Potatoes (Solanum tuberosum)
Local names in Kenya (Viazi,, Rabuond, Waru)
Potato is a starchy root vegetable important as a staple food and a source of farm incomes. The crop is a major foodstuff in Kenya. Whereas there is a general increase in the land area under potato cultivation, total national production has remained steady or declined over recent years. Kenya has produced Potato Growing Regulations 2018 which can be referred in conjunction with information provided.
Potatoes require altitudes of 1500 – 3000 masl
Soil type and conditions
Soils should be deep minimum 30 cm, well-drained, fertile, medium loam, preferably gentle sloping land, on mild slopes, ridges should more or less follow the contour with a small longitudinal slope to allow for drainage
The pH should be 5.5 – 7.5, high soil pH causes scab disease and liming is recommended before planting if pH is below that range. Potato nutrient requirements include: N, P, K, Mg, Ca, S, Zn, Cu, Mn, B
The temperatures should be 20-25oC
The rainfall should be more than 750 mm p.a.
Steps during land preparation
1. Plough when soil is dry
2. Plough the farm to appropriate tilth 45cm-50cm deep
3. Add manure and fertilizers to the soil in the right amounts to provide the required plant nutrients for vigorous crop growth
Seeds should be obtained from dealers, where they have been well-graded and are uniform in size.
Since potato seed is too expensive, growers can use seed stock system
Planting materials should be well-adapted to emerging local climatic and environmental conditions
As an alternative option, establishment of raised beds for rooted cuttings or seed plot system that uses raised beds
Rooted cutting system
A system that involves planting of rooted cuttings on raised beds at 30cm by 30cm which develops into small tubers that can be used for further multiplication for further use as seeds
Seed plot system
A system of multiplying potatoes by planting the seeds on raised beds at 30cm by 30cm and harvesting for use as seeds after 3-4 months
General : Kenya Baraka, Roslin tana, Roslin Gucha, Kerrs Pink, Roslin Eburu (B 53), Desiree, Feldeslohm, Kenya Dhamana, Chaguo, Furaha, Romano, Dutch Robin, Shangi, Pumpernet
Current : Tigoni, Asante, Kenya Karibu, Kenya Mpya, Kenya Sherekea, Shangi, Arka, Kabale from Uganda
Imported varieties : Jelly, Karuso, Connect
Others: Unica, Primera, Rudolf
Plant at 5-15 cm depth but deeper and 30-40cm for white varieties under warm dry conditions
Place tubers with sprouts facing up
For consumption purposes, plant at a spacing of 75cm x 30 cm between rows and 30-40 cm within rows
Seed rate for tubers is 2-2.5 tons per ha. Seed rate depends on soil fertility status, rainfall availability and tuber use
The larger the seed size, the more the amount required
Make wider ridges or mounds if intercropping with annual crops e.g. maize and legumes
For seed potatoes, plant at a spacing of 15-20cm within rows, at 50kg bags per acre
Minimal water is required during normal vegetative growth of the crop
Irrigate during dry spell without over watering that leads to build-up of fungal diseases and poor aeration
Avoid irregular watering for it causes splitting of the tuber
Avoid weeding after flowering because it predisposes the crop to infections and may injure the tubers.
Add manure and fertilizers to the soil in the right amounts to provide the required plant nutrients for vigorous crop growth.
Rotate after every 4 years with non-root and tuber crops, preferably cereals and legumes to break pest and disease cycle such as carrot and improved fallow either under Crotalaria ocroleuca or Leucaena and brassicas
Earthing up should be done at 2-4 weeks after emergence to; enhance for tuber expansion, control potato weevil and prevent greening.
Potato pests include;
Aphids, White flies, Tuber moth, Nematodes Potato Cyst Nematodes (PCN) and Root knot nematodes, Cutworms, and Leaf minor and thrips
Notato Cyst Nematodes (PCN)
Pests control strategies
- Certified seed
- Test for potato cyst nematodes (PCN) on soils before planting
- Integrated Pest Management (IPM), including use of repellents
- Crop rotation to observed closed season for crops in Solanacea familyField sanitation, including removing harvest residues
- Organic pesticides (Bio-T-Plus)
Bacterial diseases included; late and early blight, bacterial wilt, verticillium wilt, soft rot and black scurf.
Viral diseases include; potato leaf roll and yellow virus, common scab, powdery scab and wart
Disease management strategies
- Plant; resistant varieties, certified and clean seed
- Conduct bacterial wilt and nematode (PCN) test are crucial before planting
- IPM with enhanced scouting
- Field sanitation/hygiene is more important; clean field, remove of harvest residues plant new fields away from old fields
- Remove diseased plantsDo not use diseased plants in compost
- Crop rotation with non-solanaceaous crops
- Spray with recommended fungicides to control blight under IPM program
- Test for bacterial wilt through KALRO or KEPHIS
Drying leaves is an indicator of maturity.
Harvest 7-14 days after dehaulming by digging up the tubers carefully using a forked jembe to avoid damaging them
They are then dried for a short period of time in rows before gathering them
Potato will produce up to 40tons per ha or 16tons per acre with proper management.
Packed potato intended for market are transported using bicycle, pick-up, lorries, depending on destination. The produce should be transported during the coolest part of the day
- Clean soil from the potatoes without bruising the skin
- Overstacking should be avoided during transpotation
- Sorting is done to remove rotten, damaged, malformed and weevil infested potatoes, and debris
- Grading is based on size, shape, colour, weight, maturity, market demand
- Potato is packaged in baskets, sacks, crates, depending on distance of transportation Potatoes in gunny bags/sacks be packaged in 50kg and below
Potato can be processed to make potato Crips and French fries.