Striga Management through Herbicide Resistance: A Public-Private Partnership in Action

Striga is an indigenous parasitic weed that attacks cereals and other crops in Africa. In maize croplands alone, Striga infests over 2.3 million ha resulting in 1.6 million tons of grain loss worth US $383 million annually. An innovative approach to controlling the parasite was to induce herbicide resistance in maize and to coat the seed with herbicide to provide chemical protection from infection. This breakthrough that was realized after 12 years of collaborative research and development by the International Maize and Wheat Centre (CIMMYT), the Kenya Agricultural Research Center (KARI) and the Weizmann Institute of Science in Israel, is now ready for deployment in Sub-Saharan Africa. This effort is most advanced in Kenya, where one variety of the Imazapyr-resistant (IR) maize hybrid aptly named Ua Kayongo (Striga Killer) was tested by over 13,000 households and registered for commercial release by Western Seed Company. Compared to a currently recommended commercial hybrid (H513), Ua Kayongo improved maize yields by 1,022 kg ha-1, reduced Striga expression by 81$143 ha-1 (+63%). This technology occupies a central role in the design of comprehensive Striga Eradication Initiatives in maize fields, but hindrance to achieving this goal has emerged from unlikely sources. Crop breeders committed to developing alternative, Striga-immune varieties self-indulgently dismiss IR maize as a technological dead-end single gene approach, while “green” interests unfairly label IR-maize a GMO. A public-private partnership has formed to deploy IR maize to needy African farmers. Differences in operational approaches are expected among these partners, given their underlying interests and organizational mandates, and it is important that these issues continue to be resolved in a manner that does not lose momentum or shift focus. Now that Striga has become a preventable disorder in maize fields, it is time to minimize the drama and direct all available resources toward assisting Striga’s victims in Africa.Africa, Herbicides, Maize, Striga, Agricultural and Food Policy, Community/Rural/Urban Development, Environmental Economics and Policy, Food Consumption/Nutrition/Food Safety, Food Security and Poverty, Health Economics and Policy, Land Economics/Use, Marketing, Productivity Analysis, Research and Development/Tech Change/Emerging Technologies,

Determining smallholder farmers’ preferences for Push-Pull technology dissemination pathways in western Kenya

The push-pull technology (PPT) has widely been disseminated to control stemborer (Chilo partellus and Busseola fusca) and Striga weeds (Striga hermonthica and Striga asiatica) in maize fields in Kenya. This study examined farmers’ preferences for various dissemination pathways in order to proffer better targeting of resources in an optimal dissemination strategy. The pathways considered were public meetings (barazas), radio, farmer field schools (FFS), field days (FD), farmer teachers (FT), the fellow farmers (FF) and print materials. Using a weighted score index and ordered probit regression, the different pathways were sequentially ranked as FD, FT, FFS, FF, print materials, Radio, and barazas. Marginal effects from ordered probit showed that farmers had the least preferences for baraza and radio pathways. The farmer categories with the highest preference for particular pathways were: less educated farmers for FD, farmers with small land sizes for FT, farmers belonging to groups for FFS, and young educated farmers for the print materials. This information is extremely important for targeting the different segments of farmers.Push-pull technology, Stemborer, Striga, Dissemination pathways, preference, Research and Development/Tech Change/Emerging Technologies,

An integrated molecular and conventional breeding scheme for enhancing genetic gain in maize in Africa

