A new paradigm for improving yam systems

N. Maroya, R. Asiedu, P. Lava-Kumar, D. Mignouna, T. Abdoulaye, B. Aighewi, M. Balogun, U. Kleih, D. Phillips, A. Lopez-Montes, F. Ndiame, J. Ikeorgu, E. Otoo, N. McNamara; S. Abimiku, Sara Alexander, and R. Asuboah

In West Africa, yam (Dioscorea spp.) plays a very important role as a source of income, food security, and livelihood systems for at least 60 million people. The crop also makes a substantial contribution to protein in the diet, ranking as the third most important source. Farmers engage in yam cultivation for cash income and household food supply. Yam traditionally plays a significant role in societal rituals such as marriage ceremonies and annual festivals, making the crop a measure of wealth. Yams therefore have significance over and above other crops in the region. At the regional level, yam seems to be a superior economic good in all countries. As incomes increase, consumers shift from cassava to yam. This is related in part to regional cultural values and consumer preferences, which is mainly due to the relative ease in consumer food preparation.

Despite its importance in the economy and lives of many people, yam faces many constraints that significantly reduce its potential to support rural development and meet consumers’ needs as an affordable nutritional product. Unavailability and high cost of high quality disease-free seed yam is a major constraint in West Africa. This is followed by high levels of on-farm losses of tubers during harvesting and storage, low soil fertility, and high labor costs associated with land preparation and staking. Other constraints include losses due to diseases caused by viruses and fungi and nematode attack. Scale insects, tuber beetles, and termites affect the tubers in some areas. These effects are experienced more in the dry savannah agroecologies where yam cultivation is rapidly expanding due to the shrinking arable land in the traditional moist humid areas. In addition, the seed yam system in West Africa is mainly informal and entirely market driven.

Yam Improvement for Income and Food Security in West Africa (YIIFSWA) was initiated to increase yam productivity of 200,000 smallholder farmers (90% with less than 2 acres) in Ghana and Nigeria by 40% (2011 to 2016), and deliver key global goods research products that will contribute to the sustainable development of the yam sector.

Early gains

The project started by identifying yam production systems with partners (Fig. 1).

The yam value chain surveys with farmers, marketers (including exporters), transporters, and processors helped to estimate the cost of production of ware and seed yam, analyze costs and benefits of yam transaction, and identify major ware yam supply and distribution routes in both Nigeria and Ghana. Detailed value chain analysis has shown that yam production is a profitable business and yam farmers are able to generate substantial income from the production of tubers. But at the same time, production costs tend to be high (in particular for seed yam and hired labor) and selling prices depend on the season. There is significant price variability between the new yam season (August to October), the peak season (November to April), and the slack season (May to July). During peak seasons there is much yam in the markets but because of unavailability of good storage facilities, yam are sold at the lowest prices (Fig. 3). The gross margins can be negative if farmers get the timing of their harvest wrong, or are unable to sell at times when prices are higher.

YIIFSWA baseline studies conducted in 600 and 800 households, respectively in Ghana and Nigeria, indicated that only 3% and 10% households are headed by females in Nigeria and Ghana. Land was by far the major natural capital for small-holder farmers in yam-growing areas. The average farmland available was about 2.4 ha in Nigeria and 2.7 ha in Ghana. Priority has been given by households to yam over other food and cash crops. The areas under yam cultivation are generally small and the primary objective of small-holder farmers is to meet subsistence needs.

To develop the capacity of farmers organizations (FOs) by linking them to service providers (SPs) that would offer demand-driven services, a profiling exercise was conducted on 77 and 44 FOs and 40 and 17 SPs in Nigeria and Ghana, respectively. Overall, the performance indicators revealed that the selected FOs in Nigeria performed better than the ones in Ghana, in terms of quality of governance, internal management, value chain management, and marketing strategy. However the selected Nigerian FOs performed poorly, compared to Ghana counterparts, in the internal management and operations indicators.

