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Graminae
Common names
Crow's foot grass (Australia), goose grass (United States),
grama de caballo (Cuba), pate de gallina (Peru), rapoka grass, crab grass
(South Africa), Indian goose grass, kavoronaisivi (Fiji), mangrasi (Suriname).
Description
Coarse, caespitose annual, branching at the base, 30-60 cm
tall, the culms ascending or prostrate, smooth, compressed; leaf-sheaths
smooth, blades linear, flat or folded, 3-8 mm wide. Two to six spikes,
digitate, sessile, 4-15 cm long, with usually one inserted lower on the
culm, the rachis prominently flattened with the spikelets loosely imbricate
and secund. Spikelets sessile with three to 15 flowers, 3-4 mm long. Glumes
rather unequal, the lower narrow, oblong, obtuse, one-nerved, the upper
lanceolate or ovate-lanceolate, three-nerved, rather acute. Lemmas lanceolate,
rather acute, sometimes keeled, 3 mm long. Pericarp persistent, very loose
and membranous, enclosing the rugose seed (Gardner, 1952). Distinguished
from Chloris and Dactyloctenium by having awnless spikes. It has a particularly
tough root system and is hard to pull out. Subspecies africana is a tetraploid,
larger, with larger spikelets and a ligule that has a definite ciliate
fringe (Chippendall & Crook, 1976). At low densities it can compensate
by producing more tillers (Jones & Aliyu, 1976).
Distribution
Tropical and subtropical regions.
Season of growth
Summer.
Altitude range
Sea-level to 2 000 m.
Rainfall requirements
It commonly grows in the 500-1 200 mm rainfall range.
Drought tolerance
Its extensive root system allows it to forage for moisture
well during its annual growth.
Tolerance to herbicides
To control this grass use cultivation, but if chemical control
is needed use a pre-emergent spray of 2,4-D sodium salt at 9.5 kg/ha of
an 840 g AI/kg product (e.g. Hormicide). No wetting agent is required when
used as a pre-emergent spray. Use a minimum of 340 litres of water per
hectare. Seedlings up to the four-leaf stage can be controlled by paraquat
at 570 ml of a 200 g AI/litre product (e.g. Gramoxone) per 200 litres of
water plus a surfactant at 250 ml/200 litres water. Spray until spray material
runs off leaves (Tilley, 1977). In lawns in the United States potassium
thiocyanate and disodium methylarsonate are recommended as effective control
measures (Ivens, 1967). E. indica was killed in P. maximum and B. decumbens
pastures on the Atherton Tableland, Queensland by atrazine above a strength
of 0.9 kg AI/ha (Hawton, 1976). Setaria sphacelata seed crops can be selectively
rid of E. indica by pre- emergence treatment with methabenzthiazuron at
1-2 kg/ha. S. sphacelata is susceptible to atrazine, simazine and terbutryne
(Hawton, personal communication), Jones and Aliyu (1976) had some success
with pre-emergent spraying of trifluralin at rates of 0.56 kg/ha AI in
Leucaena leucocephala but yield of the legume was affected. Activated charcoal
and Dacthal gave some control but more research is needed to clarify the
effect.
Seedling vigour
Seedlings have exceptional vigour and quickly establish themselves.
Vigour of growth and growth
rhythm
On the Atherton Tableland vigorous growth occurs between 8
September and 16 January at the expense of Setaria sphacelata seed crops
(Hawton, 1979).
Suitability for hay and
silage
It can be made into coarse hay and silage.
Toxicity
It often contains prussic acid (Cyanogenetic glucoside), the
main concentration being in the seeds varying from 0.015 to 0.019 percent,
just below the theoretical potential danger level (Everist, 1974).
Cultivars
There are no cultivars registered. Bogdan (1977) records a
subspecies africana (Kennedy and O'Byrne), Phillips, a more robust form,
a tetraploid with 2n=36, from East Africa occurring at higher altitudes
than ssp. indica.
Main attributes
Its aggressiveness and its easy establishment for stabilizing
sandy soils.
Main deficiencies
Its problem as a weed, its occasional toxicity.
Optimum temperature for
growth
The optimum mean temperature for seed germination was 23°C
at Kairi (lat. 17°18'S, altitude 700 m) on the Atherton Tableland,
Queensland (Hawton, 1979).G
Minimum temperature for
growth
Hawton (1979) found mean temperatures below 23°C restricted
germination, but it could occur at temperatures as low as 20°C.
Palatability
It is eaten when young; when older the foliage is very tough.
Natural habitat
Widespread weed of disturbed land.
Genetics and reproduction
2n= 18, 36 (Fedorov, 1974).
Economics
A worldwide weed of the tropics. It is one of the worst weeds
of maize in Zimbabwe and South Africa (Ivens, 1967). It is the major weed
problem in swards of Panicum maximum, Setaria sphacelata and Brachiaria
decumbens grown for seed production on the Atherton Tableland, Queensland
(Hawton 1976, 1978) and in the establishment of the browse legume Leucaena
leucocephala at Samford, Queensland (Jones & Aliju, 1976). In India
the seeds of E. indica are eaten by humans in times of drought.
Animal production
No figures have been cited.
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