New edition of popular field guide on maize diseases

December, 2004

Reducing Damage to Grain Stores of the Poor

Saving grain from hungry pests can significantly improve the food security and livelihoods of farm households in the developing world’s poorest areas.

Even if poor farmers have a good maize harvest, many who live in humid environments and do not have effective storage containers face significant grain losses in the following months. Grain can suffer 80% damage and 20% weight loss within six months after harvest in Mexico’s harsh tropical environments, where grain-damaging insects thrive, according to CIMMYT entomologist David Bergvinson. “Two major pests in Africa—maize weevil and larger grain borer—can consume as much as 15% of a harvest in a few months,” says Bergvinson. Working on reducing storage losses is one way that he and other CIMMYT scientists target impoverished areas, increasing food security and allowing farmers to enter grain markets when prices are favorable.

Participatory Breeding to Foil Weevils

There are several ways to lessen grain damage. Farmers can remove infested grain and thoroughly clean storage facilities to eliminate insects before storing new grain. Improved grain storage technologies, such as silos, also help. Finally, scientists can breed maize to be more insect resistant with tighter husks or harder kernels. “With resistance as an inherent part of seed, farmers can cut back on the use of noxious pesticides,” says Bergvinson.

Working to breed hardier maize, Bergvinson crossed farmers’ varieties in Mexico with insect-resistant and drought-tolerant CIMMYT varieties and returned the seed to farmers for planting in mid-2004. Researchers also planted these crosses on farms near CIMMYT research stations to evaluate their performance, to make controlled pollinations, and to compare farmers’ selections with their own. “Our ultimate goal is to increase the genetic diversity of landraces with resistance to production constraints identified by farmers,” says Bergvinson. Farmers most often asked for drought and weevil resistance to be added to their landraces

Targeting Peaks of Poverty

Bergvinson and his associates are working with 54 farmer varieties for lowland tropical areas of Mexico and 36 for higher altitudes (1,200-1,800 meters above sea level). It is in many of these hill zones where poverty and maize-bean subsistence farming go hand in hand. The methods applied could have relevance for smallholder maize farmers in other parts of Latin America and in Africa.

In preparation for extending their efforts to reach more of the poor, the researchers have also sampled farmer varieties in eight Mexican locations identified in a recent CIMMYT study (see Maps Unearth New Insights for Research to Help the Poor) as having a high concentration of the poor. “We’re working with farmers in these areas to improve their varieties for traits they identify, such as resistance to storage pests and, in hill zones, stronger roots and stems so that plants don’t fall over in strong winds,” Bergvinson says. The researchers are also taking care to maintain other traits that farmers value. One example in lowland areas is the long husks that farmers remove and sell as wrapping for the popular Mexican dish known as “tamales.” In some communities, husks for this purpose are worth more than the grain (see Rural Mexico and Free Trade: Coping with a Landscape of Change).

Global Science to Protect Grain

Bergvinson belongs to a worldwide community of researchers applying science at all levels to develop pest-resistant maize. “A small but noticeable renaissance in the use of resistant varieties to minimize storage losses is taking place worldwide, especially for ecologies where storage infrastructure doesn’t exist,” says Bergvinson. He says researchers have made significant progress in understanding the biochemical, biophysical, and genetic bases for resistance, among other things to ensure the traits satisfy consumer demands. Such traits are being “mapped” using DNA technology to confirm their role in resistance and to identify the genes involved. “The real potential of this technology will be felt in developing countries,” Bergvinson explains. “The resistance is packaged in the seed and designed to ensure that farmers have the option to recycle seed, a practice common to small-scale farmers.”

For more information: d.bergvinson@cgiar.org