When farmer John Indimuli noticed his half-acre farm producing significantly less maize, he became concerned.
Despite switching to sweet potatoes and other crops, his yields continued to decline.
Once, his farm produced eight bags of maize; now, he struggles to harvest even three.
“The production I had been getting here was more than eight bags. But right now, I can hardly get up to three bags. Even if you try to interchange the type of crop from maize and go to either sweet potatoes, it is still the same,” says Indimuli.
The culprit is visible among the crops – a parasitic weed known as striga, or witchweed.
The purple-flowered plant clings to the roots of maize and other staple crops, draining them of essential nutrients and water.
Indimuli has tried uprooting it by hand, but it keeps returning.
“This weed is just like the monster you try to kill but it can never be killed. The more you try to kill it, the more you create the problem. So the more you try to uproot this weed, the more it multiplies,” he says.
Striga is a major threat to food security in Western Kenya, an area with the potential to be the country’s breadbasket.
According to Michael Njagi, Productivity and Climate Resilience Officer at the World Food Programme (WFP), striga affects approximately 320,000 hectares in Kenya and 1.4 million hectares across East Africa, causing losses of up to 10% in crop yields.
“A farmer can lose up to a hundred percent of their crop when striga attacks,” warns Njagi.
Around 30-40 million people in sub-Saharan Africa are affected by the weed, with losses amounting to nearly $7 billion annually according to the WFP.
Losses caused by striga amount to nearly $7 billion annually, negatively impacting the livelihoods of more than 100 million people across the continent.
Striga is a significant barrier to food security and a threat to farmers’ investments, as it can lead to a total crop loss of up to 100 percent.
To combat the problem, farmers are increasingly turning to Kichawi Kill, a fungal bioherbicide developed by the Kenya-based social enterprise The Toothpick Company.
Unlike chemical herbicides, which can lead to resistance and environmental contamination, this bioherbicide uses a naturally occurring fungus to attack striga’s root system, preventing it from absorbing water and nutrients.
“Kichawi Kill is a bioherbicide made of a fungus, and this fungus attaches to striga. Once it does, it clogs up the root system and hinders striga from retrieving nutrients or water, making it wilt and die,” says Loise Kioko, a research scientist at The Toothpick Company.
Farmers using Kichawi Kill reportedly seen improvements in their yields.
The bioherbicide is preferred because, unlike chemical herbicides, it does not harm the environment, other crops and animals, or soil health.
“Unlike chemicals, which can have long-term effects on the soil and lead to herbicide resistance, this method is sustainable. It works with nature, not against it. Farmers can safely use it over multiple seasons without worrying about degrading their land or harming beneficial organisms,” Kioko says.
Farmer Lawrence Mukhabana, initially mistook striga’s flowers for decorative plants.
However, he soon realised the weed was stunting his maize crops despite his use of fertiliser.
“In 2023, during the long rainy season, the use of the bioherbicide increased my yield from 18 bags in 2022 to 22 bags, marking a rise of four bags,” Mukhabana says.
The WFP and the Farm to Market Alliance have partnered with The Toothpick Company to scale up adoption of Kichawi Kill. Demonstration plots have been set up across Western Kenya to train farmers on the bioherbicide’s application.
So far, more than 12,000 farmers have been reached, with 1,500 acres treated. The goal is to introduce the bioherbicide to 110,000 smallholder farmers in Western Kenya by 2025, with expansion plans targeting Uganda, Ethiopia, and Cameroon.
Striga infestation is most severe in countries like Sudan and Nigeria, where eight million hectares of land are affected – the highest in Africa. Across the continent, 25 countries are battling striga, which remains a serious threat to food security.
According to Kioko, the bioherbicide, which costs around USD 15 per acre, has shown potential to boost yields of staple crops like maize by up to 60 percent.
Since its inception in 2017, The Toothpick Company has treated over 10,000 acres of farmland in Kenya. Initially, adoption was slow due to the short shelf life of the bioherbicide, which was originally distributed as cooked rice.
However, a switch to a powder formulation in 2023 allowed for the treatment of 7,500 acres in a single season, paving the way for further expansion.
But climate change presents an ongoing challenge. Extreme weather patterns can influence striga’s dormancy, causing it to spread rapidly under favourable conditions.
Farmers are urged to adopt sustainable, biological solutions like Kichawi Kill to protect their livelihoods and mitigate the devastating effects of the weed.
