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New network analysis approach to mitigate spread of potato disease

The spread of disease in potato seed systems is a major risk to production and livelihoods. As root and tuber crops are propagated vegetatively, pathogens and pests can accumulate in planting material over successive cycles of propagation and lead to poor quality seed. Balancing the need to manage and control this, while also facilitating the efficient spread of improved varieties among farmers is a challenge. Addressing approaches for evaluating and mitigating the risk of disease in seed systems is an important research area for the CGIAR Research Program on Roots, Tubers and Bananas (RTB).

There are around 85,000 potato farmers in Ecuador, of which 75% are estimated to be small-scale producers. Photo courtesy Garrett Lab.

To address this need, we developed a new method of analysis to identify the most important individual stakeholders in a seed system – such as farms, seed multipliers and institutions – who should be a focus for disease detection and management efforts. We modeled and evaluated the spread of disease in farmer seed provisioning networks, or seed systems. We focused on a network of seed tuber transactions for members of a regional potato farmer consortium in Ecuador, called CONPAPA. An interactive interface allows users to see how a new disease is likely to spread through this network.

CONPAPA is a regionally successful farmer cooperative that helps members to buy disease-free planting material and provides training on how to effectively manage pests and diseases. The cooperative also sells potato that member farmers produce in a wide array of markets. In this case, we found that the CONPAPA seed and potato processing center, the main market in Ambato, central Ecuador, and some specific farmers were high risk, high return sites for disease detection and management. Among the CONPAPA members, the use of disease free seed tubers for planting was found to be 36% – much higher than the 2% previously reported for Ecuador.

We also examined the sources that farmers relied on for information about pest and disease management. Advice from staff at agrochemical stores was common, but was considered by farmers to be significantly less reliable than other sources. Farmer access to information, based on the number and quality of sources, was found to be similar for both women and men. However, women had a smaller amount of the market share for seed-tubers and ware potato.

Mitigating the spread of potato disease is an essential step towards helping boost Ecuador’s potato production, which is lower than neighbors, Colombia and Peru. Photo courtesy Garrett Lab.

The evaluation of seed system networks provided input for scenario analyses to evaluate potential improvements that could be made to the system. In this simple system, CONPAPA staff and facilities, the market in Ambato, small agro-chemical stores and certain farms were identified as priorities for disease management interventions based on the roles they played as sources of information or seed for farmers in the area. Suggested interventions to mitigate the spread of poor quality potato planting material include training on disease management, monitoring and improved variety dissemination.

This work was undertaken as part of an RTB project that seeks to reduce the impacts of “seed degeneration” in root and tuber crops, including potato, sweetpotato, yams, cassava and bananas. Models of disease spread, like the one we present, take into account the accumulation and spread of disease in planting materials, and can be applied to more systems to evaluate strategies for controlling risk. We show how the structure of seed networks influences the risk for seedborne disease, and can inform farmers, scientists and managers about where to invest effort to reduce risks to farmers.

The CONPAPA system is relatively small and simple, but the analyses we have developed here are also being applied to larger and more complicated systems, as part of the development of a general theory of seed system deployment in the CGIAR Research Program on Roots, Tubers and Bananas.

This blog was contributed by Chris Buddenhagen (University of Florida), Karen Garrett (Garrett Lab) and Jorge Andrade (International Potato Center), with Holly Holmes (RTB).

Buddenhagen, C.E., Hernandez Nopsa, J.F., Andersen, K.F., Andrade-Piedra, J., Forbes, G.A., Kromann, P., Thomas-Sharma, S., Useche, P., Garrett, K.A., 2017. Epidemic Network Analysis for Mitigation of Invasive Pathogens in Seed Systems: Potato in Ecuador. Phytopathology 107, 1209-1218. Access the open access article: doi:10.1094/PHYTO-03-17-0108-FI 

Taking agricultural innovations to scale: RTB scaling fund awards first grants

Researchers who develop new technologies often face challenges in translating them into adapted innovations that people and enterprises will use. The CGIAR Research Program on Roots, Tubers and Bananas (RTB) consequently created a flagship project dedicated to improving livelihoods at scale (Flagship 5), which is facilitating the design and implementation of strategies for scaling innovations to achieve the greatest possible impact.

One of the mechanisms created for this is the RTB Scaling Fund, which recently awarded its first grants to three teams of scientists as part of a broader effort to help them take their innovations to scale. Those teams will share approximately US$2 million to scale three promising technologies: 1) an approach for controlling the banana disease BXW known as single diseased-stem removal (SDSR); 2) a method for conserving sweetpotato roots to produce planting material known as Triple S; and 3) a technology for turning cassava peels into an ingredient of animal feed.

A woman reads a flyer as part of efforts to increase the uptake of the SDSR technique. Photo: B.vanSchagen/Bioversity International

“The scaling fund is truly unique in the CGIAR and it shows RTB’s commitment to the scaling of innovations,” says Dr Marc Schut, a researcher with the International Institute of Tropical Agriculture (IITA) and Wageningen University & Research (WUR) who leads Flagship project 5.

Schut observes that researchers tend to invest much more time and energy in developing and improving technologies than in understanding the market, policy and cultural aspects of the enabling environment that can facilitate or hinder their efforts get those technologies to farmers or other end-users. He explains that in addition to the funding awarded for the three technologies, the Flagship 5 team will provide guidance in the design of scaling strategies and monitoring progress toward impacts, while drawing lessons to inform critical thinking about scaling processes in agri-food systems.

According to RTB Program Management Officer Claudio Proietti, the Scaling Fund adds value to and works in synergy with existing projects and ongoing partnerships. He explains that RTB management sent out a call for concept notes on innovations seeking Scaling Fund support in August that resulted in 12 submissions. An independent panel assessed the scaling readiness of those technologies and asked five of the teams to submit full proposals. Those five innovations were assessed and scored, and the three with the highest scores were awarded funding.