Over 90% of the farmers use tubers harvested from the previous season as ‘seed yam’ or sourced from local markets, which are of poor quality due to pest and disease attack and lack of seed yam replacement. To improve the quality of farmer-saved seed yam, two NGOs—the Missionary Sister for Holy Rosary (MSHR) in Nigeria and Catholic Relief Services (CRS) in Ghana—have taken on the responsibility to train yam growers on seed yam multiplication using minisett technique combined with seed treatment to protect them from nematodes and fungal attack. So far, about 16,784 farmers were trained in Nigeria and Ghana.

The seed and ware yam sanitation challenges were also tackled. Surveys were conducted to identify pest and disease prevalence to establish appropriate strategies to control biotic threats to seed yam and ware yam. Virus diagnostics has been simplified to detect major yam-infecting viruses, Yam mosaic virus (YMV), Yam mild mosaic virus (YMMV), and Cucumber mosaic virus (genus, Cucumovirus), through a multiplex PCR-based assay.

Breeder seed yams produced in 2012 by Crops Research Institute (CRI) in Ghana and National Root Crops Research Institute (NRCRI) in Nigeria were handed over respectively to the Grain and Legume Development Board (GLDB, Ghana) and National Agricultural Seeds Council (NASC, Nigeria) for generation of foundation seed yam.

The breeder seed yam under production in 2013 is 0.8 ha and 0.5 ha, respectively for Nigeria and Ghana. GLDB has taken the challenge in Ghana and has a 1.5-ha foundation seed production site at Afraku (Ashanti region); while in Nigeria NASC selected two private seed companies (Greengold Construct Nigeria Ltd. and Romarey Ventures Nigeria Ltd.) that were engaged in foundation seed yam production for the first time.

New techniques such as aeroponics and temporary immersion bioreactors systems (TIBS) were effectively established at Ibadan. Results of experiments on the use of aeroponics system were encouraging for both pre-rooted planted and direct planting of vine cuttings of D. rotundata and D. alata. The successful growth of yam on the aeroponics system is reported for the first time with production of microtubers and mini-bulbils.

The TIBS is reported on yam in general, and in only one article for D. rotundata. YIIFSWA established a TIBS running on automated computer system with remote control through Internet. The 128 units of TIBs can produce a minimum of 12,800 plantlets per cycle. The running of the TIBs and the aeroponics systems for breeder or foundation seed yam production will speed up the generation of initial stocks of seed yam to supply the formal seed system.

Integrating available technologies, local and improved varieties to increase yam productivity is also another key objective of the project. Improved varieties with good performance in low soil fertility and drought stressed environments, and in staked and no staked system have been identified (table). The integration of landraces with seed selection and treatment, effective weed control, fertilizer application under no-stake system has indicated yields of 50% above the local technology. Studies have also determined that choice of yam varieties could be same for both men and women farmers and sometimes preferences differ.

For an effective operational seed system the capacity building of the players is key. To that effect national training workshops were organized: breeder and foundation seed production training workshop in Ghana and Nigeria; seed yam quality management protocol (QMP), yam virus disease diagnostics. In addition many partners (NASC, GLDB, CRI; SARI, CRS, MSHR, etc.) have organized training workshops for different stakeholders mainly on minisett technique for yam propagation.


In 24 months of project implementation, significant results were achieved on baseline studies, value chain analysis, farmers’ organization profiling, farmers training, and participatory selection of new genotypes. New techniques on high ratio propagation (aeroponics and TIBS), novel methods to develop virus-free planting materials, and the multiplex RT-PCR test for simultaneous detection of major viruses infecting yam, were successfully established. The formal seed yam system has been initiated and training have started. These initial successes are expected to pave a way to tackle greater challenges confronting the seed yam sector in West Africa.

Amazing maize

maize_100Research on maize improvement by IITA and partners, including CIMMYT, shows increased harvests and enhanced livelihoods of farmer-beneficiaries in sub-Saharan Africa. Total net benefit from maize research in West Central Africa from 1981 to 2005 alone using varieties from IITA, CIMMYT, and national programs is estimated at US$6.8 billion.

