How to control blossom end rot in tomatoes

According to a research done by the Kenya Agricultural and Livestock Organization (KALRO), tomato farmers can control blossom end rot in their crops by carrying out soil analysis annually to determine calcium levels and watering of their crops regularly.

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Calcium has a specific key influence on tomato fruit quality as it boosts root and leaf growth and maintains good fruit firmness and quality thereby reducing blossom end rot risks.

Blossom end rot is a troublesome disease, familiar to most farmers who have grown tomatoes. According to KALRO crops researcher Mirima Otipa, the demand for fresh tomatoes is high both for domestic use and markets. However, tomato post-harvest losses are a threat to the harvested tomatoes. Farmers in Kenya have reported 20-30% losses due to infestation by the disease.

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A tomato fruit affected by blossom end rot disease

Blossom end rot in tomatoes is characterized by round –brown water-soaked spots on the blossom end of the fruit. Before planting of tomatoes there is need for farmers to test soil in their farms for calcium levels 1-2 months before planting.

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The seedlings should be hardened 2 weeks before transplanting. While transplanting, boost calcium levels in the soil by adding crushed egg shells (12g of eggshells/plant), bone meal (250g/hill) in the planting hole.

 After planting, the plants should be watered regularly at least three times per week to ensure an adequate amount of moisture and steady growth of the plants. To conserve soil moisture, mulching should be done using maize stover, wheat straw or dried grass. Mulching is important especially at the flowering and fruiting stage as the plants need maximum moisture for optimum yields.

Farmers can test the soil moisture by picking and pressing soil between the fingers. If the soil particles do not stick to each other, it shows the soil is dry hence the need to initiate direct control.

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The tomato plants should be top-dressed with calcium ammonium nitrate (26%N) at knee high at a rate of 40kg/acre then at flowering 80kg/acre, farmers should ensure there is adequate soil moisture during application.

As the fruits mature farmers should look out for small water-soaked sunken spots at the blossom ends of the fruits which enlarge and darken as the tomatoes grow. Spray with calcium nitrate or calcium chloride at 30g in 20 liters of water every 7-10 days until 3- 4 applications prior to onset of symptoms when fruits are about 2cm in diameter. After every 3 years, liming should be done on the farm with calcium carbonate at 150 g per m2.

Quality fresh tomatoes in Kenya can earn farmers up to Sh. 500,000 per acre.

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  • When applying fertilizers always wear protective clothing
  • Follow instructions on the label such as dosage, timing of application and maximum number of applications
  • Dispose of excess fertilizer properly to avoid aquatic contamination

The price of a 64 kg crate of tomatoes at current market prices in various towns range from Sh. 2200 to 2500 according to Soko+, a digital commodity trading and information system, linking small scale farmers to end retailers/bulk purchasers of produce.