The optimum weeding regime for thorny mimosa control in cassava established at 10,000 plants/ha was studied at Ibadan, Nigeria (7°22½′N, 3°50½′ E), a humid tropical environment. The study compared six weeding regimes, each comprising manual removal of thorny mimosa three times at different intervals within 13 wk after planting (WAP). Cassava vegetative growth recovered from thorny mimosa interference when the first weeding occurred within 5 WAP, but interference for more than 5 WAP reduced storage root yield. Allowing thorny mimosa infestation after 11 WAP had no effect on cassava growth or root yield. Manual removal of thorny mimosa at 4, 7, and 11 WAP consistently gave the highest cassava root yield.

Nomenclature: Thorny mimosa (or giant sensitive plant), Mimosa invisa Mart.; cassava, Manihot esculenta Crantz ‘TMS 30572’.

Additional index words: Canopy closure, cassava vegetative growth, storage root yield, weed interference.

Abbreviations: IAR & T, Institute of Agricultural Research and Training; MAP, months after planting; WAP, weeks after planting.