Issue 10, March 2013

Breakthroughs in maize breeding
Extra early white maize hybrids
Ensuring the safety of African crops
Helping farmers benefit from drought tolerant maize
New maize brings hope
Promoting drought tolerant maize
Saving maize from Striga
Ecofriendly bioherbicide
Developing aflasafeTM
Drought tolerant maize for Mali

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Drought tolerant maize is good for farmers and business in Mali

Vincent Defait, v.defait@gmail.com

Excellent outcomes in farmers’ tests of drought tolerant maize in Mali—where rainless spells persistently wilt harvests and hopes—have increased the demand for maize seeds and raised the crop’s appeal.

Finishing his meal, 67-year-old Malian farmer Bakary Touré smiles and looks over his homestead’s courtyard where friends are eating a traditional corn paste. Some children watch; some women wash pots; a goat wanders among scrawny hens; and a donkey’s sporadic braying shakes the dusty afternoon. This is Kolokani, a village in the heart of a town of 7800 homes some 120 km north of Mali’s capital, Bamako.

“In September 2011, I had nothing to eat, so I sold my goats and chickens to feed my family,” says Touré, referring to a particularly poor harvest. As the head of a household of 22 people he was ready to abandon his homestead at the time but, as he says, “…Maize saved me.” On the advice of fellow farmers in a local cooperative in May 2012, Touré bought 20 kg of seeds of Brico, a drought tolerant (DT) variety with yellow kernels. Sown and managed using recommended practices, the US$15 purchase of seeds grew into a 1.6 t harvest that brought food security to Touré and his homestead. “I gave three bags to friends who will pay me back later,” he says, standing in front of his storage room. “With the 13 bags I have, I can feed my family for six months.”

Other Kolokani farmers have profited by producing and selling seeds of the DT varieties. Near a small warehouse that stores grain sacks, Oumar Traoré, president of the cooperative “The Good Seed”, remembers the first trials with the varieties. “We usually grew more groundnut and sorghum,” he says, “but when we learned that this maize was profitable and drought tolerant, we wanted to try it.” He and his peers grew it on small areas the first year but soon expanded their plots. “The following 2 years, I produced 6 t of maize, mainly to sell as seeds,” Traoré says, as his friends nod in agreement. “It brought me 1.5 million FCFA ($2900) and I bought cows and a motorcycle. Today, our main problem is the cost and availability of mineral fertilizer on the market. If we cannot buy enough in a timely manner, we have to cut back the maize area,” says Traoré. Despite this, he says that production of DT maize allows him to easily feed his family with 13 members and sell seeds for as much as $1/kg.

A new movement toward maize
That maize can save the day is surprising news in Kolokani where the yearly rainfall, 600 mm or less, has favored more water-sparing crops, such as sorghum, groundnut, and sesame. But Bakary Touré and Oumar Traoré are among thousands of Malian farmers taking up DT maize varieties.
“Mali is one of the countries in West Africa where maize production has expanded into areas where drought stress occurs intermittently,” says Abebe Menkir, IITA’s Maize Breeder, who works with Mali’s Institute of Rural Economy (IER) to develop DT maize varieties and make them available to farmers. “With these varieties, Mali has the opportunity to expand maize production into areas where it was not possible before because of droughts.”

“In Mali, DT maize could revolutionize the lives of farmers,” says N’Tji Coulibaly, an IER agronomist and head of its maize research program who is testing and promoting the new varieties with farmers. Mali is a landlocked country in West Africa of 15.5 million inhabitants. Less than 4% of the land is arable; 8 of every 10 citizens are engaged in agriculture or fishing around the Niger River. Since the mid-1990s, domestic maize production and consumption have grown significantly, based on the crop’s high yield potential and responsiveness to fertilizer, its capacity to alleviate food deficits, as well as its export potential and value for processing and food industries. “The introduction of DT maize seeds can speed the attainment of the Government’s main objective of food sufficiency for Malian farmers.”

Smallholder farmers earn a surplus by growing seeds
The varieties that Coulibaly and Menkir test and promote are products of the Drought Tolerant Maize for Africa (DTMA) project, implemented since 2006 by IITA and the International Maize and Wheat Improvement Center (CIMMYT), with funding from the Bill & Melinda Gates Foundation, the Howard G. Buffet Foundation, USAID, and the British Department for International Development.
In the IER office in Bamako, Coulibaly traces the beginnings of the DTMA project in Mali. “We worked with farmers to select the best seeds, those that adapt best to areas where drought is endemic,” he says. “From 2009, two early maturing open-pollinated varieties were released that farmers have dubbed Brico, the name of a town in Mali, and Jorobana, which means “no worries” in the Bambara language. In areas where drought can reduce production by 70%, DT maize is a godsend. Ideally, we should introduce one or two new DT varieties each year.”

