Tomatoes are an important commercial crop for horticulture farmers in Kenya. The market is strong, and the crop is relatively easy to grow. It is a favourite for greenhouse farmers. The most important factors for success are:
- Deep, well-drained soils
- High producing and resistant varieties
- Proper staking
- Control of disease (Blights and Cankers)
Tomatoes require temperatures from moderate to hot, and humidity moderate to high. Rainfall should be moderate. These conditions are best achieved through irrigation or under greenhouses where possible. They do not do well in cool or soggy conditions.
Preparing Seed Bed:
Tomatoes perform better when transplanted from a seedbed nursery. They perform better when planted in trays where possible. Preparing a good nursery seedbed is important to ensure good plant establishment and vigorous early growth.
Seedbeds are prepared by raising soil around 15cm high and leave spaces for walkways of around 30cm or more between beds. The soil should be tilled. This is to make it easier for the small seeds to break through. As a precaution against nursery damping off and to give them a boost, soak the seeds in a mixture of AFRIKELP (2ml/litres of water) and RODAZIM (1ml/ltr of water) for 4 minutes before sowing. The seeds should not be buried deep into the soil but should be covered with a very light layer of soil. You can use your finger to draw the lines in which you plant the seeds and covered just slightly with soil.
The spacing between rows should be around 15cm. To increase moisture level, the bed is covered with hay or dry grass. This also reduces splash effect during watering.
Watering is best done in the morning. The seeds are expected to sprout in 8-10 days. The watering should continue until a week or two before transplanting where it is reduced to harden the seedlings. Seedlings will take about one month before they are ready for transplanting. Scout regularly for pests and diseases, because the earlier they are spotted and treated, the better the survival rate.
2 days before removing seedlings from the nursery, apply AFRIKELP (2ml/litre) to the seedlings. This will ensure a faster recovery from transplant shock. Transplanting should be done when seedling stems are between 4-6 mms diameter, or at about 1 foot high. Avoid planting weak and diseased plants.
Ensure the field is free from weeds before planting by applying ROPHOSATE at 200ml/20ltrs.
Plant the seedlings at a spacing of 45cm by 60cms. Dig the planting holes to a depth of 6 inches. If you apply manure, carefully incorporate into the soil before planting. Apply DAP fertilizer at a rate of 80kg per acre. Treat the soil for soil-borne insect pests and soil fusarium wilt by drenching with a mixture of IMAXI 15ml/20Ltr and RODAZIM 20ml/20ltre of water.
Remove the seedlings from the nursery bed after watering well. Keep them in a shaded place, away from direct sunlight. Plant one seedlings in each hole and cover the roots with soil firming the soil around the roots. Water well but not excessively.
Fertiliser application, irrigation and weeding:
Top-dress the plants after 4 weeks with CAN or UREA at 50kgs per acre. Keep the field free from weeds particularly in the first 30 days. Avoid hand weeding as this may destroy the delicate roots. Apply AMBAR at 30ml/20ltrs between the rows and plants, to suppress any seed weeds before they sprout, and to kill any growing broad-leafed weeds. Use the appropriate nozzle for best results. AMBAR works best when weeds are not higher than 4 inches and smaller than the tomato plants.
During flower set, apply another dose of AFRIKELP 20ml/20ltrs targeting the flower buds. You can also mix with soluble foliar fertilisers which have high potassium and calcium. This will avoid calcium end rot and other related fruit diseases later on, as well as protect against flower/fruit abortion. After flower set, avoid fertilizers which are rich in nitrogen, eg CAN, NPK, Urea.
Irrigate to keep the soil moist, without being soggy or muddy. An irrigation cycle of twice a week using 10,000 to 20,000ltrs per acre is usually sufficient for tomatoes.
Pest and Disease Control:
Scout for signs of Blight, Mildew, Canker. Be careful especially during cool wet conditions when blight is most active. Apply an early spray of MILOR 50gms/20ltres as a precaution against blight, and repeat after 7 days if conditions are cold and wet. Scout for any signs of disease after this, and apply MILOR in weekly intervals if noticed. Mix every application with AFRIKELP 20ml/20ltrs to aid plant vigour, and recovery from stress.
Check for signs of insect damage every day particularly in warm dry conditions. The most serious pests include spider mite, leaf minor (tuta absoluta), thrips, whitefly, caterpillars and aphids. All of these can cause serious damage and should be controlled as much as possible. Also, check vegetation around edges of the field.
Spray JACKPOT 12.5 ml/20Ltr to control aphids, and worms, particularly at fruit set, before the moths can lay their eggs on the fruits. Spray a mix of ROMECTIN 20ml/20ltre, and IMAXI 12.5ml/ltr to control stubborn leaf minors and red spider mites. Spray BAMAKO 5gms/20ltrs on the crop in the evening and around the edges of the field to control whitefly.
Staking and pruning:
This is done by tying a plant vertically using a string and poles. Two poles are connected using a wire and plants suspended using strings that are tied to it. This method increases the productivity of tomatoes as compared to traditional open-air methods. The plants grow vertically having several fruit clusters along the stem. Support should be done early after transplanting when the plant is still young to avoid stem damage/breaking later on.
Pruning is removing side shoots, old leaves, diseased leaves and laterals. This should be done weekly to remove side shoots before they develop. Weeding should be done regularly as weeds compete for nutrients with the plants
Apply AFRIKELP 40ml/20ltr after each pruning or staking operation, to aid the plant recover from shock.
The tomatoes should be ready for harvesting as from the 70th day onwards depending on the variety planted. Remove the ripe fruits from the stems carefully and place in clean disinfected containers ready for transport.