|
Kenyan farmers are releasing a big sigh of relief following a breakthrough by scientists in controlling the Striga weed (Striga hermonthica), also known as the witch-weed. Striga is a parasitic weed that destroys cereal crops, especially maize, a staple food in Kenya, causing food insecurity in thousands of households.
Combating the Threat
The weed is a serious constraint in the production of maize, rice, sorghum, sugarcane, Napier grass, and millet, not only in Kenya, but also in the whole of sub-Saharan Africa. The weed, which was first noticed in Kenya in 1936, has invaded about 180,000 acres (72,840 hectares) of land, resulting in estimated losses of US$53 million.
To reverse the trend, the Kenya Agricultural Research Institute (KARI), in collaboration with the African Agricultural Technology Foundation (AATF), and the International Maize and Wheat Improvement Centre (CIMMIYT), has developed a new maize variety known as Clearfield IR-Maize that is resistant to the weed.
Elusive Enemy
According to the AATF, agriculturalists in the country had previously assumed that improved soil fertility and a combination of other methods such as hand weeding and burning could control the weed, but its infestation continued to be severe. The foundation's mission is to link smallholder farmers with poor resources in sub-Saharan Africa to potential technological solutions.
Speaking to the press during the launch of the new maize variety, KARI director Dr. Romano Kiome said that "controlling the weed had been made difficult by its rather complex lifecycle."
Striga produces many tiny seeds that fall on the soil and are subsequently incorporated into it during tillage. These seeds can remain dormant for up to 15 years until they are stimulated to germinate by biochemical signals in the host plant.
The germinating seeds penetrate the host root and feed on it for several weeks by removing water, minerals, and photosynthates (food products created by photosynthesis) while living underground. During this time, the Striga produces toxic chemicals that stunt and discolor the host plant.
The weeds eventually emerge from the soil producing luxuriant green stems and narrow leaves that can grow to a height of 50-100 centimeters (20-39 inches). The weed later produces small purple flowers that form capsules containing more seeds. When the host plant dies, so does the Striga. As this occurs, the capsules burst, releasing over 5,000 seeds. The cycle then repeats itself.
Given that the seeds are invisible to the naked eye, they are easily spread to new areas by humans and animals.
An Effective Method
|
| A pretty sight, but not appreciated by African farmers. |
AATF communications manager Nancy Muchiri said the IR maize, which farmers in Western Kenya refer to as ua Kayongo (meaning "Kill the Striga"), is a hybrid maize coated with a systemic herbicide (Imazapyr) that kills the germinating Striga as they attempt to infect the maize plant. She said that the technology, which was developed over a period of 8 years, was launched in mid-2005. "On-farm trials are going on in twelve districts, and we are unable to cope with the demand for seeds. Farmers get amazed when they witness a patch of land where previously nothing grew suddenly turning productive," she said.
Muchiri explained that the Clearfield IR-Maize was not a genetically engineered maize variety. "These seeds are conventionally bred and their difference with other hybrid seeds is their resistance to the Striga weed."
Apart from killing the Striga, the new maize variety is superior to other hybrid varieties grown in the area, as it yields 38 to 82 percent more than the traditional varieties, said Muchiri. Clearfield IR-Maize is planted and managed in the same way that farmers grow other maize varieties. While intercropping with legumes is allowed, farmers are warned against planting legumes with maize, as the herbicide may affect the legume seed. Farmers were instructed to wash their hands after handling the seeds as a safety precaution, said Muchiri. Farmers were also instructed to avoid handling other seeds before they wash off the herbicide as this may affect the germination of the handled crops.
Crossing Borders
AATF intends to take the technology to the rest of sub-Saharan Africa. Already the seeds of the new maize variety are under evaluation in Malawi, Zimbabwe, Ethiopia, Ghana, Benin, Senegal, Cameroon, and Sudan.
Striga infests an estimated 20-40 million hectares (49-100 million acres) of smallholder farmland in sub-Saharan Africa. AATF stated that the damage caused annually by Striga in sub-Saharan Africa was to the tune of US$1 billion, affecting the livelihoods of an estimated 100 million people in the region.
Faster Adoption
Muchiri disclosed that AATF has developed information materials to fight the Striga with the new maize variety and liaises with government extension officers and non-governmental organizations to reach out to farmers on their farms. Around 21,000 farmers have benefited from the demonstrations. "I planted the new maize variety on my two-acre farm in the last season, and in comparison to what I have been harvesting on the same farm, yields virtually doubled," said Charles Ofuko, a subsistence farmer in Busia District.
Despite impressive results, farmers were advised by extension officers to incorporate other methods of fighting Striga as well as using IR-Maize for better results. Although a few companies are already producing the new maize seeds, their production is expected to be fully commercialized by next year with a total of 12 tons of seeds to be made available for farmers to purchase.
Food Security
Muchiri said that the new method of fighting Striga would increase maize production in western Kenya by 61,920 metric tons, valued at US$53 million. Apart from the Striga-resistant maize project, AATF is working on 10 other projects to ensure that smallholder farmers in Africa can access technologies that will improve food security and reduce poverty. These projects include improving cassava production in smallholder farms, controlling locust and grasshopper populations, building sustainable seed systems, and increasing banana and plantain productivity and drought tolerance in cereals.
|