IER also helps to teach farmers the skills and know-how to produce certified seeds. Among other things, this requires them to follow a schedule for applying fertilizer, weeding the plots, and maintaining enough separation between maize crops to avoid cross-pollination.

Best and timely practices
Coulibaly describes a series of marketing challenges that need to be addressed. “We must find a way to produce more basic seeds,” he says, referring to the seeds that are multiplied by companies and other commercial seed producers. “In particular, it is often necessary (for someone) to quickly buy the seeds the farmers produce because without money (from those sales), they have nothing to eat; they cannot wait for a potential buyer to knock on their door.” Coulibaly adds that, by the same token, farmers are not able to plan well for their own needs over the medium term. “In general, when a drought is looming, they all want DT seeds at the same time.”

These considerations do not seem to have reached Tanabougou, a village where only the minaret of the tiny mosque stands over the lot of concessions. The capital is only 40 miles away, but to get there one first needs to reach the paved road along a track on which only a few vehicles raise clouds of sand. Run down and often closed businesses in the city of Koulikoro, the capital of the eponymous region, give the impression that there has never been any impact on life in the villages. The Niger River is close, but it seems to belong to another world. In Tanabougou, it is the rain that supplies water to the crops. Animals, mainly goats and donkeys, crop the residues of harvest and the few tufts of grass under the trees.

In his banco concession where bright yellow maize cobs dry on a nga, a wooden roof and branches, another farmer, Benkeba Traoré, 56, says, “With traditional maize varieties, I was producing about 300 kg per year. Last year, with the drought tolerant variety Brico, I produced 2 t of maize and sold 800 kg as seeds to Faso Kaba, a seed business owned by a woman entrepreneur.” In two seasons Benkeba Traoré, who has to feed four adults and 12 children from 3.5 ha, was able to buy a pair of oxen and a plow, “Soon,” he says, “I will replace the branches which surround the concession with corrugated iron.”

The progress was also made possible by the training provided by the agronomists of IER and the technicians of Faso Kaba. For the past 3 years, the farmer has learned to isolate his seed production from other plots, to meet deadlines when spreading fertilizer, to recognize the quality of the soil, and to sow suitable seed varieties.

Rotating crops
When asked if he was not tempted to abandon the other crops, given the high yield of DT maize and the money it generates, farmer Traoré replies, “Last year, I reduced the area of sorghum and groundnut in favor of maize. Sorghum was a failure and maize saved me. But next year, it may be the other way round, so I prefer to continue to grow more cereal crops.”

The farmer now hopes to marry off his two oldest children and buy a motorcycle (about 300,000 FCFA or US$580) to travel to the village. “Today, I have no problems with the soudure,” Traore insists. All farmers in West Africa know about this difficult time between the end of the stock and the next harvest.

Lassana Diakite, 64, is reassured too. He chairs the cooperative from Koula, a neighboring village at the center of a little town with 25,000 inhabitants, several hours walk from the marketplace. Sitting on a wooden bench in the shade of a tree overlooking his concession, the farmer describes in a serious voice the various stages of maize cropping. “From plowing to sowing and harvesting, each step is recorded. I know when I need to weed, when I have to spread fertilizer, when I have to harvest … I even know my yields in advance. ” That is a lot of advantages for this head of a family of 35 people who inhabit parts of the banco concession.

In the first year, the farmer used 1.5 of his 12 ha for production of Jorobana seeds. The result: 1.7 t of maize harvested. Three years later, production has climbed to 4.6 t. “Drought tolerant maize beats conventional maize as the horse beats the donkey,” asserts the farmer.