SDSR allows smallholders to reduce BXW incidence without destroying large numbers of plants. Photo G.Blomme/Bioversity International

One of the innovations to be funded is SDSR: a method for managing BXW by cutting down symptomatic banana plants, sterilizing tools, and removing flowers from healthy plants to prevent insects from infecting them. SDSR allows smallholders to reduce BXW incidence to very low levels without destroying large numbers of banana plants, which means they can continue producing fruit and earning money.

Dr Boudy Van Schagen, a social scientist with Bioversity International, explains that while approximately 20,000 households in Central and East Africa have adopted SDSR, more than 20 million households in the region have been impacted by BXW. The initiative’s goal is to get approximately 100,000 households in Burundi, DR Congo, Rwanda and Uganda to adopt SDSR while making it more gender-responsive and adaptive to farmers’ needs.

Another innovation funded, Triple S (Storage in Sand and Sprouting), involves storing sweetpotato roots in sand during the dry season and planting them in seedbeds 6-8 weeks before the rains are expected, which allows farmers to produce enough vine cuttings to plant when the rains resume. Margaret McEwan, a social scientist working on seed systems at the International Potato Center (CIP), explains that Triple S has been successfully tested in varied agroecologies and used by farmers across nine sub-Saharan African (SSA) countries. CIP and partners will use the Scaling Fund grant to train trainers and run gender-responsive mass media campaigns with the aim of getting 80,000 farmers in Ethiopia and Ghana and other spillover countries to take up the technology.

“We want to institutionalize Triple S into existing programs,” she says, adding that the scaling efforts will piggyback on other sweetpotato vine dissemination interventions.

Triple S involves storing sweetpotato roots in sand during the dry season and planting them in seedbeds 6-8 weeks before the rains are expected. Photo: E.Abidin/CIP

McEwan notes that the process of applying for the Scaling Fund included assessing Triple S’s scaling readiness and developing a theory of scaling. This led her team to modify the approach to include training in best agronomic practices and positive selection of roots, in order to produce better harvests. She adds that because Triple S scaling will be done in collaboration with the Sweetpotato for Profit and Health Initiative, which works across 17 SSA countries, there is potential for using strategies developed and refined in this initiative to scale Triple S elsewhere.

“Scaling requires a certain level of standardization, but we need to learn how to ensure that scaling can also be adaptive and responsive to local contexts,” says McEwan.

The third innovation funded is a technology to turn cassava peels – a waste product from garri and lafun production in Nigeria – into a high quality cassava peel (HQCP) mash that can be substituted for 15-60% of the maize in livestock or fish feed. According to Dr Iheanacho Okike, an agricultural economist consultant with IITA, Nigeria’s cassava processing industries produce more than 12 million tons of cassava peels annually, the disposal of which constitutes an environmental problem but holds potential for income generation. While a few factories in Nigeria have already adopted the HQCP technology, IITA and partners plan to engage government institutions, cassava processors and feed producers to scale it out for greater economic and environmental impact.

“Involvement in the competition for the Scaling Fund helped us to deepen our thinking around what we should be doing, our scaling strategies and/or models, and who we should be engaging with,” says Okike.

HQCP powder can replace 15-60% of maize in animal feed. Photo: I.Okike/IITA

Proietti notes that the two innovations that weren’t funded this year are also quite promising and should be top contenders for the next round of funding. Those innovations are: 1) an initiative to expand the use of OFSP puree in baked goods in East and Southern Africa; and 2) the promotion of a technology for waxing cassava roots to increase their shelf life in Tanzania and Uganda.

According to Proietti, the process of developing proposals and assessing technologies’ scaling readiness served as an exercise that helped researchers better understand their innovation’s adaptability to the conditions in target countries. “We’ve encouraged scientists to take a more systems view of their technologies and address how well adapted they are to the real world,” he says. “This process is resulting in new insights on how to improve scaling strategies, partnership arrangements and a learning process that can support adaptive management.”

Schut notes that while each context is unique in terms of agroecology, end-user needs, market, infrastructure and policies, there will be lessons learned from these scaling experiences that can be applied to other crops or technologies. He adds that the Scaling Fund contributes to critical reflection on the return of RTB investments, helping to determine which investments have the highest potential for scientific progress towards achieving agricultural development.

“We have already learned a lot, and many scientists have provided us with feedback that the scaling fund has made them much more aware that scaling requires other types of approaches, capacities and partnerships,” he says. “However, the principle objective is to ensure that the initiatives funded contribute to achieving the RTB outcomes.”

by David Dudenhoefer

RTB Symposium at International Conference on Global Food Security to address the challenges of scaling agricultural innovations

Whereas private companies have successfully rolled out new technologies in less-developed countries, innovations developed by research centers to help smallholders improve their food security and incomes often reach only a fraction of the people they were created to help. As the stakes for agricultural research for development rise in an increasingly warm and crowded world, this gap between research and impact is becoming a major concern of governments, international organizations and donors.

In an effort to help researchers develop innovations that people are more likely to use, the CGIAR Research Program on Roots, Tubers and Bananas (RTB) has teamed up with Wageningen University & Research (WUR), in the Netherlands, to develop, test, and apply ‘science of scaling,’ in order to make better decisions about which kinds of innovations, research and partnership investments will lead to development impacts. Scientists who are involved in these efforts will share their insights and research on scaling during a symposium this Sunday, December 3, as part of the Third International Conference on Global Food Security, in Cape Town, South Africa.

Entitled “Science of scaling: connecting the pathways of agricultural research and development to improve rural livelihoods,” the symposium brings together scientists and development professionals from several international research centers and companies. Their presentations will cover cases ranging from work to improve smallholder cocoa and coffee production in sub-Saharan Africa (SSA) to an International Potato Center led partnership initiative that has gotten nutritious, improved sweetpotato varieties to more than 2.8 million households in SSA.

Getting the products of agricultural research to the smallholders who need them can be a major challenge. Photo H.Rutherford/CIP

For Dr Marc Schut, a researcher with IITA and WUR and the leader of the RTB Flagship on Improved Livelihoods at Scale, the first lesson is that “scaling does not happen just like that. It requires strategizing, competence and investment.”

