Saving Seed in Senegal

Peanut seed loss to the peanut bruchid (Caryedon serratus) during storage is a major problem in Senegal, even where pesticides are used. To battle the problem, the On-farm Seed Production Project (OFSP) joined forces with the Peace Corps African Food Systems Initiative to find effective peanut seed storage methods and to promote their use through extension.

Storage Methods

Informal surveys revealed a variety of local strategies for protecting seed stocks. Some farmers shelled seeds before storage, some after. Some used sacks, others oil drums. Some treated the seed with methyl parathion, a highly toxic and widely banned insecticide; others added ash, sand, neem leaves, or nothing.

Several of these seed storage methods were tested under farmer conditions. Peace Corps volunteers conducted field trials in the departments of Nioro and Bignona at nine locations using 20 kg samples of peanuts in transparent plastic bags. Along with a control, the following treatments were applied:

Chemical. Actellic (2% primiphos methyl, considered safer than methyl parathion) was used at a rate of 50 g/100 kg of peanuts.

Wood ash. Wood ash was mixed with peanuts at a rate of 1:4. The sharp ash particles create an abrasive action, which can scratch the cuticle of the insect and cause death by dehydration or by loss of its ability to regulate body temperature. Ash can also block insect movement and may have a detrimental effect on egg development.

Sand. Sand was mixed with peanuts at a rate of 1:2. Like ash, sand has an abrasive effect and hinders insect movement. It also reduces the oxygen available to insects and draws moisture from the seeds. However, weight is a consideration, because sacks of seed become hard to move around.

Neem leaves. Dried, crushed neem leaves were mixed with peanuts at a rate of 1:4. It is well-known that neem leaves and seeds have insecticidal properties, mostly concentrated in the seeds. However, leaves were used because seeds are more difficult to process.

Early removal. Peanut bruchids attack while the crop is drying in the field. Locally, peanuts are left exposed and stacked in the field for two to four months after harvest. In an attempt to reduce initial infestation, volunteers removed the peanuts from the field two to four weeks after harvest when the crop had reached a safe moisture content of 10 percent. Some were treated with Actellic and others were not.

Traditional brick box. A clay and brick box was filled with peanuts treated with Actellic and sealed with clay. This treatment was based on a box design used in The Gambia.

Trial results indicate the chemical, sand, and ash treatments were all effective in minimizing peanut losses to the bruchid. That locally available sand and ash were as effective as the chemical insecticide is particularly encouraging. Neem leaves were not effective. Early and traditional removal treatments using Actellic were not significantly different. When neither was treated with insecticide, the early removal treatment had significantly better results. Results of the box treatment were inconclusive due to a termite attack and to problems with box construction

Extension

The Peace Corps volunteers and OFSP organized field days at each site. This gave farmers and extension agents the chance to present trial results to other farmers. Peanut samples were passed around, so the farmers could see the results of different treatments.

Farmers at the field days were surveyed about their current seed storage practices, and they expressed interest in conducting their own trials of the treatments presented. These surveys and discussions were the basis for determining follow-up activities. Further work is planned using sand and ash in traditional jute or burlap sacks instead of plastic, as well as improving the brick box design, storage in oil drums, etc. The following general extension package is being recommended for peanut seed storage:

  • early removal from the field

  • thorough cleaning and drying before storage

  • storage in clean bags off the floor

  • use sand or ash as a preferred treatment, insecticide if its efficacy can be guaranteed

  • maintain a clean and organized storage area

  • regular inspection of seed to detect storage problems.

    • For Publications:

    Steve Grant
    Winrock International
    Rt. 3
    Morrilton, Ark. 72110 USA

    For more information on OFSP:

    Tom Osborn
    OFSP s/c de PRITECH
    B.P. 3746
    Dakar, SENEGAL