Plantwise Factsheets for Farmers
Minerals against blossom end rot in tomato
Recognize the problem
end rot is not a disease. It is a plant disorder caused by a lack of calcium in
the flowers and fruits. The first symptoms of end rot are a water-soaked area
near the blossom scar of the fruit. This area later develops into a larger, tan
to brown, leathery lesion. Fungi often colonize these lesions, which make
them grey to black and velvety. Although blossom-end rot is often seen on mature
fruits, young, rapidly growing fruits are most endangered by calcium
end rot is a result of insufficient calcium uptake by the plant. This usually
occurs as a result of quick changes of periods of wet and dry soils. Other factors
are boron deficiency, high salt content in the soil, irregular or over
irrigation, high fruit load, or too much nitrogen. Foliar-sprayed fertilizers
with calcium and magnesium can be used against this disorder. CALMABON is one
of these fertilizers and contains Nitrogen, Calcium, Magnesium, Boron and
Molybdenum, all of which are needed by the plant. For comparable products,
contact local agro-input dealers.
Ensure the plants always
have a good supply of water
- Buy your CALMABON Plus or comparable
calcium-magnesium fertilisers for vegetables from a registered agro-dealer
- Use 500 ml - 1600 ml CALMABON-Plus
per 100 litres of water, translating to 5 to 8 litres per hectare. This means
100ml - 320ml of CALMABON-Plus per 20 litres of water of knapsack
sprayer. But double check product label
for dosage instructions, as products may differ.
- Add 2 tablespoons of
sticker (teepol/any liquid soap) per 20 litres to allow the mixture to stick
on the leaves. Mix properly.
- Use fine flat spray
nozzles, to apply a full coverage foliar spray.
- Make first spray at
flowering stage and repeat every second week, if required. Do not spray at shorter intervals than
- Spray especially when
plant transpiration is reduced by factors like changes in temperature (warmer
- Spray mid-morning
when there is no dew or late afternoons when there is no wind.
The recommendations in this factsheet are relevant to:
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