Schut adds that the good news is that a growing number of tools are available to help research-for-development scientists make better decisions in terms of the type of research they do and the partnership investments they make. “Evidence-based design, implementation, and monitoring of scaling strategies can help us to achieve better impact,” he says.

One of the symposium’s presenters, Dr Elisabetta Gotor, who heads the Development Impact Unit at Bioversity International, observes that most scientist don’t know how to go about getting the innovations they develop into the hands of large numbers of users. She explains that when a researcher develops a new agricultural innovation – whether it be an improved crop variety or an approach for managing a crop pest or disease – it is important that they start by analyzing and measuring the likelihood of its success in the given context.  She adds that this is a complex task, because there are gender and cultural elements that must be taken into account, but it is essential for an innovation to be successful.

“As researchers, we have the obligation not only to develop technologies, but also to ensure that those technologies are transformed into products that are usable by the populations we want to influence,” Gotor says.

Scaling agricultural innovations requires understanding local demand and cultural elements, a well designed strategy and investment. Photo G.Smith/CIAT

Gotor’s presentation will cover efforts by RTB scientists to connect foresight research and impact assessments in order to establish feedback loops through which those methods can inform one another. She notes that this will enhance the scaling of innovations while producing information that donors or policy makers can use to guide future investments in research for development.

Adebowale Akande, an Agribusiness Development Specialist at the International Institute of Tropical Agriculture (IITA), will give a presentation on scaling the Alfasafe bio-control product in Nigeria, in order to reduce aflatoxins in agricultural value chains, as well as current efforts to turn that technology over to the private sector. He recommends that researchers demonstrate the proof of concept of their innovation to the private sector, engage both the private and public sectors to create an enabling environment, and gain access to financing to successfully scale their innovations.

Dr Graham Thiele, Director of RTB, will present an overview of the measures that RTB has taken to help scientists assess the readiness of their innovations for scaling and work toward getting them widely adopted. “There is huge interest right now in scaling and RTB is ahead of the curve on its thinking,” he explains. “Scaling is right at the top of the agenda for many donors as they look for enhanced impact.”

People attending the International Conference on Global Food Security can learn more about scaling by attending the “Science of Scaling” symposium this Sunday, December 3 at 12:30. It will be held in Aloe Hall, in the Cape Town International Convention Centre.

“This is a great opportunity for us to share our approach on scaling with a broader group in an important forum, to show people what we have and get feedback to improve further,” says Thiele. “I’m really looking forward to this event!”

RTB is applying the science to scaling to ensure that agricultural innovations have the greatest possible impact. Photo H.Rutherford/CIP


More details on the symposium are available here.
Learn more about RTB’s work on scaling and participation at the event here

Bad news for Fusarium wilt: “Breeding Better Bananas” means business

Hi pests and diseases, it’s your nasty cousin Fusarium. I’ve got an update for you from banana fields and scientists’ labs in Arusha, Tanzania. Its rather mixed news, I am afraid, as the humans seem to be making some progress.

First, some good news. Coffee prices and profits are down so many farmers are interested to switch to bananas. That could mean a bigger area to attack. And once I can get into the soil in their fields, I can stay for at least sixty years. Isn’t it great?

Fortunately, most farmers still aren’t aware that I am spreading in their irrigation water and even on their pruning tools. And climate change seems to be giving me a helping hand, because farmers are irrigating more since it has been so dry. I’m on the move, and you don’t have to take my word for it. According to Akida Meya, of The Nelson Mandela African Institution of Science and Technology (NM-AIST). “Since last year Fusarium wilt is making a breakthrough in higher lands on Mount Meru above 1,200 meters where it hadn’t gotten a foothold before.”

I’m really making progress in Arusha, where I’m knocking out the  Mchare banana variety, which humans in the East African highlands like for cooking with meat in stews and other dishes. One real sign of my success is that Mchare is getting scarcer and more expensive in local markets. Isn’t that a fabulous indicator of my progress?

Look at this photo below of a farmer’s field of Mchare that I just about wiped out; and I did it right under the scientists’ noses, near the Tanzanian Coffee Research Institute (TaCRI)! That farmer won’t harvest anything from those plants.

Mchare banana plants with dead leaves have been wiped out by Fusarium wilt near TaCRI

Mzee Mbora Ulotu, who works with the team at TaCRI, practices traditional and now disappearing coffee-banana intercrop on his own farm


It’s not all good news though. Some of the farmers have been tipped off by the scientists and extension people. Mzee Ramadhan Rashid Kimaro of Masama village is one of this dangerous group. He realized that I was attacking his Mchare bananas and changed tactics. Four years ago, with help from those pesky scientists at the Ministry of Agriculture Training Institute in Horti-Tengeru, he got new plants from tissue culture including Paz, Grand Naine and Williams (dessert bananas also used for cooking). Thanks to those new varieties, careful residue management, manure and managing sucker replacement to keep his banana plants nicely in rows, he is getting very good bunches and making money from bananas. All quite upsetting for me, although luckily more than 85% of farmers haven’t caught on. Fortunately, there isn’t any network of community level nurseries where farmers can get clean planting materials of resistant varieties, although a few have gone to Crop Biosciences in Arusha or Kilimorgano in Dar es Salaam. So far there aren’t any resistant varieties of Mchare, so I am going to continue to feast on those.

Scientists admire Mzee Ramadhan Rashid Kimaro’s big bunch of Paz bananas

Mzee Kimaro has good mat management and carefully uses crop residues and manure


There is a rather troublesome group of scientists from the International Institute of Tropical Agriculture (IITA) working with NM-AIST that has me worried. They’ve got some great shared labs and a rather impressive group of scientists who have me in their sights. They are trying to nail me down with an excellent tissue culture, molecular and pathology facility which speeds up their access to plants for experiments and eventually new varieties.

