Kenya approves Kichawi Kill to combat Striga weed

Kenya has become the first country in the world to commercialise a weed technology, kichawi kill, to combat the Striga weed, alo referred to as kayongo or witchweed.

The witchweed is one of the worst threats to food security in sub-Saharan Africa.

Striga is a destructive parasitic weed that can cause up to 100% yield loss. It attacks the roots of staple crops such as maize, sorghum, millet, cowpea and upland rice.

It affects about 50 million hectares of African croplands, causing $9 billion in crop loss annually.  In addition, approximately 40 million farms and 300 million people across sub-Saharan Africa are affected.

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In the Western region alone, Striga has infested over 217,000ha of cropland, resulting in maize yield losses of up to 182,227 tonnes per year valued at $53 million.

Research shows over 70% of maize smallholder farmers in Kenya are women.

Although there are Striga-management technologies that exist, they have not been widely adopted by farmers due to mismatches between technology and socio-economic conditions.

Farmers and consumers are concerned about the potential poisoning of food and the environment arising from chemicals currently used to manage pests.

At the same time, weeds are increasingly becoming resistant to herbicides, which is also a global concern. 

Striga attacks the roots of the crop within 48 hours of planting, which means by the time weeding is done whether by hand or by using chemical herbicides, it is too late to reverse the damage.

Chemical coated hybrid maize seeds have not been proven safe and effective on striga control at the farm level.

Striga-tolerant crop cultivars, push-pull technology, and soil fertility improvement can boost crop yields but do not address the soil’s striga seed bank. Moreover, current costs of managing the pests often exceed the farmers’ economic means.

The Pest Control Products Board of Kenya last week registered the bio-herbicide with the Kenya Agricultural and Livestock Research Organization (KALRO).

The commercialization of Kichawi Kill follows decade-long collaborative research between KALRO and Montana State University that started in 2008. The bio-herbicide research focused on striga.

The research team also developed a unique distribution system that involved growing the selected fungal strains on toothpicks.

The trials showed 42-56% increase in crop yield, with similar results showing in the regulatory trials. While there have been other attempts at biological control of weeds, this is the first bio-herbicide to control striga in the world to be commercialized.

“Now that this biocontrol product is fully approved for use, we expect that its rapid adoption will help us to reduce the negative impact of striga and improve food security,” said KALRO director general Dr Eliud Kireger.

KALRO pathologist Sila Nzioki is continuing to work on the technology, including alternative application methods of the inoculum, and trials of striga in sorghum. He is also part of the team training international scientists from research organizations in 12 other countries to adopt Kenya’s model to identify their own locally-sourced fungal strains and to expedite regulatory processes.