Annual Report 2018 | Transforming cassava production in Africa through sustainable weed management technologies
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Transforming cassava production in Africa through sustainable weed management technologies

Transforming cassava production in Africa through sustainable weed management technologies

Transforming cassava production in Africa through sustainable weed management technologies

Kenton Dashiell, Alfred Dixon, Friday Ekeleme, Stefan Hauser, and Godwin Atser

One of the major constraints to cassava cultivaton in Africa is weed infestation. Weeds compete with cassava for water and nutrients. When left uncontrolled, weeds account for 40 to 80% of yield losses. In addition to yield losses, the presence and infestation of cassava farms by weeds heavily burden women, who carry out most of the weeding. In some cases, children are taken out of school and forced to support weeding, a practice that compromises their education and future development in general.

It is against this backdrop that the Cassava Weed Management Project (CWMP) was conceived in 2013 and launched in 2014 to address the research question of weeds in cassava farming systems. The research team worked on five broad areas:

  1. Agronomy – Attention was focused on the measures farmers can easily change to reduce weed infestation by appropriate tillage, variety, planting density, fertilizer, and intercropping. This component also investigated the use of mechanical and motorized weeders in cassava.
  2. Herbicides – More than 40 herbicides were screened to identify the efficient, safe, and environmentally friendly ones for application in cassava farming systems.
  3. Integration of best weed control options – Here attention was focused on identifying best agronomic factors already investigated and integrating them with best performing herbicides.

The last two components were taken to the dissemination stage by implementing the best weed control approaches in farmers’ fields to create awareness and impact at farm level.

On-station and on-farm trials were conducted in 2014 to 2016 to identify the best agronomic factors and herbicides that can effectively control weeds in cassava. By 2017 and 2018, the best agronomic factors and herbicides were packaged as the ‘Six Steps to Cassava Weed Management tool’ and advanced to farmers through on-farm demonstrations in four states of Nigeria: Abia, Benue, Ogun, and Oyo. These states represent three agroecologies: Humid Forest (Abia and Ogun), Guinea Savanna (Benue), and Derived Savanna (Oyo) noted for cassava production in Nigeria.

Transforming cassava production in Africa through sustainable weed management technologies

Over the last five years, the Project has identified preemergence herbicides that can be applied at the time of planting to inhibit weed germination in more than 100 trials. The use of these products combined with best agronomic measures such as improved varieties, plant density of 12,500 stands per hectare, combined with ridge-tillage and fertilizer application resulted in average yields that were 50% higher than those from hand weeding. When compared to national average yields of about 9 t/ha, cassava roots harvested from demo plots were more than double (20 t/ha and above). These remarkable results demonstrated the potential impact that the project could have on Nigeria’s cassava industry if farmers switch over to using the recommendations of the project as reflected in the ‘Six Steps to Cassava Weed Management’ toolkit. An economic analysis showed that farmers using the toolkit had 83% higher profit than those not using the toolkit.

Dissemination of results to farmers  

One unique feature of the Project was its emphasis ab initio of impact on farmers’ fields. Consequently, activities in years 2017 and 2018 focused more on dissemination of results using a multi-stakeholder approach involving training of extension service providers and spray service providers combined with digital approaches—primarily the use of television, radio, and mobile phones (WhatsApp and SMS). The Project collaborated with the private sector (chemical companies), development partners such as GIZ, Catholic Relief Services, Justice Development and Peace Movement in Oyo, KOLPING in Abia; and government agencies at federal, state, and local levels.

This approach reached more than 72,000 persons through training and farmer-to-farmer diffusion; 127,000 print materials were distributed to farmers; 222,000 were reached through social media platforms such as Facebook, LinkedIn, websites and Twitter; radio jingles were aired through local radio stations to a listening audience of 2.9 million persons. Furthermore, a documentary on the ‘Six Steps to Cassava Weed Management’ was televised on national TV in Nigeria with over 20 million viewership.

Looking ahead

Based on the implementation and progress made in the last five years, the CWMP has received a two-year extension within the framework of the African Cassava Agronomy Initiative (ACAI).

The two-year grant seeks to mainstream the CWMP data into ACAI with the goal to extend weed control research to Tanzania, the deregistration of Paraquat and piloting of digital extension approaches, that would see the expansion of the ‘Six Steps to Cassava Weed Management’ toolkit across the entire cassava growing area in Nigeria.

These new tasks will leverage on partnerships already created by the Partnerships for Delivery Directorate at IITA and harness existing relationships with chemical companies and agro-dealers.

There will also be more intensification on the use of digital tools such as the interactive voice response (IVR) that offers farmers especially women access to improved technologies via mobile phones.