Magdalena Kiurugo manages the tissue culture lab at NM-AIST

Fusarium cultured in petri dishes at NM-AIST

Worse yet, IITA and Bioversity International have teamed up in a new project called ‘Improvement of banana for smallholder farmers in the Great Lakes Region of Africa,’’ under the logo “Breeding Better Bananas – BBB,” which is supported by the Bill and Melinda Gates Foundation. It’s part of the CGIAR Research Program on Roots Tubers and Bananas, which is chasing down  us pests and diseases. BBB has brought in 21 NARITA hybrids which are good for cooking, although they are Matoke rather than Mchare types. Noel Madalla and his colleagues at Bioversity International have planted these out in Moshi at TaCRI in what they call a “mother trial”. With the aid of clever software on a tablet, they are collecting massive amounts of data about me and my cousin Sigatoka (a.k.a. black leaf streak), as well as plant growth and yields. I heard Madalla say that “Next year we are going to have farmers select from the mother trial those which taste and look the best to test in their own fields in ‘baby trials’.”

I am getting worried that this BBB group may find a resistant NARITA which farmers like and the women say is good for cooking. Then I’ll be in trouble!

Part of the Breeding Better Bananas team

Using a tablet with FieldTask app to enter plant bar code before data entry in the mother trial

Banana breeders have already made crosses of Mchare varieties with wild relatives with resistance to my disease: Fusarium wilt. Fortunately, it’s going to be a challenge for them to develop resistant varieties that farmers will grow, because the humans are very fussy and like great tasting bananas. That should take them a while, or so I hope, though scientists at IITA and Horti-Tengeru are trying to speed things up. They have a mapping population made by crossing a resistant wild banana relative with a susceptible one, so they have a large number of genetically different plants, some with resistance genes, to do detective work on. They put 50 g of millet seeds infected with me, Fusarium, in each pot with a banana plant to see if I can infect the plant. Then those crafty scientists are going to collect DNA from all these plants and send them off for genotyping to BTI, in the USA, to find which nasty genes stop me from infecting banana plants. Their goal is to identify markers for Fusarium wilt resistance which the breeders can use to stop me in my tracks. Mohamed Mpina of IITA predicts that “We should have the markers in a couple of years and that will really speed up our breeding, which takes so long because we have to get back to a seedless variety after making our crosses”.

Mohamed Mpina should have markers from this mapping population at Horti-Tengeru inoculated with Fusarium wilt

Hassan Mduma’s research is throwing light on how nematodes in these pots aggravate the effects of Fusarium wilt

As you might imagine, I’m getting a little nervous, but I haven’t given up. I’m hoping climate change will lend me a hand. Nevertheless, those guys at BBB have me worried. It should take them a few more years to give me serious trouble, though, so in the meanwhile, I’ll keep up my destruction. Will send another letter to the pests and diseases family next year.


Text and photos by Graham Thiele, Director, RTB

RTB scientists at the forefront of developing technologies to help farmers cope with climate change

Climate change is creating new challenges for smallholders that research for development organizations are striving to address. Photo N.Palmer/CIAT


As government representatives negotiate ways to strengthen the international response to global warming at the United Nations Climate Change Conference COP23, in Bonn, Germany, scientists around the world are working on technologies to help farmers produce food and generate income in a warming world.

The CGIAR Research Program on Roots, Tubers and Bananas (RTB) is coordinating varied efforts to meet the challenges of climate change that include an initiative to assess the risks of crop pests and diseases under future climate scenarios, and help government institutions prepare for them: innovations to accelerate the breeding of resilient root, tuber and banana varieties; and deployment of climate-smart technologies such as the ‘Triple S’ seed system for sweetpotato, which will help farmers produce planting material as dry seasons become longer.

Root and tuber crops have the potential to play a more important role in food security, but more resilient varieties will be needed as climate change advances. Cassava, for example, is drought tolerant, but climate change is causing increasingly erratic rainfall, which affects the starch content of cassava roots, since sudden rain before harvest can result in new foliage growth and reduced starch content in roots. Cassava breeders at the International Center for Tropical Agriculture (CIAT) are thus developing varieties with more stable starch yields under variable rainfall. 

As banana is sensitive to drought, scientists at the International Institute of Tropical Agriculture (IITA) are concentrating on breeding drought-tolerant varieties.  However, as IITA banana breeder Dr. Rony Swennen explains, bananas don’t wilt, so protocols to screen effectively for drought responses are being developed. 

Sweetpotato is also relatively drought tolerant, and because its storage roots develop underground, they often survive tropical storms, providing vital food after winds or flooding destroy other crops. Scientists at the International Potato Center (CIP) sweetpotato breeding program in Mozambique, led by Dr. Maria Andrade, have developed 15 drought-tolerant, pro-vitamin A, orange-fleshed sweetpotato (OFSP) varieties that were released in 2011 and an additional four varieties released in 2016. These varieties now account for one-third of the sweetpotato produced in Mozambique, and some of them are also being grown in Madagascar, Ivory Coast and Abu Dhabi, or are being used as parents for breeding programs in other countries.

CIP potato breeders have also developed varieties that tolerate drought, heat and soil salinity, some of which have been released in Africa, Asia and South America. These include the heat- and drought-tolerant variety Sarnav, which is being grown in three regions of Uzbekistan, and the salt- and heat-tolerant variety BARI Alu-72, which is being grown in coastal lowland areas of Bangladesh that suffer seawater intrusion. One variety developed and released in Peru under the name Tacna was later released in China under the name Jizhangshu 8, and by 2008, it was being grown on over 20,000 hectares there.

Potato and sweetpotato were included among the stress-tolerant crop varieties to counter climate change in a working paper entitled 10 best bet innovations for adaption in agriculture: A supplement to the UNFCCC National Adaption Plan Technical Guidelines. A project of the CGIAR Research Program on Climate Change, Agriculture and Food Security (CCAFS), that paper was written to support governments in the elaboration of their National Adaption Plans.

Dr. Jan Low, a Principal Scientist at CIP, contributed to that working paper and participated in two COP23 side events organized by CCAFS. She explains that in addition to breeding for tolerance to drought and other environmental stresses, CIP breeders are developing potato and sweetpotato varieties that mature early. Since 2009, 40 early-maturing sweetpotato varieties, which can be harvested within 90-120 days after planting, have been released in sub-Saharan Africa. Early maturity allows farmers to better avoid high stress environments and provides them with more flexibility to fit the crop into optimal growing seasons. Low adds that another top priority for CIP breeders is that potato and sweetpotato varieties have high levels of micronutrients.

