Cookies on Plantwise Knowledge Bank

Like most websites we use cookies. This is to ensure that we give you the best experience possible.


Continuing to use means you agree to our use of cookies. If you would like to, you can learn more about the cookies we use.

Plantwise Knowledge Bank

Your search results

Plantwise Factsheets for Farmers

Aflatoxins in maize

Aspergillus flavus; Aspergillus parasiticus

Recognize the problem

Aflatoxin is a poison produced by moulds ("mbuu") that grow on maize and other products such as peanuts and rice. Maize in Kenya is highly susceptible to Aflatoxin contamination. Food that is very contaminated with Aflatoxin can be dangerous, especially to young children. Contaminated maize has a yellowish green powder on the unshelled grains and even on shelled grains. Contaminated loose grains can also be blackish brown, although this is not an obvious sign.


The moulds can infect maize at any stage, from the field to the stores. The poison develops on maize when harvested wet or stored in damp conditions. The poison can also be spread by insects and rodents.
Although you can see the mould, the poison it makes has no special smell or colour. You cannot see it. The poison is not destroyed by cooking or grinding the contaminated maize. Animals that eat contaminated grains can become sick and can pass the poison on to people through products such as milk, eggs and meat.


  • After drying your maize to a moisture content of 13%, you may treat each bag of maize with 20 g of either Actellic Super or skana to prevent insect attack. Dust the granary and the sacks too with the same, following the instructions on the package.
  • Harvest the maize soon after ripening and when all the leaves are dry and the cob turns down. At this stage, the maize is dry and ready for shelling.
  • Maize varieties that do not open up when they are mature protect the grain better from the mould. Some closed varieties are 614 and 625. Open varieties include varieties 512 and 513.
  • Burn the affected grains. Do not feed them to animals.
  • Keep maize in dry, well ventilated stores. The best type of store is dry, rodent-proof and well-ventilated. It can be made of sticks, stones, mud or metal.

When using a pesticide, always wear protective clothing and follow the instructions on the product label, such as dosage, timing of application, and pre-harvest interval.

The recommendations in this factsheet are relevant to: Ghana, Kenya

Authors: Lucy W. Karanja
tel: +254 20 7224450 email:
©CAB International. Published under a CC-BY-SA 4.0 licence.

Plantwise Factsheets Library app

Get all of the factsheets and pest management decision guides from this website in an offline format via the Plantwise Factsheets Library app.