Thunessa Cyperus iria

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