YAM (Dioscorea spp)
Yam belongs to the family Dioscoreacae. It is a root and tuber crop popularly grown in West Africa
and it is rich in carbohydrates.
Land Preparation of Yam
1. Preparation of the land or soil
If you have about one hectare of land, you will have to prepare the soil for planting the yam seeds. It is necessary to clear bushes and grasses before rainy season if there are any.
The weeds would be allowed to dry up with the soil to form organic manure. The months of February and April are best to plant yams when the rainy season is just beginning.
Cutlass is used toridges or mounds are made with hoe. It can also be done by ploughing, harrowing and ridging mechanically.
Varieties Of Yam or Cultivers
Important varieties include:
(i) Dioscorea rotundata – white yam
(ii) Dioscorea alata – water yam
(iii) Dioscorea bulbifera – aerial yam
(iv) Dioscorea cayenesis – yellow yam
Dioscorea domentorum – bitter yam 1.
Dioscorea rotundata (white guinea yam – common in Nigeria),
Dioscorea alata (yellow yam – common in Nigeria)
Dioscorea bulbifera (aerial yam),
Dioscorea esculant (Chinese yam) and
Dioscorea dumetorum (trifoliate yam).
Climatic and soil requirements for Yam Cultivation :
Yam requires a temperature of 25C – 30C; rainfall of between 100cm – 180cm per annum: abundant sunshine and a well-drained sandy-loamy soil, rich in humus.
Method of propagation of propagation of yam and the propagation materials :
Yam is propagated by the following materials: yam setts, yam seeds or yam mini-setts.
Seed rate of yam:
one seed yam or sett per hole; three to five tones of seed yam per hectare is required.
how to Plant yam :
Open a hole on the heap. Place one yam sett inside with the cut surface turned upward and slantly place at an angle of 45 before covering it with soil. They cut yam sett should be dried under the sun and dusted with chemicals such as aldrin dust before planting. This prevents rottening and pest attack of the sett.
Spacing is 90cm x 100cm, while yam mini-setts is 25cm x 100cm. sprouting occurs three to six weeks after planting.
Cultural practices in the propagation of yam
read details of cultural practices in agriculture here
(i) Mulching: This is the covering of the heaps or ridges with dry leaves to reduce soil temperature, conserve soil moisture and prevent rottening of yam setts.
(ii) Regular weeding: this should be done regularly to control pest and reduce weed competition with crops for nutrients.
(iii) Application of fertilizer: Apply 200kg (four bags) of N.P.K. fertilizer per hectare three months after planting, by ring method.
(iv) Staking: The yam should be staked with strong sticks or bamboo. It ensures adequate exposure of the leaf surface to sunlight and increases yield.
(vi) Training of vine: This is done regularly after staking to ensure even spreading and neatness of the vines to receive sunlight.
Period of Maturity period of Yam:
Yam matures in 8-12 months after planting.
Process of Yam Harvesting:
Dig the soil gently with cutlass to remove tuber from the soil. Processing: Yam tubers are processed into yam powder or flour or consumed locally.
Yam tubers are stored in barns. It can also be stored in form of yam flour and in dried peeled yam tubers.
read types farm storage here
Pests of Yam
(1) Yam tuber b makes holes on tubers, resulting in low tuber marketability.
(i) Apply insecticide like BHC at planting
(ii) Dust yam sett with aldrin dust
(iii) Practice crop rotation
(2) Yam shoot beetles: Young larvae cluster on vine tips. Adult feed on yam leaves and cause vine to die or defoliate.
How to Control pests of yam
(i) Spray yam plant with insecticides e.g. BHC
(ii) By hand picking
(iii) Dust with chemical like Agrocide 3 powder.
(13) Rodents: Rats and rabbits eat up tubers
Control: Set traps to catch the rodents.
Diseases of Yam
(1) Yam mosaic disease: It is caused by a virus which is transmitted by a piercing and sucking insect.
Symptoms: Symptoms include a mosaic pattern and chlorosis of leaves. It cause stunting of affected plant.
How to Control diseases of Yam
(i) Grow resistant varieties
(ii) Spray with insecticides
(2) Yam rot: It is caused by bacteria which are spread by splashes of rain and insects.
Symptoms: Liquid oozes out from infected tuber. White – brown liquid emits with punget odour.
(i) Destroy all affected yam
(ii) Apply aldrin dust
(iii) Practice crop rotation
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