Harvesting maize early reduces loss

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Harvesting seasons usually pose a big challenge to farmers who do not plan well in advance. One of the major hurdles may be insufficient timing and lack of resources, especially labour. As a result, a lot of time is wasted as farmers look for money to pay for harvesting.

Some farmers wait until the school holidays to start harvesting when they get free labour from their school going children. When harvesting is done late, a lot of maize rots in the shamba, resulting in huge losses to farmers. Ideally, maize that is planted from mid March to end of April, would be ready for harvest in October.

Excess moisture causes rotting

This means that by September, most of the maize has reached maturity and needs to be cut and staked in readiness for harvesting. Experts advise that as soon as the silk at the tip of the maize cob (ear) turns black, the maize is ready for cutting and staking in readiness for harvest. If the maize stays longer than this period, chances are that a lot of it will start rotting. The short rains usually begin in October. Any maize that is not harvested during this period is often exposed to excess moisture. This encourages rotting and the development of mycotoxins which pose danger to humans and animals.

Proper drying before storage

After harvesting, the next big challenge is storage. Maize meant for storage should be properly dried. It should have a moisture content of about 13.5 per cent. Any moisture content above this percentage exposes maize to development of mycotoxins.


According to the UN World Health Organization (WHO) reports, billions of people in Africa and the rest of the developing world are exposed to aflatoxin poisoning. Aflatoxins cannot be seen with the naked eye. In most cases, infected maize looks normal. Aflatoxins can develop in maize when it is still growing in the shamba. This happens mainly when maize is harvested late due to high accumulation of moisture. Damage through broken grains and holes drilled by weevils and stem borers allow the fungus to invade the maize grain in the field and in the stores.

The danger of aflatoxin in maize

After harvest, most farmers sort rotten maize and set it aside for feeding livestock mainly cattle, sheep, goats, pigs and even poultry. What they may not know is that any rotten maize has a high level of mycotoxins that are harmful to people and animals. Mycotoxins are a group of naturally occurring chemicals produced by certain moulds (a type of fungi) which grow on cereals when they are exposed to warm moist conditions.

Mycotoxins can grow on variety of crops and foodstuffs including cereals, nuts, spices, dried fruits etc. Mycotoxins that are found in food are called aflatoxins (B1, B2, G1, G2 and M1). Mycotoxins can cause liver cancer, kidney damage, problems with digestion, reproductive disorder and suppression of the immune system in humans and even animals. Aflatoxins can cause immediate death in chickens and pigs.

Most feed manufacturers in Kenya rely on rotten maize to make animal feeds but they add toxin binders. Binders are compounds that attach themselves to the mycotoxins and prevent them from getting into blood stream through the animal’s stomach walls. Some of the manufacturers may not use the binders in the right way and these may affect animals and even people who consume milk, meat, eggs and other products from the affected animals.

>>Share your experiences with TOF and fellow farmers. Send email to [email protected]

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