by HerbiGuide. Phone 08 98444064 or www.herbiguide.com.au for more information.