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Pernicious Weed Meets its Match

CIMMYT E-News, vol 2 no. 7, July 2005
striga1In a country where each person consumes at least 100 kilograms of maize a year, a new, easy-to-use, affordable practice that could raise the crop’s production by 200,000 tons is, naturally, greeted with much celebration in Kenya.

Such was the mood at Kisumu, Kenya, during the 5 July launch of the Clearfield® technology for Striga weed control. “This is good news for farmers, and good news for the government,” stated the chief guest, Romano Kiome, director of the Kenya Agricultural Research Institute (KARI). If widely adopted, according to Kiome, the technology could “…lift poor farmers from subsistence to income generation, poverty to wealth, and food insecurity to security.”

A highly invasive parasite, Striga infests 400,000 hectares of Kenya’s farmland. Striga sprouts fasten directly to roots of maize seedlings, sucking away nutrients and 50 to 100% of yields by harvest time. The weed overruns 40% of the arable land in Africa’s savannahs, threatening the livelihoods of more than 100 million people who depend on cereal crops for food and income. Kenyan maize farmers lose at least US$ 50 million annually in grain to Striga.

Taking advantage of a natural variation in maize, for nine years CIMMYT and partners have conventionally bred varieties that yield well under tropical conditions and withstand imidazolinone, an active ingredient in several herbicides and the BASF product, Strigaway®. This imidazolinone-resistant (IR) maize is the starting point for an elegant control method, as CIMMYT agronomist Fred Kanampiu explains: “The IR maize seed is coated with a low dose of the herbicide, which kills Striga as it germinates, allowing the maize to grow clear of the weed.” Besides producing healthy maize plants, over several years the practice helps clear fields of residual Striga seed—a boon to farmers, given that a single Striga plant produces up to 50,000 tiny seeds that can remain viable for 20 years or more.


Four new maize hybrids have been released for marketing in Kenya under the common name Ua Kayongo (literally “kill Striga”) H1–4, and farmers are enthusiastic, as their statements in the Nairobi Daily Nation show: “I have already seen major changes in my farm compared to my neighbors’, whose parcels remain covered with the purple flowers of the parasitic weed,” says Zedekiah Onyango of Baridi farm in Nyahera. “My maize yield is many times higher since I started using IR maize, and I look forward to even higher yields.” Farmers are also urging the government to promote the technology to arrest the perennial food shortages caused by Striga. “I believe it would be much cheaper for the government to invest money in the technology, so that this menace is cleared once and for all, and the production of various cereals is restored,” says Beatrice Ayoo, another small-scale farmer who is interested in the new Clearfield® practice.

The technology was developed through global cooperation involving CIMMYT; KARI; the Weizmann Institute of Science, Israel; BASF; private seed companies; and the Rockefeller Foundation; among others. Peter Matlon, director for the Africa Regional Program, the Rockefeller Foundation, was at the launch, and called the cross-sectoral collaboration “a classic example of partnership.” The Clearfield® control package will be released soon in Tanzania, Uganda and, eventually, 16 other countries of sub-Saharan Africa, in a process spearheaded by the African Agricultural Technology Foundation (AATF) with DFID support.

For more information, contact Fred Kanampiu (f.kanampiu@cgiar.org).