Though cassava is a drought-tolerant crop, breeders are developing more resilient varieties to help farmers cope with climate change. Photo H.Homes/RTB


“The idea is to combine varieties that can perform well under stress, in drought conditions, and at the same time provide excellent nutrition, particularly vitamin A,” says Low. “We need to ensure the quality of the food as well as the ability to produce food under difficult conditions.”

In order to help root, tuber and banana breeding programs speed up the development of climate-smart varieties, RTB has made a significant investment in genomic research, which has included the DNA sequencing and field tests of thousands of plant accessions. Scientists at RTB centers and partner organizations are using the resulting data to identify genetic markers associated with specific crop traits – such as heat or drought tolerance – that can be used to accelerate the breeding process. Researchers at IITA, for example, are studying gene expression changes in response to drought in banana, in order to understand the genetic basis of drought tolerance. RTB genomic research is being complemented by field research to ensure that new varieties being developed have the traits that men, women and youth want.

CIP sweetpotato breeders have developed 15 drought-tolerant varieties that now account for one third of the sweetpotatoes grown in Mozambique. Photo M.Andrade/CIP


“Given the pressing nature of climate change, I think significantly increased investment in breeding will be required to meet the challenges,” observes Dr. Graham Thiele, Director of RTB. “There are indications that progress is possible and some encouraging examples in the RTB portfolio, but overall, tackling climate change needs a step change in longer term funding. We need to have targets for improving traits which take on board future climates. To achieve these targets, breeding programs need to become more focused and product and demand driven, if they are going to rise to the challenge. One important development is support and funding for the Excellence in Breeding Platform, with which RTB is actively partnering.”


Sweetpotato puree makes nutritious, inexpensive bread while creating a new market for farmers


By Michael Friedmann, RTB Science Officer

At the Organi Ltd factory, in Western Province, Kenya, a grinder was churning out ribbons of an orangey puree, which workers quickly wrapped and sealed in plastic bags under vacuum.  I was tempted to stick my finger in and grab some, as it looked quite tasty, but we were covered in protective clothing so as not to contaminate the product. No fingers allowed! 

I was visiting the factory with Tawanda Muzhingi and Penina Muoki, research scientists with the International Potato Center (CIP) who had taken the time to show me the value chain for orange-fleshed sweetpotato (OFSP) in Western Kenya.  A CIP-led project has been promoting the development of products made from OFSP to create and expand markets for sweetpotato root producers, and the vine growers who provide them with planting material. 

All this as part of an effort to combat Vitamin A deficiency (VAD) a critical health problem in sub-Saharan Africa (SSA) that can lead to blindness and stunting in young children.  Campaigns to encourage the production and consumption of OFSP by smallholder families have been shown to be an effective way to combat VAD.  However, people in Africa have traditionally eaten white or yellow-fleshed sweetpotatoes, which aren’t rich in Vitamin A, and they don’t readily shift to the more nutritious orange-fleshed types. 

By promoting products made from OFSP that can be consumed year-round, also in the cities, CIP can strengthen the campaign against VAD while providing more stable incomes for farmers, and the vine growers who provide them with planting material.  Many options have been tried, and the sweetpotato puree appears to be economical and versatile as an ingredient for many food products.  Indeed, it can replace between 20 and 45% of the wheat flour in baked products such as bread and biscuits.

OFSP roots are pureed and vacuum packed at the Organi Ltd factory. Photo C. Bukania/CIP-SSA

The Organi Ltd factory has a capacity to process 200 kilograms of roots per hour, and produce 1 ton of puree a day. The company buys about 20 tons of OFSP roots per month from local smallholder farmers, most of who are women, whereas a number of youths are employed at the factory for grading, washing, cleaning, peeling, cooking, and mashing OFSP roots into puree. The puree is vacuum packed in 3- to 5-kg bags and shipped to Tuskys, the largest supermarket chain in Kenya.  

Tuskys’ central bakery produces more than 3,000 loaves of OFSP bread per day, as well as buns and muffins, for sale at its 23 stores in the greater Nairobi area.  Consumer studies conducted in Tuskys supermarkets found that sweetpotato bread is well liked, and since the puree costs less than wheat flour, it is actually sold at a lower price. The bread is also a good source of beta-carotene, which our bodies convert into vitamin A. Lab analysis conducted by CIP and the Biosciences eastern and central Africa-International Livestock Research Institute (BecA-ILRI) Hub determined that two slices of the OFSP bread provide the equivalent of 10 percent of the daily vitamin A requirement for children.

“Orange fleshed sweetpotato puree is a versatile ingredient in culinary and food processing applications and will revolutionize the way to eat root and tuber crops in Africa,” says Muzhingi, a specialist in food science and nutrition-sensitive agriculture.


OFSP bread has become so popular that the Organi Ltd factory now bakes and sells loaves. Photo M. Friedmann/RTB

OFSP bread has become so popular that Organi Ltd set up some ovens in the puree factory and now bakes its own bread to sell locally. It smelled good, looked very nice, and when I gave a loaf a gentle squeeze, it felt just right!

According to Muzhingi, Organi Ltd purchases OFSP from smallholder farmers for almost double the price on the local markets, and since most of those suppliers are women, the income helps cover the day-to-day household needs of some very needy families. “The OFSP puree value chain is a win-win for everyone and we are looking forward to scaling out and scaling up in the region,” he says.

The puree factory needs a steady supply of OFSP roots, so CIP works to ensure that local farmers can produce enough. This requires an ample supply of virus-free OFSP vines for planting material, because sweetpotato viruses can significantly lower yield, especially when infected vines are replanted. Consequently, the project trains some farmers to become decentralized vine multipliers, and the Kenya Plant Health Inspectorate Services provides them with virus-free starter material derived from tissue culture plantlets that have been screened for viruses. Vine producers are essential for Organi Ltd to be able to scale up production, or for other puree producers to come on board, as demand for OFSP baked goods grows. 

