Maize crop is a staple food in SSA where 95% of the maize produced constitutes a major part of the daily diet (Høgh-Jensen et al., 2007). Likewise, maize is the major cereal consumed and marketed after sorghum and millet in Nigeria (FAO, 2014). In a country like Nigeria, with the majority of its population engaged in farming and residing in rural areas, cereal productivity and food security are interrelated. Consequently, factors that affect cereal production can also impact on food security, as the majority of the poor population are directly dependent on cereals, which is relatively low-priced when compared to other forms of diet (FAO, 2014). Nevertheless, despite the potential for increased productivity, maize production faces many challenges, including low and erratic rainfall, poor soil fertility, drought, Striga, and long dry spells (Tambo & Abdoulaye,
13 This chapter gave rise to the following paper: M.B. Hassan, L.J.S. Baiyegunhi & G.F. Ortmann (under review). Striga management through herbicide resistant maize and its contribution to farm productivity in northern Nigeria. Submitted to Agricultural Systems.
2012). For the past decades, the IITA, in collaboration with CIMMYT and National Research Institutes, developed some early-maturing maize, and STR technologies that meet the requirement of small-scale farmers were disseminated in northern Nigeria and the West Africa savannah at large.
Maize is highly susceptible to Striga, which causes much damage to host crops across the savanna regions of Africa (AATF, 2006). Striga has invaded about 2.4 million ha of land under maize cropland, wreaking annual grain losses of about 1.6 million tons with an estimated value of US$383 million (Table 9.1). Striga infestation in Nigeria is most severe in the northern part, which covers about 835,000 ha, or arable land with an estimated loss of about 505,308 tons of maize, valued at US$205,660,000 million per annum. Fields in Nigeria affected by Striga, account for about 34% of land infested in Africa (Table 9.1).
Table 9.1: Striga-distribution yield and economic loss in Africa’s maize cropland for selected countries
Area Coverage
x1000 ha
Maize grain loss tons per year
Economic loss US$ per year
Sub-Saharan Africa (SSA) 2,363 1,623,838 383,290,000.00
Southern Africa 589 372,802 69,708,000.00
Malawi 291 208,221 27,900,000.00
West Africa 1,243 790,084 250,095,000.00
Nigeria 835 505,308 205,660,000.00
East Africa 531 460,953 68,487,000.00
Kenya 217 184,227 28,610,000.00
Source: Woomer and Savala (2007)
Striga decreases maize productivity by 20%-100%, at times leaving farmers with little or no grain at harvest. Maize losses in Nigeria from Striga alone account for about 100% of its deficit.
However, the majority of victims are the millions of small-scale farmers who see their crops wrecked year in year out, unable to produce enough food to feed their families or make some visible progress in their livelihood. The majority of farming households, particularly cereal growers, have developed a defeatist outlook to Striga, admitting that it has become part of them, and expected to die with Striga in their fields (Woomer & Savala, 2007). According to AATF (2008a) and Manyong (2008), an estimate of the area affected by Striga spp. in the world is
approximately 44 million hectares of arable land, affecting the livelihoods of more than 100 million smallholder farmers.
The farming community, particularly maize growers, responded to the Striga threat in numerous ways. They identified landraces that showed some Striga resistance, and these were later improved through traditional maize breeding, resulting in STR maize varieties. Another new method to manage Striga is through the planting of vigorous plants which antagonises Striga. Studies have identified legumes (cowpea, soya bean, pigeon pea, groundnuts, chickpea and desmodium) that provoke Striga and thereby induce it to germinate abortively. This is achieved through a process called push-pull (Khan et al., 2006a). Legumes such as soya bean and groundnut were also shown to asphyxiate Striga and induce what is known as suicidal germination, which is achieved either through maize rotation with legumes or through intercropping (Carsky, Singh & Ndikawa, 1994;
Ellis-Jones et al., 2004; Woomer et al., 2005). A herbicide called Imazapyr, which kills Striga plants while being harmless to maize crops, was also identified (Odhiambo & Ransom, 1993).
Mainly commercial farmers used these technologies.
These new technologies worked, even though a part of the land from that used for the main food crop production needed to be sacrificed. Alternatively, it is presumed that farmers gain an advanced understanding of the complex ecology associated with Striga (Woomer & Savala, 2007).
IRM is achieved through the application of a little quantity of Imazapyr to maize seeds, which is believed to offers many weeks of protection from the action of Striga (Kanampiu et al., 2002). The Imazapyr technology is a result of many years of research and development by different organisations. Maize resistance to the herbicide Imazapyr was initially developed by American Cyanamid, a US-based company.
9.2.1 Imazapyr-resistant maize (IRM) trials and dissemination in Africa
In SSA, the first IRM was produced at CIMMYT-Zimbabwe then followed by CIMMYT-Kenya through collaboration with the Agricultural Research Institute (KARI) of Kenya. KARI multiplied maize seeds for Imazapyr testing and breeding. According to Mignouna et al. (2011a), “the practicality of covering IRM seeds with the imazapyr herbicide was first demonstrated through the collaborative research at the KARI-Kibos station outside of Kisumu (Kanampiu et al., 2002). In 2004, the IRM was then deployed to farmers for on-farm testing on a large scale, and it was funded
by AATF especially the multiplication of Ua Kayongo by Western Seed Company. A drive of pre- release testing of IRM was launched by AATF (Otieno et al., 2005), with over 13,000 smallholder farmers and when compared to other Striga management technologies across 120 localities in West Kenya (Woomer et al., 2005) with a favorable results. Compared to the recommended commercial hybrid (H513), Ua Kayongo improved maize yields by 1,022 kg ha-1, increased farmer’s net return by $143 ha-1 (+63%) and reduced Striga expression by 81%. (AATF, 2005).”
The success recorded in Kenya triggered the dissemination of IRM maize to other parts of Africa, with the collaboration of many institutions, to reduce Striga constraints to maize production, also in northern Nigeria. The ISMA project was funded by the Bill & Melinda Gates Foundation. IITA collaborated with the IAR of ABU and other stakeholders to disseminate the improved agricultural Striga management technologies, among which was IRM, to the two states. This paper collected information on socioeconomic characteristics of maize farmers in northern Nigeria that attended the ISMA field days and when compared the productivity of IRM technology with the farmer varieties as control methods.
The development and advancement of IRM can improve the productivity and nutrition of smallholder farmers, particularly women and children in communities where maize form their staple food. Maize is currently the major source of raw material in feed production by livestock industries, particularly for poultry. Therefore, maize has a great potential to augment food insecurity through increased productivity and sustainability of the crop and livestock production system (Alene et al., 2006).
The study reports on two sets of on-farm trials, conducted across the two states, to show the contributions of two hybrid varieties (IRMs: IRM1 and IRM2) to maize productivity and maize farming households income. The study also reported socioeconomic characteristics of farmers who attended farmers’ field days. In the remaining parts of the chapter, section 3 discusses the materials and methods, section 4 presents the results and discussion, and lastly, section 5 concludes with a summary and some recommendations that can contribute to the increased use of hybrid IRM technology.