The next tcheba seeds…
Looking at the nga, where the sun shines on his maize spread like gold nuggets, the farmer adds, “Next year I will sow 3 or 4 ha.” It is impossible for him to devote all his 12 ha to maize. “I do not have the labor,” he continues. “I would have to stagger the fields and interventions and that would compromise performance.”

Diakité acknowledges his new comforts, the oxen he recently acquired, the taxes he pays “with ease,” the education of his children, which is now more affordable, and the fertilizer for the sorghum that he can buy with the money generated by maize.

Back in Bamako, in his office at IER, Coulibaly dreams of the next generation of DT maize varieties. His team has just completed tests on hybrid varieties which are more productive. In 2013, Malian farmers should be able to grow the Tcheba variety meaning ‘big’ in Bambara. The agronomist said, “In Mali, with DT maize, we can speak of a success story…

Tanzanian president inaugurates new science building

The President of the United Republic of Tanzania, His Excellency, Dr Mrisho Jakaya Kikwete, in May, inaugurated IITA’s new science building in Dar es Salaam, Tanzania.

The construction of the science building represents an investment of over US$4 million and is part of IITA’s efforts to strengthen its research capacity and that of its partners in sub-Saharan Africa.

“The science building is a symbol of IITA’s commitment to continue waging the fight against hunger and poverty and boost agriculture through capacity development and improve the livelihoods of smallholder farmers in East Africa through its research-for-development efforts,” says Dr Nteranya Sanginga, IITA Director General.

Citing IITA for its R4D work in http://pangeagiving.org/cheap/ sub-Saharan Africa, President Kikwete lauded the construction of the science building, saying that any effective socioeconomic transformation which would have levitra online cheap a significant impact on poverty reduction in Tanzania and Africa should be anchored on agriculture.

The inauguration was followed by a tour of the new building and exhibition booths showcasing IITA’s work in East Africa, and a workshop with the theme “Grow Africa and the role of agricultural research by national systems, IITA, and its partners.”

The state-of-the-art and environmentally friendly Science Building has five modern laboratories with a capacity to host 70 researchers.

Nigeria releases improved cassava varieties

Nigeria has released two new improved cassava varieties developed through a collaborative effort between IITA and the Nigerian Root Crops Research Institute (NRCRI), Umudike. The two varieties are originally recognized as IITA-developed genotypes IITA-TMS-I982132 and IITA-TMS-I011206, now known as UMUCASS 42 and UMUCASS 43, respectively.

Both varieties performed well in different cassava production regions of Nigeria with high yield, high dry matter, and good disease resistance. The roots of these varieties are yellow and contain moderate levels of provitamin A.

The potential maximum yield of the two varieties is between 49 and 53 t/ha, according to pre-varietal release trials that were conducted between 2008 and 2010. Local varieties produce less than 10 t/ha. The varieties are also resistant to major pests and diseases that affect cassava in the country including cassava mosaic disease, cassava bacterial blight, cassava anthracnose, cassava mealybug, and cassava green mite.

The varieties are good for high quality cassava flour—a trait sought after by researchers for the cassava transformation agenda in Nigeria; have high dry matter which is positively related to starch and important for cassava value chain development; have high leaf retention which is positively related to drought tolerance and is crucial for cassava production in the drier regions and in mitigating the impact of climate change, with moderate levels of betacarotene for enhancing nutrition.

Cassava project launches database

Cassavabase, a database that promotes open access data sharing, was launched recently.

IITA is a major contributor of data to www.cassavabase.org and will host this information resource through the NEXTGEN Cassava project.

Cassavabase features phenotypic and genotypic data generated by cassava breeding programs involved in the NEXTGEN Cassava project at Cornell University supported by a US$25.2 million grant from the Bill & Melinda Gates Foundation and the Department for International Development of the United Kingdom.

The database makes the data immediately and openly accessible to the whole cassava community prior to publication. It is being developed by Lukas Mueller, adjunct professor of plant breeding and genetics at Cornell, at the Boyce Thompson Institute in Ithaca, New York.

Cassavabase provides a “one-stop shop” for cassava researchers and breeders worldwide. In addition to phenotypic and genotypic data, Cassavabase offers access to all genomic selection analysis tools and phenotyping tools developed by the NEXTGEN Cassava project, and links to auxiliary genome browsers, ontology tools and social networking tools, for the cassava community.