I was thus happy to visit a vine multiplier named Teresa at her farm in Homa Bay County, near Kisumu, in Western Kenya, which is a major sweetpotato production area. She showed us the two small net tunnels that she grows planting material in, in order to protect the vines from the whiteflies that spread sweetpotato viruses.  Teresa and her husband became vine multipliers and learned to use the net tunnels thanks to CIP’s Scaling up Sweetpotato through Agriculture and Nutrition (SUSTAIN) project, and they produce planting material of the Kabode and Vitaa OFSP varieties, which were bred at NARO-Uganda in collaboration with CIP.

Teresa was a gracious host, and she explained the various challenges that she and other OFSP vine multipliers face. She mentioned that many farmers still prefer the white and yellow local varieties, which are freely exchanged among farmers, unlike the OFSP vines that farmers have to purchase from vine multipliers. As part of efforts to promote the consumption of OFSP, CIP and partners work with rural health clinics to educate pregnant women and mothers about the value of eating OFSP and feeding it to their children, while linking them to vine multipliers such as Teresa, who can supply them with virus-free planting materials.

Teresa and other vine multipliers grow OFSP planting material in net tunnels. Photo M. Friedmann/RTB

“I have to encourage the farmers I meet at the health facilities to plant OFSP,” Teresa explains. “Other farmers come to my farm and ask me why I plant OFSP and where they can find a market for it. I am happy to introduce them to people at Organi Ltd.” 

As demand for OFSP baked goods grows, more farmers should start growing those varieties, which will increase demand for virus-free planting material. And the more farmers that grow OFSP in a community, the greater that likelihood that the children and women of child-bearing ages who benefit most from that nutritious crop will eat it regularly.  

By educating people about the benefits of eating OFSP while building demand for the crop in both urban and rural areas, CIP aims to reduce the incidence of VAD and improve farmer incomes.

Six steps to speed up climate-smart breeding in roots, tubers and bananas

Research centers and their partners have made good progress toward harnessing the potential of roots, tubers and bananas to improve food security, nutrition and smallholder incomes, but scientists are concerned that impacts of climate change could undercut many of those gains in the coming years.

Photo: N.Palmer/CIAT

In response to this threat, a team of scientists working with the CGIAR Research Program on Roots Tubers and Bananas (RTB) collaborated on a paper that underscores the urgency of building greater climate resilience into crops as global weather and climate patterns shift in a warming world. Published in Open Agriculture, the paper, entitled ‘Roots, Tubers and Bananas: Planning for Climate Resilience, outlines six steps needed to enhance the planning, breeding, dissemination and management of climate-smart varieties.

Over the last decade, “the urgency has really increased,” notes Dr. Graham Thiele, Director of RTB and lead author of the paper. “It’s being driven by the growing awareness of the reality of climate change, as well as a growing body of evidence about its potential impacts on agriculture, especially in some of the most vulnerable environments in Africa. Resilience is becoming much more center stage in our research planning.”

Thiele adds that while a gap remains between the sheer scope of the problem and investments into research needed to address it, there are many positive developments, such as more targeted climate-change models that will help researchers plan more effectively for a changing climate in the years ahead. 

RTB is actively collaborating in this area with the CGIAR Research Program on Climate Change, Agriculture and Food Security  (CCAFS). Dr Philip Thornton of CCAFS noted: “Decision support tools are going to play a vital role helping to set priorities and targeting research and scaling of climate smart options.” 

“Crops are sensitive to changes in temperature and erratic rainfall patterns, so we need more locally detailed models to be able to understand the overall impacts of climate change and the adaptations needed [to respond to them],” observes Dr. Michael Friedmann, science officer at RTB.  He notes that RTB supports research in East Africa that combines data from farm surveys, weather stations and laboratory experiments to create risk maps and models to predict the threats posed by specific crop pests and diseases under future climate scenarios.

Predictions of potato late blight severity in sub-Saharan Africa using a metamodel                                         Left: current late blight severity; Right: late blight severity predicted by 2050 (source: Sparks et al. 2014)

“Most studies looking into the effects of climate change on food security have only focused on crop yields and may be under-estimating the magnitude of the link between climate change and food security,” said Dr. Dorcus Gemenet, molecular breeder and abiotic stress geneticist with the International Potato Center’s (CIP) Genomics and Crop Improvement group.

She explains that while drought and heat stress are the main threats to crop yield under climate change, crop breeders also need to address related factors such as irregular rainfall and increased pressure from pests and diseases as they work to develop climate-smart varieties. She adds that while improving yield is the top priority for breeders, they also need to understand how climate change may affect crop quality or shelf life, which is an especially important issue for roots, tubers and bananas.

Gemenet is working with scientists at North Carolina State University and other partners to identify DNA markers in sweetpotato that breeders can use to speed up the development of improved varieties. Over the past decade, CIP has worked with sweetpotato breeders in Africa to accelerate the breeding process, cutting the time it takes to cross, select, field test, and release a new variety from eight years to four. Gemenet and colleagues hope that the genomic tools they are currently developing will significantly further reduce in the time it takes to develop new sweetpotato varieties.

Changes in establishment and potential distribution (ERI) and abundance (GI) of the sweet potato weevil, Cylas puncticollis, according to model predictions from 2000 and to 2050. An ERI>0.95 is associated with potential permanent establishment of the pest (source: Okonya et al. 2016).

“If the breeding process cannot be made more rapid, then we won’t be able to develop the varieties that farmers need to adapt to climate change,” says Gemenet, adding that the challenge is both urgent and personal for her.

“Apart from being a scientist, I am the daughter of a peasant farmer in Kenya,” she says. “It is devastating to see a farmer who has lost his crops to drought.”

Gemenet explains that while accelerating the development of climate-smart varieties, breeders need to ensure that they have the traits that men and women want, so that they are widely adopted. RTB is prioritizing this goal though its coordination of the CGIAR Gender and Breeding Initiative.

“There is already pressure to produce enough food now, and it is daunting to think about the future, but we need to prepare for the future,” she says.

