Table 3 Summary of main biotic and abiotic constraints on rice production
From: Farmers’ rice knowledge and adoption of new cultivars in the Tillabéry region of western Niger
Constraint name | Effect on rice | Causes | Time of infection | Control measures | Local names (LN) | Translation of LN |
|---|---|---|---|---|---|---|
Birds | Suction of spikelets | Birds, drought | Milk stage, maturity | Guardians (two rice bags/guardian/season | Sassa, Tsounsayé | Birds |
Bacterial leaf blight (BLB) (Xanthomonas oryzae spp.) | Drying and rotting of leaves, milky drops | Soil worms, unknown | Tillering, booting | Apply ash, pesticides, elimination of diseased plants | Bouharora, Wiharora, Goura | Kill in the water |
Borers (Chilo zacconius B.) | Drying of panicles, rotting of the ‘heart’ | Plant worms, butterflies | Booting, milk stage | Generally none, sometimes pesticides | Djindegoro, Bon kwaraye, kofo, Goro-goro, Kolo-wiyo | Neck sting, white head, ‘heart killer’ |
Drought | Drying and death of seedling | God | Seeding, tillering | Late sowing | Kogay | Drought, lack of water |
Flood | Rotting of plants and death | God | Seeding, tillering | Early sowing | Hari ngayan | ‘Eaten’ by water |
Hippopotamus (Hippopotamus amphibius L.) | Destruction of fields, feeding of plants | Overprotected by the government | From tillering to harvest | Guardians (60 USD/guardian/sector | Ba nga | Hippopotamus |
Pests | Injuries to leaves and spikelets | God, good rainy season | Booting, milk stage | Generally none, sometimes pesticides | A nga riya, doyzo, fara | Insects, grasshopper |
Rice yellow mottle virus (RYMV) | Yellowing of leaves, height reduction, blackish and empty panicles | Worms, high humidity, ‘white fertilizer’ (urea), unknown | Tillering after application of urea | Apply ash from millet glume and glumelles, drying fields, pesticides, elimination of diseased plants, sometimes none, inefficient | Ola, Olalo, Tiguiro, Larabo, Dori Sayo, Tchoukki, Bellayze tchira | The yellow one, the dwarf, the Arabic man, the Touareg man, the one with light complexion |
Salinity | Discoloration and death of leaves, yield reduction, low tillering | Salt in the soil | Anytime | Apply millet glume and glumelle, organic manure | Sosso | Bicarbonate |
Spiders (species unknown) | Trap seedling, reduce vigor | God | Seedling | Destruction of cobwebs, none | Dadara | Spider |
Unknown | Whitening of seedlings’ leaves | Unknown | Seedling | Apply ash, usually none | Kofa | Unknown |
Weedy rice (species unknown) | Invades fields, seed degeneration | Transformation of rice over time to wild rice | Anytime, but visible at heading | Elimination of invasive plants (usually young farmers could not differentiate from rice) | Sombay | Wild rice, O. barthii |
Whitefly (Aleurocybotus indicus D. and S.) | Honeydew on leaves and sheath | Flies, high density transplanting | Booting | Apply ash, drying fields, sometimes none | Katou, You | Honey |