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Graminae
Synonyms
D. vestita Fig. & De Not. var. scalarum Schweinf.; D. scalarum
(Schweinf.) Chiov.
Common names
African couch grass (Tanzania), couch finger grass, Dunn's
finger grass (South Africa), thangari (Kenya).
Description
Perennial with slender long rhizomes and erect culms up to
30 cm high; leaf blades 3-5 mm wide, but on occasions up to 7-8 mm. Panicle
of two to nine racemes, often whorled and sub-erect, 2.5-8 cm long with
broadly elliptic, completely glabrous obtuse spikelets 2 mm long (Napper,
1965). The rhizomes form a dense mat beneath the soil surface, extending
to depths greater than 1 m, and may twine around the roots of perennial
crops (Terry, 1974). It differs from Cynodon dactylon in the vegetative
stage in having an obvious membranous ligule where the leaf-blade joins
the sheath (Ivens, 1967).
Distribution
Native to Zaire and eastern tropical Africa.
Altitude range
Sea-level to 3 000 m.
Rainfall requirements
It prefers more humid areas. Common near Bukoba on shores of
Lake Victoria, west Tanzania. Rainfall should be in excess of 500 mm.
Tolerance to herbicides
Terry (1974) found glyphosate (Round-up) at 2 and 4 kg/ha and
at split applications of 1 + 1 and 2 + 2 kg/ha gave very good control of
D. abyssinica foliage but 1 kg/ha was less effective. Asulam at 2,4 and
8 kg/ ha gave poor control. Dalapon at 5 kg/ha gave moderate control which
was improved by 0.5 kg/ha paraquat applied 51 days after treatment with
dalapon. Prolific growth of annual broad-leaved weeds occurred where D.
abyssinica had been controlled with glyphosate and dalapon and these would
need subsequent control. Richardson (1967) obtained success in Kenya sisal
plantations with heavy applications of sodium trichloro-acetate (Na-TCA).
It was successfully controlled in Zambia coffee plantations by running
poultry intensively (Chippendall & Crook, 1976).
Dry-matter and green-matter
yields
Richardson (1967) reported fresh weight yields of D. abyssinica
from sisal land of 36 t/ha which caused substantial fibre losses in the
sisal.
Palatability
Fairly palatable when young, but unproductive. It was accepted
by Ankole bullocks in the wet season in Uganda, but not in the dry season
(Harrington & Pratchett, 1972).
Chemical analysis and
digestibility
Dougall and Bogdan (1960) record 14.7 percent crude protein,
29 percent crude fibre, 9.5 percent ash, 3.8 percent ether extract and
43 percent nitrogen-free extract in fresh material at the early bloom stage.
Verboom and Brunt (1970) recorded 8.69 percent crude protein, 31.48 percent
crude fibre, 3 percent ether extract, 6.17 percent ash and 50.66 percent
nitrogen-free- extract from flowering material in Zambia.
Natural habitat
Grassland, and as a weed in plantation crops.
Genetics and reproduction
2n=36 (Fedorov, 1974).
Economics
The grass is often a troublesome weed in cultivations, in plantations
and in orchards. It has been planted on the slopes of the Cape Peninsula
in Africa to control erosion (Chippendall, 1955). The most troublesome
of all African weeds (Ivens, 1967). It is, however, used in leys at Nemalonge,
Uganda, in cotton rotations.
Further reading
Ivens, 1967.
Value for erosion control
It has been planted on the slopes of the Cape Peninsula in
Africa to control erosion (Chippendall, 1955).
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