Gemenet explains that as pressing as the challenges created by climate change are, she is encouraged by the pace of advances in technology and knowledge sharing that scientists can take advantage of. She adds that CIP and the other RTB centers have already accomplished a great deal toward making root, tuber and banana production more resilient, which she and her colleagues can build upon.

As Thiele observes: “Climate smart breeding means we need to keep doing what we are already doing. We just need to do it faster, better and smarter.”

By Amy Rogers Nazarov and David Dudenhoefer

Understanding gender norms to improve the effectiveness of interventions

By Anne Rietveld, Bioversity International scientist and RTB gender focal point

It was April 2014, and we’d reserved two vans to take RTB researchers to Mukono village, in Central Uganda, to test the methodology for GENNOVATE: which addresses how gender norms and agency influence men, women and youth to adopt agricultural innovations. However, due a mix up, the two vans delivered by the rental agency were too small to hold the entire group, so I had to borrow our office’s enormous, black, four-wheel drive vehicle.

After dropping off the researchers, I drove to the town’s marketplace to buy some bananas for snack time. Although we were just a few hours away from Kampala, the capital, I attracted quite a lot of attention as I maneuvered the vehicle through the narrow streets around the market, as bystanders pointed at me and shouted. One man came up to my window and said, apologetically: “They’ve never seen a woman drive a car, and such a big car, they just cannot believe it”.

I often remembered this incident as I read through the GENNOVATE data. When women discussed changes in their perceptions of what women are capable of, for instance, some mentioned that just seeing other women in non-traditional roles was eye opening. Although that didn’t usually mean that gender norms would change overnight, it did strengthen my belief that our presence in rural areas can influence perceptions on many fronts beyond the technologies we test or promote. It’s an encouraging thought for those who, like me, are interested in designing pathways to contribute to ‘gender transformation’ for more equality.

RTB researchers learned to use the GENNOVATE methodology in Mukono, Uganda in April 2014. Photo A. Rietveld/Bioversity International

A CGIAR-wide gender research initiative

The RTB researchers who were trained that day went on to conduct GENNOVATE case studies in Uganda, Malawi and Burundi in the months that followed. Each GENNOVATE case study refers to a single community in which a set of standardized qualitative tools is used to collect data from men and women. Other RTB researchers later completed case studies in Colombia, Bangladesh and the Philippines.

GENNOVATE was conceived at a 2013 meeting of the CGIAR gender network, in Montpellier, France. One of the presenters, Patti Petesh, discussed her research for the 2012 World Bank report ‘On Norms and Agency’, which catalyzed a discussion on qualitative research as the key for understanding the role of gender norms – the social rules that prescribe men’s and women’s roles and behavior – and agency, which refers to one’s capacity to act, in agricultural innovation and technology adoption processes. Petesh was later hired to design the methodology guide for the seven qualitative research tools used for GENNOVATE.

Researchers from across the CGIAR have used that methodology to conduct a total of 137 case studies in 26 countries over the past few years. A series of different products has begun to emerge from that research, one of which is Gender in agricultural change: towards more inclusive innovation in farming communities. This report, which covers 24 GENNOVATE case studies conducted in ten countries, was written by researchers from the CGIAR Research Program on Roots, Tubers and Bananas (RTB) in collaboration with staff from the former CGIAR Research Program on Integrated Systems for the Humid Tropics (Humidtropics). The report was edited by Gordon Prain, the former head of the Social and Health Sciences Global Program at the International Potato Center (CIP).

According to Prain, RTB promoted both gender integration research and strategic gender research from the start, and has invested considerable resources in gender integration research, which focuses on interdisciplinary collaboration between gender scientists and biophysical scientists. But the GENNOVATE research, he says: “Delves into the underlying issues of normative constraints and power distribution between men and women.”

Prain explains that, while it may not have an immediate pay-off in terms of research outcomes, GENNOVATE is nonetheless important. “What is exciting about this research, and why it is important for RTB, is that it represents the ‘up-stream’ component of gender integration research, the understanding of social processes involving the relations between women and men, which will impact the uptake of research outputs. We need this understanding in order to more effectively integrate gender into technology innovation,” He says.

In addition to the new report and other products resulting from GENNOVATE, the initiative has provided very valuable experiences for the RTB social and gender scientists and other researchers who participated in it. GENNOVATE provided an opportunity to do in-depth social research across the CGIAR, with younger and more experienced researchers working together, and thereby created a platform for capacity building. For example, entire teams of field staff benefitted from training in qualitative data collection methods, whereas most of GENNOVATE’s principal investigators received training in the use of NVIVO, a software package for qualitative data-analysis. Thus GENNOVATE has not only marked the first CGIAR-wide, in-depth social study, it has equipped RTB researchers to produce better and more relevant research in the future.

Understanding social norms and their affect on women’s ability to act can help RTB and partners make their promotion of agricultural innovations more effective. Photo A. Rietveld/Bioversity International

A surprising focus on roots, tubers and bananas at the Sugarcane Research Institute of Tanzania

By Graham Thiele, Director, CGIAR Research Program on Roots, Tubers and Bananas (RTB)

Judging by the name, the Sugarcane Research Institute of Tanzania is not the first place one would expect to find research on roots, tubers and bananas. However, as members of RTB’s Independent Steering Committee discovered on our recent visit, the principle focus of research at the institute is on cassava and sweetpotato, for which they have the mandate for Eastern Agro-ecological Zone of Tanzania.

Dr. Kiddo Mtunda, Director of the Sugarcane Research Institute (SRI), explained that whilst it’s important to keep “sugar cane” in the institute’s name because of support from the sugar industry, in practice much of the work at the station is on roots and tubers, which began in 1989. Research work on sugarcane started in 1971 and is done at the sugarcane plantations closer to the growers.

A partner of RTB, the institute has a dedicated ‘Root and Tuber Crops Research Programme’, which is wide ranging, including participatory varietal selection, production of breeder and pre-basic seed and post-harvest value added. Dr. James Legg, Plant Health Specialist at the International Institute of Tropical Agriculture (IITA) and leader of RTB’s flagship project on ‘Resilient Crops’, explained that there is a very close collaboration between researchers at SRI and both International Potato Center (CIP) and IITA scientists.