Open Access Journal; Published online: 06 Nov 2019Maize production in West and Central Africa (WCA) is constrained by a wide range of interacting stresses that keep productivity below potential yields. Among the many problems afflicting maize production in WCA, drought, foliar diseases, and parasitic weeds are the most critical. Several decades of efforts devoted to the genetic improvement of maize have resulted in remarkable genetic gain, leading to increased yields of maize on farmers’ fields. The revolution unfolding in the areas of genomics, bioinformatics, and phenomics is generating innovative tools, resources, and technologies for transforming crop breeding programs. It is envisaged that such tools will be integrated within maize breeding programs, thereby advancing these programs and addressing current and future challenges. Accordingly, the maize improvement program within International Institute of Tropical Agriculture (IITA) is undergoing a process of modernization through the introduction of innovative tools and new schemes that are expected to enhance genetic gains and impact on smallholder farmers in the region. Genomic tools enable genetic dissections of complex traits and promote an understanding of the physiological basis of key agronomic and nutritional quality traits. Marker-aided selection and genome-wide selection schemes are being implemented to accelerate genetic gain relating to yield, resilience, and nutritional quality. Therefore, strategies that effectively combine genotypic information with data from field phenotyping and laboratory-based analysis are currently being optimized. Molecular breeding, guided by methodically defined product profiles tailored to different agroecological zones and conditions of climate change, supported by state-of-the-art decision-making tools, is pivotal for the advancement of modern, genomics-aided maize improvement programs. Accelerated genetic gain, in turn, catalyzes a faster variety replacement rate. It is critical to forge and strengthen partnerships for enhancing the impacts of breeding products on farmers’ livelihood. IITA has well-established channels for delivering its research products/technologies to partner organizations for further testing, multiplication, and dissemination across various countries within the subregion. Capacity building of national agricultural research system (NARS) will facilitate the smooth transfer of technologies and best practices from IITA and its partners

Geographical distribution and aspects of the ecology of the hemiparasitic angiosperm Striga asiatica (L) Kuntze: A herbarium study

Striga asiatica (Scrophulariaceae) is an obligate root hemiparasite of mainly C-4 grasses (including cereals). It is the most widespread of the 42 Striga species occurring in many semi-tropical, semi-arid regions of mainly the Old World. Examination of herbaria specimens revealed that S. asiatica has a wider geographical distribution, is present at higher altitudes and occurs in a more diverse range of habitats than previously reported. The host range is also larger than previously reported and is likely to include a large number of C-3 plants. Morphology of examined specimens revealed variation in size and corolla colour suggesting the existence of ecotypes. Climate may exert a significant influence on the distribution of S. asiatica given the diversity of potential host plants and their distribution beyond the current recorded range of S. asiatica

Striga seed-germination activity of root exudates and compounds present in stems of Striga host and nonhost (trap crop) plants is reduced due to root colonization by arbuscular mycorrhizal fungi.

Root colonization by arbuscular mycorrhizal (AM) fungi reduces stimulation of seed germination of the plant parasite Striga (Orobanchaceae). This reduction can affect not only host plants for Striga, resulting in a lower parasite incidence, but also false hosts or trap crops, which induce suicidal Striga seed germination, thereby diminishing their effectiveness. In order to better understand these AM-induced effects, we tested the influence of root colonization by different AM fungi on the seed-germination activity of root exudates of the Striga hermonthica nonhost plants cowpea and cotton on S. hermonthica. We also tested the effect of AM fungi on the seed-germination activity of the Striga gesnerioides host plant cowpea on S. gesnerioides. Moreover, we studied whether mycorrhization affects the transport of seed-germination activity to above-ground plant parts. Mycorrhization not only resulted in a lower seed germination of S. gesnerioides in the presence of root exudates of the S. gesnerioides host cowpea but also seed germination of S. hermonthica was also lower in the presence of root exudates of the S. hermonthica nonhosts cowpea and cotton. Downregulation of the Striga seed-germination activity occurs not only in root exudates upon root colonization by different AM fungi but also in the compounds produced by stems. The lowered seed-germination activity does not appear to depend on the presence of seed germination inhibitors in the root exudates of mycorrhizal plants. The implication for Striga control in the field is discusse

Classification and influence of agricultural information on striga and stemborer control in Suba and Vihiga Districts, Kenya

