Low cost and safe pest control for the storage of cowpea by small-scale farmers

Partners:
Ministry of Food and Agriculture, Northern Region, Ghana
Kawanda Agricultural Research Institute, Uganda
Matilong Mixed Youth Farming Organisation, Uganda
Serere Agricultural and Animal Production Research Institute, Uganda

Problem:
In the dry zones of sub-Saharan Africa cereals and legumes once harvested must be stored throughout the long dry season if food is to be available, or if households are to have the option of selling their grain.  Selling later in the dry season commands higher prices, due to relative scarcity.  However, small-scale farmers often find that the cowpea beans are severely damaged during storage by an insect pest, the cowpea or bruchid beetle, Callosobruchus maculatus.

The Solution: solar energy.
The output is a simple but effective solarisation technique, which harnesses the power of the sun to reduce pest damage on stored cowpea to acceptable levels.
In tropical regions, the sun is a powerful and reliable source of energy and simple technologies can make use of this free resource. Appropriate exposure of cowpeas to the sun can lead to a temperature rise sufficient to kill most if not all of the pests – eggs, larvae and adults – on and inside the grains.
Germination tests showed that grain stored for seed remains viable.

The technique in short:

• Dried cowpea grains are spread in a thin layer on a flat area of ground where sun exposure will be high for a whole day. The ground should be cleared of debris.
• To avoid contaminating the grains and to improve temperature retention, locally available (e.g. straw) mats are first arranged on the floor and covered with second-hand jute sacks.
• The layer of cowpea grains on the jute sacks should not be thicker than 2 or 3 cm (1 finger's joint when probing the grain).
• The spread cowpea grains are covered with a thin transparent polythene sheet, which is held in close contact to the grain with weights (stones etc).
• It is important to keep animals (goats, chicken etc) away from the cowpea during the treatment.
• Sacks or containers in which the cowpea is stored should be cleaned during exposure to the sun to avoid re-contamination.

Repeated monthly during the storage season, this treatment offers very good levels of protection for a limited initial investment.

The technique is described in detail and with graphical illustrations in two extension booklets prepared within the project, one for extensionists and one for farmers.