Plantwise Factsheets for Farmers
Management of groundnuts to reduce aflatoxins
Recognize the problem
get contaminated with poisons, called aflatoxins. These poisons are produced
by several fungal plant diseases. These fungi are soil-borne, and can attack
the crop both in the field and after harvest. This can be a problem if a
farmer delays harvesting when the crop has already matured. The infected
groundnut plants in the field show symptoms of yellowing which can be
confused with other diseases. The major loss of quality occurs after harvest
when farmers are shelling by hand. The contaminated nut is difficult to
recognize but at heavy infestation it becomes greyish-green and is dangerous
to humans. It also loses its market value.
contamination is a problem for farmers who shell their groundnuts by hand as
they use water to soften the pods for easy shelling. This watering process
increases the chance of the nuts being contaminated with fungi and aflatoxins.
Using a manual groundnut sheller helps to prevent such contamination, thus preserving
the quality of the nuts. The sheller is fitted with a sieve which is changed
according to the variety of groundnut grown by farmers and is manually
operated. It is also portable to support more farmers. Dry conditions are the
most important factor to prevent fungal growth.
Maturity is confirmed by
pulling 2-3 plants out of the soil to check some of the nuts. Nuts are opened and checked inside the
shells for the presence of dark markings, original seed colour and texture.
This shows maturity.
- The harvested plants are
sundried for 3 weeks by hanging them on a rack in the field until they show
signs of dryness such as darkening of leaves, leaf drop and dry pegs with
- The manual groundnut
sheller is fitted with the right sieve for a particular variety and size of
groundnut to start shelling
- After shelling, nuts must
be stored dry
- No watering of nuts to
make them softer is allowed, as fungi may grow. Only directly before eating can
nuts be watered, washed, and cooked
- Other measures to reduce fungal diseases and aflatoxins include the use
of fungal-resistant varieties and proper land preparation. Crop rotation is
difficult because these fungal diseases have many hosts.
The recommendations in this factsheet are relevant to:
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