Fungal growth and aflatoxin contamination in crops occur due to several factors: some are environmental in nature while others are crop management related. Farmers have minimal control on environmental factors; however, they can improve agricultural practices used in crop production to reduce fungal infection, growth and aflatoxin production.

2.2.1. Crop management practices that reduce infection in the field

These approaches target minimization of pre-harvest infection by fungi. They aim at providing crops with the best possible growth environment so as to avoid infestation by insects, drought and subsequently infection by fungi. 

• Early planting: Early planting helps plants to escape end of season drought that in general predisposes pods to cracking and entry by A. flavus.
• Maintaining field hygiene: Timely weeding helps to retain soil moisture needed for proper plant growth and avoidance of dry conditions that predisposes developing pods to cracking. Termite control is also very important to prevent damage to developing pods, especially as the crop matures.
• Harvesting of water in the field: Drought conditions while the crop is growing in the field is a prerequisite to fungal contamination and subsequent aflatoxin contamination. Farmers should ensure that they retain moisture in their fields. The use of tied ridges (box ridges) can improve water penetration into the soils, thereby reducing exposure of the developing crop to A. flavus infestation. Box ridges should be put in place early in the cropping season to capture enough rainwater and reduce effects of end-of-season drought. Mulching also helps to retain water in the field.
• Soil amendments: Application of lime to the crop supports development of strong shells (pod resistance). Strong shells provide the first line of defence against pest and fungal attack.

2.2.2. Crop management practices that reduce infection during harvesting

These are management practices that reduce contamination of pods and grain by reducing and/or avoiding exposure of grain to fungi.

• Harvesting at the right stage: Premature kernels have high moisture content and support fungal infection and growth, and aflatoxin contamination. Therefore, harvesting at the right time when the crop is mature will minimize the exposure of the crop to extreme heat, sudden rain or drought, which also influence infection.
• Avoiding injuries to pods: Care should be taken when using hand hoes to avoid injury to the pods. Proper harvesting of groundnuts ensures that the hoe is focused at the plant’s rooting zone to avoid damaging pods or kernels.
• Removal of soil: It is important to remove all the soil attached to the pods during harvesting to avoid carrying the fungus into stores and processing facilities.

2.2.3. Crop management practices that reduce contamination after harvest

Postharvest handling of crops is another major point of contamination that if well managed will minimize infection of harvests by fungus and minimize aflatoxin contamination. Management practices may be implemented at two levels.

At the household level

• Proper drying: Drying on roof or on soil leads to the absorption of moisture and supports fungal growth that leads to aflatoxin contamination. The use of Mandela Corks (ventilated stacking) is one of the best methods for curing the groundnuts and is specifically preferred for its ability to minimize the direct exposure of groundnuts to the sun. Mandela Corks should be stacked on a raised platform, leaving a hollow space in the middle to allow air circulation inside the structure.
• Proper shelling: Sprinkling water on pods to shell the groundnut leads to fungal accumulation and aflatoxin production. It is therefore always better to avoid wetting pods during shelling. The use of mechanical shellers can also reduce labour cost.
• Grading and sorting: Fungi readily invade kernels with cracked or damaged pods or seed coats. Removal of such damaged, discoloured, small and shrivelled pods reduces the amounts of infected produce in the lot.
• Proper storage: Entry of insects and moisture into storage lots allows the entry of fungus and eventually aflatoxin contamination. Grains should be stored in a dry and secure place where the entry of insects and moisture is not possible.

Tips to minimize storage contamination

• Store grains in cool dry conditions.4
• Stack gunny bags on wooden planks to avoid dampness.
• Ensure the storage has good roofing to prevent groundnuts from getting wet if it rains. Ensure the storage rooms are hygienic to avoid the contamination from the previous lot.
• Using good packaging materials for storage, gunny bags are most appropriate for groundnuts. If nylon bags are used additional perforations need to be made to facilitate air circulation or store in them only for a short time.
• Ensure groundnuts are not exposed to pest and rodents to minimize damage.
• Ensure good aeration in the storage room.