Common name - Thunessa
Botanical name - Cyperus iria
Family - Cyperaceae
Life cycle - Annual
Morphology
- A tufted annual herb, or occasionally perennial, with fibrous roots, 15 - 75 yellowish red roots; 10 - 70 cm tall
- Stem: sharply 3 angled, tufted, smooth, 5 - 80 cm high
- Leaf: basal, rough to touch in upper part, linear, flaccid, with gradually tapering point and 3 - 8 mm wide; sheath reddish or purplish brown, enveloping the stem at base
- Inflorescence: simple or compound umbel composed of numerous erect-spreading 3 - 10 mm long flattened spikelets
- Fruit: three-angled, 1.0 - 1.5 mm nut with slightly concave sides, and shiny dark brown to black.
Propagation
- By seeds
Agricultural usage/ importance
- Serious weed in rice
- Ovipositional host of the insects
Control method
- Cultural control
- Hand weeding at earlier stage of growth to prevent flowering and seed production
- Rotary weeding in transplanted rice during the seedling stage
- Chemical control
- Butachlor or oxadiazon after harrowing and sowing of rice and chlorimuron, propanil, or MCPA after emergence
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