Kenya has taken lead in providing sorghum farmers with a technology-based solution to the Striga menace. In a media science café hosted by OFAB Kenya, Professor Steven Runo outlined how his research team at Kenyatta University is working with local farmers to develop a technology platform for the deployment of sorghum varieties with durable resistance to Striga.

Parasitic weed Striga is a huge constraint to the production of sorghum and other cereal crops. The parasite attaches to host crops and siphons nutrients leading to severe growth retardation and death of infected plants. Most cultivated cereals, including maize, millet, sorghum, and rice, are parasitized by at least one Striga species, leading to enormous economic losses. The Striga genus has over thirty species distributed over 50 countries in sub-Saharan Africa, causing an estimated 7 billion dollars worth of crop losses every year.

Striga control technologies include intercropping with non-hosts, weeding, and chemical control. However, these strategies are either inefficient or not adaptable to smallholder farming systems. The most efficient and cost-effective way to control Striga infestations would be to develop crops that are resistant to Striga. Overall, integrated control strategies that exploit natural resistance are universally recommended. However, to date, only a few resistant varieties are released and adopted by farmers and often the resistance is weak or rapidly overcome by the parasite.

Over the past few years, Prof. Runo’s research team has been exploring different methods of building Striga resistance in sorghum and other cereal crops that are key staples in Africa. The team is working with local farmers and extension officers to select – from a set of Striga-resistant varieties already tested under laboratory and field conditions, sorghum varieties with preferable traits. In this participatory variety selection process, farmers are able to grow sorghum varieties on their farms before making their selection. This has been particularly important in the identification of farmer-preferred, locally adapted sorghum varieties with improved potential to maintain resistance in farmers’ fields.

In addition, Prof. Runo’s team, in partnership with Corteva Agriscience, is using genome editing to develop Striga-resistant sorghum varieties. In this approach, the team has used CRISPR/Cas9 to knock out the low germination stimulant 1 (LGS1) gene, drastically reducing Striga germination stimulant activity. The genome-edited lines will be evaluated for resistance in the Striga high-burden region of Western Kenya.