Biocontrol product reduces mortality in poultry

A study by scientists from IITA and the University of Ibadan, Nigeria, has found that poultry fed with maize treated with aflasafeâ„¢ experienced reduced mortality in addition to other benefits.

Results from the feeding experiment involving 1,020 broilers showed that the use of maize from aflasafeâ„¢-treated feeds reduced mortality rate by 43.9%, feed intake dropped by 10.4%, and there was an increase of 3.3% in feed conversion ratio.

The results show the impact of aflasafe™—a biological control product developed by IITA for controlling aflatoxins.

Produced by toxigenic strains of Aspergillus flavus, aflatoxins have become a menace in developing countries, contaminating about 25% of grains produced in the region. The aftermath effects of consuming aflatoxin-contaminated grains include stunting in children, liver cancer, and even death.

Ecofriendly bioherbicide approach for Striga control

Abuelgasim Elzein, a.elzein@cgiar.org, and Fen Beed

Root parasitic weeds of the genus Striga are a significant constraint to cereal and cowpea production in sub-Saharan Africa. They can cause total crop losses particularly during drought, in infertile soils and cereal monocropping. Striga causes annual losses of US$7 billion and affects incomes, food security, and nourishment of over 100 million people mostly in sub-Saharan Africa.

Each Striga plant can produce thousands of seeds, viable for over 10 years. Their intimate interaction with different host plants prevents the development of a silver bullet control technology that subsistence farmers can adopt. Hence, it is widely accepted that an integrated approach to Striga management is required for which biocontrol represents a crucial component.

Bioherbicide innovation
A bioherbicide is a plant pathogen used as a weed biocontrol agent (BCA), which is applied at sufficient rates to rapidly cause a disease epidemic that kills or severely suppresses the target weed. The use of biocontrol technology to manage Striga is a desirable control method as it is environmentally friendly, safe to farmers and crop consumers, specific to the target host, and has the potential to be economically viable. In addition, biological control also assists in the development of a balance of nature, the creation of more biodiversity, and sustaining of complex ecological interactions.

Since the early 1990s, a series of intensive disease surveys in many countries of sub-Saharan Africa has evaluated hundreds of microorganisms for their pathogenicity and virulence against Striga. Fusarium oxysporum Schlecht isolates have been the most promising. However, the discovery of a highly effective pathogen is only one step in the process of developing bioherbicides, for which the inoculum mass production, formulation, delivery, and storage ability must be optimized, and the mode of action, host specificity, and biosafety evaluated and fully understood.

The most widely studied and used fungal isolate that met all requirements for a potential bioherbicide for Striga is F. oxysporum Schlecht f. sp. strigae Elzein et Thines (isolates Foxy2 and PSM197). These are highly virulent, attack Striga in all growth stages—from seed to germination, from seedling to flowering shoot; protect the current crop yield; and prevent seed formation and dispersal.

F. oxysporum f. sp. strigae is highly host-specific to the genus Striga, and does not produce any known mycotoxic compounds. Thus, its use does not pose health risks to farmers, input suppliers, traders or consumers or threaten crops or the environment. Its unique DNA constitution differs from other forms of F. oxysporum deposited in GenBank, known to cause crop diseases. Indeed, this ensures its biosafety and greatly facilitates its wider application and use as a bioherbicide.

In addition techniques for massive production of inoculum of F. oxysporum f. sp. strigae was optimized based on simple and low-cost methods and using inexpensive agricultural by-products available in sub-Saharan Africa. The chlamydospores produced by this fungus have the advantage of being able to survive extreme environmental events while still remaining viable. This is an important feature required for a BCA suited to hot and dry climatic conditions of cereal production in sub-Saharan Africa, and to produce stable, durable, and pathogenic propagules.

Extensive research by the University of Hohenheim (UH, Germany), IITA (Benin), McGill University (Canada), and Institute for Agricultural Research – Ahmadu Bello University (Nigeria), has enhanced application of F. oxysporum f. sp. strigae, its formulation into bioherbicidal products, and its delivery for practical field application. The Striga bioherbicide contains the Striga host-specific F. oxysporum f. sp. strigae, applied in massive doses to create a high infection and disease level to kill or severely suppress Striga.

