By Floyd Fambisai
Irish potatoes are shallow rooted tuber plant which matures at 3-5 months after planting.
The potato plant can be grown from Seed (TPS), plant parts like stems or tubers but most farmers plant from tubers
Soil and land preparation
Potatoes are be best grown soils which are rich in organic matter, have good drainage and aeration of pH 5.0 – 5.5 and are loose which allows tuber enlargement.
Irish Potato should not be rotated with crops like tomato, tobacco as nematodes could be controlled by the use of clean seed and crop rotations.
It matures at 19 weeks and flesh tubers yield 40 t/ha
It matures at 15 weeks Yield 25 t/ha
It matures at19 weeks, good variety a for processing with yield 20 t/h
It matures at 19 weeks and a good yielder 60 t/ha
Seed rate and Spacing:
Potatoes needs a seed rate of 3 t/ha using spacing 90 cm between rows and 40 cm in-rows
Potatoes are first spouted before planting and this is done in daylight conditions under shade.
It is recommended to use compound S at rate of 1300-2100 kg/ha and top dressing of 100-150 kg/ha and application of AN at 1-3 weeks after the crop emergency
Time of Planting
Potatoes are grown all year round except in winter in Lowveld areas.
Irrigation should be done to field capacity regularly until maturity but avoid foliage contact as it encourages fungal infections mainly in the Lowveld areas.
Hand and mechanical weeding should be reduced as potatoes are shallow rooted crops. Earthing up by ridging around the plants should be done to protect the tubers from exposure to direct sunlight and tuber-moth as part of weed control also one can use herbicides Dual and Sencor
Normally harvesting is done when 95% of the leaves have died. Clean pest free tubers should be dressed with 1% malathion and store in a clean room
Pests and diseases
Soil pests which are difficult to control and may be controlled controlled by rotation with nematode resistant grasses like Katambora Rhodes and Sabi Panicum, and through soil fumigation with Nemacur which should be done four weeks before planting.
Potato tuber moth
The larvae of this pest cause leaf damage by tunnelling leaf surface, stems and the tubers can be controlled through good field sanitation.
Green to brown small insects which suck sap from leaves and also transmit several virus diseases such as Leaf roll, Necrotic Virus Y and Virus Y.
Small larvae which cuts the plant at its base
Late blight,Early blight
Bacteria diseases which can cause very big loses and the best control measure is to plant tolerant varieties and field sanitation.
• Leaf roll
• Black heart caused by storage at high temperatures
• Hollow heart irregular growth due to irregular irrigation
• Internal browning prevalent acidic and phosphate deficient soils