Synonymes : Paspalum paspaloides (Michx.) Scribn.
Common name : Knotgrass
Common name in Hindi : Besak
Common name in Urdu : Naru ghas
Bangla English Hindi Urdu
Diagnostic characters
Biology
Ecology and distribution
Nuisance
Weed control
Botany
Uses/Remark
References
Paspalum distichum is a perennial grass growing up to 30cm tall; sometimes it may forms large plant communities. Stems are prostrate at the base, occasionally more than 1 m long and rooting at the nodes. The linear leaves enclose the stem at the base by the leaf sheats that have their upper margins covered with white hairs. The inflorescence is compound of 2 opposite racemes initially erect and later spreading.
This grass mainly propagates vegetatively by fragments of stolons and in some cases by seeds, which are rarely viables.
P. distichum is distributed in the tropical and subtropical regions of the world, but its origin is unknown. It grows in humid to wet areas, open to slightly shaded sites, often along polluted waters in villages, sometimes aquatic. Present from 0 to 1500m altitude.
P. distichum is a serious weed in direct seeded rice; it invades rice fields to become a weed, growing vigorously which can not be controlled easily. It is a major weed in Pakistan, in Punjab region, where it rushes into the fields from the field boundaries.
- Cultural
The intrusion of this weed into rice fields may be restricted through hand pulling of initial sprouts from the field boundaries one month after plantation. But manual control is difficult because of the easily regenerating fragments.
- Chemical
In India, pre-emergence application of butachlor at 1.5 kg/ha, Anilophos at 400 g/ha, Pretilachlor at 1.0 kg/ha.
In Pakistan, use of pre-emergence herbicides like Machte 60 EC at 2.5 l/ha, Acetor 50 EC at 250 ml/ha and Topstar at 100 mg/ha may prevent seed germination of water grass in rice. Utilisation of Gramoxone 20 EC at 2.5 l/ha or Glyphosate (Fix up 41 SL) at 5 l/ha in water courses. Spray may be repeated twice within a summer season.
Habit
Perennial weed growing up to 30cm tall, usually shorter, with long, stout, creeping, branched stolons.
Roots
Fibrous roots and adventitious roots profusely branched at basal nodes.
Stem
Culms erect, glaucous, geniculate, with nodes thickened, usually hairy.
Leaves
Blade linear, attenuate acute, glabrous or sparingly hairy, ciliate near its base, 5 to 15cm long and 2 to 8mm wide. Sheath glabrous, mouth long ciliate, ligule membranous, truncate, and fringed, 2 to 3mm long.
Inflorescence
Compound of 2 opposite racemes initially erect and later spreading, 2 to 9cm long pseudo spikes (racemes); rachis flat, 0.5 to 2mm wide; spikelets solitary, flat on one side, convex on the other side, elliptic to ovate oblong, acute, 3.5mm long, with one bisexual flower, articulate with the very short pedicels, falling off as a whole.
Fruit
Caryopsis ellipsoid, compressed, yellowish to light brown.
- Soerjani M., Kostermans A. J. G. H., Tjitrosoepomo G. 1987. Weeds of rice in Indonesia. Balai Pustaka. Jakarta.
-Harada J. and Association for international cooperation of agriculture & forestry. 1996. Weeds in the tropics. Association for international cooperation of agriculture & forestry, Japan. 304p.
- Nayyar M. M., Ashiq M. and Ahmad J. 2001. Manual on Punjab weeds (Part I). Directorate of Agronomy. Ayub Agricultural Research Institute, Faisalabad Pakistan.
Top of the page