Promotion in West Africa
The bioherbicide is a component of the IITA-led project, Achieving sustainable Striga control for poor farmers in Africa, funded by the Bill & Melinda Gates Foundation to intensively promote technologies to combat Striga in sub-Saharan Africa. The project will validate the potential of the bioherbicide seed treatment technology across major Striga-infested agroecological zones and maize-based farming systems, while also confirming the biosafety and developing molecular detection tools. Here are the highlights of the results:

Technology validation: Several multilocation trials were conducted under natural and artificial Striga infestation across two agroecological zones in northern Nigeria to evaluate the efficacy of Striga bioherbicide (F. oxysporum f. sp. strigae). The inoculum produced by UH and SUET seed company was delivered as a film-coat on maize seeds (see below).The application of the bioherbicide technology in combination with Striga resistant maize reduced Striga emergence by 73% and 39%, compared to the susceptible and resistant controls, respectively, and prevented 81% and 58% of emerged Striga plants from reaching flowering and 56% and 42% of the maize plants from attack by Striga (see next page). The combination of bioherbicide with Striga susceptible variety significantly reduced Striga emergence by 53%, resulting in 42% reduction in number of flowering plants and in 21% increase in grain yield compared to the susceptible control.

In addition, disease symptoms were recorded on emerged Striga plants parasitizing maize plants coated by the bioherbicide. The reduction in Striga emergence across maize varieties indicates the effectiveness of the bioherbicide to attack seeds under the soil surface. The synergistic effect of the bioherbicide technology combined with the Striga resistant maize is expected to reduce the Striga seedbank and thus the impact of Striga on subsequent maize crops.

Biosafety: To further ensure the safety of Striga BCA and to demonstrate and increase awareness among farmers, regulatory authorities, and stakeholders, a wide host range study was carried out using 25 crops in collaboration with IAR-ABU and the Nigerian Plant Quarantine Service (NPQS)  under field and screenhouse conditions in Nigeria. Results revealed that none of the test plants showed any infection by the biocontrol agent both in the field and screenhouse, and no detrimental growth effects were measured or visual losses to plant health recorded in any of the inoculated crops tested, i.e., inoculation with the Striga BCA did not cause any delay in emergence, and a decrease in plant height, plant vigor, chlorophyll content per leaf, shoot fresh and dry weight. Hence, the Nigerian regulatory authorities (NPQS, NAFDAC) and other stakeholders were satisfied and confident that no disease was produced on plants other than Striga by the BCAs and that it is safe to use. In addition, a mycotoxin produced by Striga bioherbicide  F. oxysporum f. sp. strigae was analyzed and evaluated by our project partner, the University of Stellenbosch in South Africa. An evaluation of existing isolates of F. oxysporum f. sp. strigae does not produce well-known mycotoxins (e.g., Fumonisin and Moniliformin) that pose a threat to animal or human health. This finding further confirms the safety of this bioherbicide.

Molecular detection tools: Development of a monitoring tool specific to the Striga bioherbicide is important to certify inoculum quality, monitor the presence and persistence of the BCA in soils, and validate its environmental biosafety. UH is developing a monitoring tool.

The AFLP fingerprinting technique was successfully used in developing a primer pair capable of differentiating the F. oxysporum f. sp. strigae group from other Fusarium species. In addition, the monitoring tool has shown a high specificity for isolate Foxy2 and was used to monitor its spread and persistence in rhizobox experiments under different management practices using Kenyan soils. This promising result provides a proper baseline to further the existing primer set.

Bioherbicide + pesticide technology: The novel combination and integration of the bioherbicide technology plus imazapyr herbicide for Striga control with pesticides in a single-dose seed treatment to control fungal pests offers farmers with maize seed that is able to achieve its yield potential. The use of each technology (BCA or imazapyr) has been shown to be effective when applied independently using seed coating techniques, but have not been integrated.