This paper reports on findings of a study to examine the sources used by farmers in search of agricultural information on striga and/or stemborers control technologies and factors that influence acquisition of such information in Western Kenya region. A random sample of 476 households in Suba and Vihiga districts were interviewed and 15 information pathways were identified. Using principle component analysis (PCA) to derive few latent variables that encapsulate maximum variance in the pathways, two components (latent variables) proxying for ‘agricultural knowledge’ were extracted. Type I-knowledge (first component) loaded heavily with sources that had ‘group’ information searching. Type II-knowledge (second component) loaded heavily with sources requiring individual farmer search. Both types of knowledge positively and significantly influenced the likelihood of households using improved technology to control stemborer, while only Type-II knowledge and social economic factors were important in influencing the farmers’ likelihood of using an improved technology to control striga. This study shows that information is an important factor in the households’ likelihood of using improved technologies in the control of striga and stem borer in Vihiga and Suba, Kenya. Methods of individual interaction are important to striga control.Agricultural information, improved technology, striga, stemborers, control technologies, Kenya, Agricultural and Food Policy, Community/Rural/Urban Development, Demand and Price Analysis, Farm Management, Food Consumption/Nutrition/Food Safety, Food Security and Poverty, Institutional and Behavioral Economics, International Relations/Trade, Marketing, Productivity Analysis, Research and Development/Tech Change/Emerging Technologies, Resource /Energy Economics and Policy,

Cloning and characterisation of a maize carotenoid cleavage dioxygenase (ZmCCD1) and its involvement in the biosynthesis of apocarotenoids with various roles in mutualistic and parasitic interactions

Colonisation of maize roots by arbuscular mycorrhizal (AM) fungi leads to the accumulation of apocarotenoids (cyclohexenone and mycorradicin derivatives). Other root apocarotenoids (strigolactones) are involved in signalling during early steps of the AM symbiosis but also in stimulation of germination of parasitic plant seeds. Both apocarotenoid classes are predicted to originate from cleavage of a carotenoid substrate by a carotenoid cleavage dioxygenase (CCD), but the precursors and cleavage enzymes are unknown. A Zea mays CCD (ZmCCD1) was cloned by RT-PCR and characterised by expression in carotenoid accumulating E. coli strains and analysis of cleavage products using GC¿MS. ZmCCD1 efficiently cleaves carotenoids at the 9, 10 position and displays 78% amino acid identity to Arabidopsis thaliana CCD1 having similar properties. ZmCCD1 transcript levels were shown to be elevated upon root colonisation by AM fungi. Mycorrhization led to a decrease in seed germination of the parasitic plant Striga hermonthica as examined in a bioassay. ZmCCD1 is proposed to be involved in cyclohexenone and mycorradicin formation in mycorrhizal maize roots but not in strigolactone formatio

Potential Markets for Herbicide Resistant Maize Seed for Striga Control in Africa

Striga is an obligate parasitic weed attacking cereal crops in Subsaharan Africa. In Western Kenya, it is identified by farmers as their major pest problem in maize. A new technology, consisting of seed coating of herbicide tolerant maize varieties, has prove to be very effective in farmer fields. To bring this technology to the farmer, a sustainable delivery system needs to be developed, preferably through the private sector. To help of the seed companies develop a strategy, the potential market for this technology is hereby calculated, combines different data sources into a Geographic Information System (GIS). Superimposing secondary data, field surveys, agricultural statistics and farmer surveys makes it possible to clearly identify the Striga-prone areas in western Kenya. According to the analysis, the area has 212,000 ha in maize annually, with a population of 5.9 million people and a maize production of 480,000 kg, or 81 kg/person. Population density is high at 359 people/km2. A farmer survey reveals that 70% of farmers in this zone have Striga in their fields. Contingent valuation methods indicate that farmers' would be willing to buy on average 3.67 kg of the new seed each. This translates into a potential demand of 3,400 to 5,200 tons annually. Similar calculations, but based on much less precise data and expert opinion, not farmer surveys, estimate the potential market for herbicide tolerant maize against Striga at 64,600 tons annually, with an estimated value of $129 million.maize, Striga, Africa, weeds, pest control, Crop Production/Industries, Q12,