Farmers can control blossom end rot in tomatoes by adding crushed egg shells to their plants and watering at least thrice a week.
According a research by agronomists in East Africa at the Kenya Agricultural and Research Organisation, egg shells have calcium that helps in boosting root and leaf growth and maintaining 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 with a 20 to 30 per cent loss rate,” said KALRO crops researcher Mirima Otipa.
“The disease is characterised by round –brown water-soaked spots on the blossom end of the fruit. Test the soil in your farm for calcium levels one to two months before planting,” Otipa says.
How it works
Farmers should harden their seedlings two weeks before transplanting. This involves exposing the seedlings to sunlight, wind and temperatures outside the nursery bed seven to 10 days before transplanting.
While transplanting, boost calcium levels in the soil by adding crushed egg shells (12 grammes of eggshells/plant) and bone meal (250 grammes/hill) in the planting hole.
Eggs shells can be obtained from chicken keepers or collected at the farm level for those farmers keeping poultry. You can also get the shells from hotels and roadside rolex dealers.
After planting, water your plants three times per week to ensure an adequate amount of moisture and steady growth of the plants.
To conserve soil moisture, apply mulch cover 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.
Top dress the plants with calcium ammonium nitrate (26 per cent Nitrogen) at knee high at a rate of 40 kilogrammes/acre then at flowering 80 kilogrammes/acre.
CAN is sold at Shs100,000 per 50-kilogramme bag and is obtained from certified agrovets.
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 30 grammes in 20 litres of water every 7 to 10 days when fruits are about two centimetres in diameter.
After every three years, add lime to your farm with calcium carbonate at 150 grammes per square metre.
What does blossom end rot look like?
The bottom side of the tomato (either a green or ripened one) develops a sunken, leathery dark brown or black spot. Farmers most often notice BER when fruit is 1/3 to 1/2 its full size.
What causes it?
A calcium imbalance. A tomato’s cells need calcium to grow. Calcium acts like glue in cells – it binds them together.
Tomatoes absorb calcium through water. But calcium is not fast-moving. f a tomato grows quickly, or if other conditions slow water absorption, then calcium does not have enough time to travel through the whole piece of fruit. Plants can’t absorb enough calcium – whether or not there is enough in the soil.
How can you prevent blossom end rot?
There are lots of ways you can take precautions for next year’s crop.
•Carefully harden off young seedlings gradually to protect them from extreme temperatures and conditions.
•Select a planting area with good drainage.
•Avoid setting out plants too early in the season, which can expose them to cold temperatures and cold soil. Allow soil to warm before planting.
•Work in plenty of compost and organic matter into the soil before planting, so that the plant’s root system has a better chance to grow strong and deep.
•Add quick-release lime when planting tomatoes so that there’s plenty of calcium in the soil and it’s absorbed quickly. Tomatoes grow best when the soil pH is about 6.5.
•Keep your tomatoes’ water supply even throughout the season so that calcium uptake is regular. Tomatoes need 1-3 inches of water a week. They perform best when watered deeply a couple of times a week rather than superficially every day.
•Mulch plants once established to maintain moisture levels.
Once blossoms emerge, apply tomato fertiliser that is high in phosphorus (the second number in a fertiliser’s three-number series), such as 4-12-4 or 5-20-5.
•Too much nitrogen (the first number) or large amounts of fresh manure can prevent calcium uptake.
•Cultivate carefully around tomato plants to avoid damaging root systems. Try not to dig more than an inch or two deep around plants.