The compatibility of Striga BCAs with different pesticides (herbicides and fungicides with insecticide components) was studied in vitro in the laboratory. Striga BCAs showed excellent compatibility with imazapyr (a herbicide seed coating used in combination with IR maize to control Striga), Metsulfuron Methyl (MSM) (a herbicide seed coating developed by DuPont to control Striga in sorghum), and glyphosate (an intensively used herbicide). A similar result was also achieved with the commonly used seed treatment fungicides at the recommended application doses.

Accordingly, doses and complementary seed coating protocols for the three compatible technologies (BCA, herbicide, and fungicides) have been developed and IR maize seeds were successfully coated with a single-dose seed treatment of BCA inoculums and imazapyr. The results showed that imazapyr did not interfere with the BCA during seed coating, with BCA growth and sporulation after coating, and with IR maize seed germination. Seeds of IR maize varieties can thus be coated with the herbicide and the BCA and then fungicide and delivered to farmers using the same input pathway. Screenhouse and field trials are being carried out to generate data on the combined efficacy of the applied technologies. The demonstrated compatibility of Striga BCA with the different pesticides that contain a wide range of active ingredients indicate that the combination and delivery of the Striga bioherbicide technology with a large number of pesticide products is possible. These findings are expected to provide a triple action seed coating package for direct control of Striga and fungal diseases of maize in sub-Saharan Africa.

Suitability to African farming systems
Our strategy for scaling-up the bioherbicide innovation is based on using technology appropriate to Africa to ensure that sustained production of the bioherbicide is feasible at a cost affordable to African small-scale farmers. The seed-coating treatment requires significantly less inoculums, establishes the BCA in the cereal rhizosphere, i.e., the infection site of Striga, and provides a simple, practical, cost-effective delivery system for adoption by input suppliers to subsistence farmers. Arabic gum as a coating material has been shown to increase the rate of mycelia development and enhance BCA sporulation. Its availability in sub-Saharan Africa at a low price is an additional economic advantage. A commercial seed coating process, developed and optimized at UH with SUET Seed Company in Germany, is being transferred and adapted at IITA, Ibadan, to be used as an experimental production unit for capacity building and as a model for eventual transfer of seed treatment technology to the private sector after validation.

One unique advantage of this bioherbicide is that the ability of Striga to become resistant to it is virtually unknown as a consequence of the suite of enzymes and secondary metabolites that the BCA produce to become pathogenic and virulent against the target (Striga). Hence after validation, delivering the bioherbicide technology in combination with resistant maize or with the herbicide imazapyr is expected to increase efficacy in controlling Striga. Bioherbicide and other compatible technologies have different modes and sites of action against Striga, and in a combination they will have a much greater chance of reducing the potential risk of development of resistance to a single technology (resistant varieties or herbicides) used separately and repeatedly.
The potential delivery of coated seeds of resistant maize with bioherbicide in one package to farmers using the same input pathway will reduce transaction and application costs and enhances the economic feasibility and adoptability of the technologies. Similarly, compatibility of BCA with imazapyr and fungicides allow seed coating of IR-maize with bioherbicide, imazapyr, and fungicides with a single-dose seed coating application.

Future plans
Currently, large-scale field testing is ongoing and is being implemented to further validate bioherbicidal efficacy across two agroecological zones where the common scenarios for maize infestation by Striga in northern Nigeria are represented. For understanding of farmers’ preferences and perceptions, socioeconomic analysis and cost-benefit analysis of bioherbicidal technology based on field data/surveys and interviews, current market information, and links with other Striga control strategies will be undertaken. After validation, dissemination and commercialization will be promoted through private sector partnerships and integrated with other control options such as resistant varieties, IR varieties combined with seed treatment with imazapayr, crop rotation with legumes, and soil fertility management practices, to achieve sustainable management of Striga.

IITA (Dr F. Beed, Dr A. Elzein & Dr A. Menkir), Institute for Agricultural Research – Ahmadu Bello University (Dr A. Zarafi), Nigeria; University of Hohenheim (Prof G. Cadisch, Dr F. Rasche & Prof J. Kroschel), Germany; The Real-IPM Company Ltd (Dr H. Wainwright), Kenya; University of Stellenbosch (Prof A. Vilioen), South Africa; and McGill University (Prof A. Watson), Canada.

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