During the RTB Independent Steering Committee’s visit, which followed the committee’s annual meeting, members were fortunate to visit labs and fields at Kibaha. The first stop was the Nematology lab, where Dr. Nessie Luambano explained that she had completed her PhD in plant nematology and was currently conducting a project on the diversity of three banana nematodes species and susceptibility to nematodes of different banana varieties from major banana growing areas of Tanzania.

Many staff at SRI wear several hats! Dr. Luambano also works with sweetpotato and she explained that one of the activities underway is to generate revenue and create a self-sustaining business at SRI with pre-basic seed.

She went on to explain that clean material, from Kenya Plant Health Inspectorate Service, was multiplied with support from the Sweet Potato Action for Security and Health in Africa project (with CIP) and distributed as pre-basic seed Importantly, the Tanzania Official Seed Certification Institute (TOSCI) inspects the pre-basic seed including virus testing at the Mikocheni Agricultural Research Institute laboratory. SRI sells the pre-basic seed on to multipliers. It’s encouraging that demand for this is increasing.

Dr. Luambano also said that SRI is carrying out a full costing of seed production with support from CIP scientists as part of a CIP project on building seed businesses with the public sector.

SRI also works on cassava seed systems with a rapid multiplication method using two node cuttings supported by USAID. There has been a shared learning across different crops with IITA and CIP collaboration promoted by RTB’s research cluster on seed. As Dr. Simon Heck, leader of RTB’s flagship project on ‘Nutritious food and added value’ noted, “We all dance together on this!”

The next port of call was to see research carried out by Dr Esther Masumba. Dr Masumba is collaborating with the DSMZ Plant Virus Department in Germany with five genotypes from Latin America that reputedly have immunity to cassava brown streak disease (CBSD). Dr Masumba is looking for quantitative trait loci (QTLs) for immunity, and a next stage in the research will involve a crossing block for cassava breeding in Dodoma District, Tanzania.

Then the ISC got back on the bus to visit cassava trials of SRI at the Chambezi substation. This is a high disease pressure area for cassava with problems of green mite, cassava mosaic disease (CMD) and CBSD.

We saw materials from the “New Cassava varieties and Clean seed to Combat CBSD and CMD” (5CP) project – a regional initiative which brought together five African countries.  Now concluded, 5CP was a unique project where the best five varieties/clones for CBSD resistance were pooled from each participating country, plus three controls, then all 28 were shared with all countries through tissue culture. Altogether evaluation trials like these are being conducted at 33 sites in the five countries.

Varities from 5CP. Photo G.Thiele/RTB

We then saw a cassava seed degeneration trial. This included a) Kikombe, a variety susceptible to CBSD and b) Kiroba, a variety resistant to CBSD but susceptible to CMD. The trial compared planting in two rainy seasons, one with shorter periods of rainfall with many whitefly present (which transmit the virus), and the second with longer periods of rainfall and less insects.

So far, the trial has run for four seasons during the long rains and three seasons in short rains. In the shorter season, CBSD had reached 30-60% incidence. Dr. Legg explained that previously the difference between seasons had not been well understood, and as cassava is mostly grown in the short rainy season, the trial concluded that it would be advantageous to switch to farming during the long rainy season. A simple solution that could make a big difference for small-scale farmers! The degeneration trials are part of a suite of degeneration studies with RTB supported by modelling by the University of Florida.

This was an excellent visit and the ISC committee members were very interested to learn more about the research being done by our partners at SRI. Dr. Rupert Best, the ISC chair commented “although the name highlights sugarcane, this was a perfect visit from an RTB perspective, showcasing collaboration with an important partner and spanning most of our crops.” Dr. Barbara Wells, Director General of CIP added that “we were hugely impressed to see so many dynamic women scientists coming to the fore.”

New tools improve smallholder access to quality planting material

From the RTB 2016 Annual Report

Because root, tuber and banana crops are propagated clonally—by planting tubers, suckers, stalks, or vine cuttings—they present common challenges for farmers that include low multiplication rates, perishable planting material and low yield as a result of seed degeneration. Government agencies and non-government organizations have developed seed systems to disseminate improved varieties and high-quality planting material (commonly referred to as ‘seed’), but only a small fraction of smallholders have access to those formal seed systems.

To increase farmer access to quality planting material and improve yields, centers under the CGIAR Research Program on Roots, Tubers and Bananas (RTB) have collaborated on cross-crop research to develop tools for improving seed systems and seed degeneration management.

RTB researchers developed a multi-stakeholder, seed systems framework and used it to analyze 13 formal and informal seed systems for five RTB crops in Africa and Latin America, extracting lessons that can be applied across crops and contexts. The International Potato Center (CIP) then used the framework for a scoping study of potato seed systems in Karnataka and Maharashtra, India, identifying bottlenecks that prevent more farmers from gaining access to quality seed potatoes. RTB researchers will make the framework more gender responsive and use it to assess more seed systems in 2017.

Potato farmers in Ecuador. Photo: CIP

Seed degeneration – the transmission and accumulation of pests or pathogens from one seed cycle to the next via planting material – is a major cause of yield loss, and is consequently a priority for RTB. Researchers conducted literature reviews on seed degeneration, developed a theoretical seed degeneration model, and used it to assess the effectiveness of different approaches to managing seed degeneration. This resulted in the development of an integrated seed health strategy, which combines the use of disease-resistant varieties with on-farm management practices such as roguing (removing plants with disease symptoms), positive selection (choosing healthy planting material in-field for the next planting cycle), and strategic replacement of seed with disease-free material.

To better understand the dynamics of seed degeneration, researchers have conducted field trials in different agro-ecologies of eight African and South American countries. The trials used popular varieties of banana, cassava, potato, sweetpotato and yam infected with 11 pathogens and spanned multiple cropping cycles over several years. They included evaluations of common on-farm management practices, generation of data on pathogens and vectors, and the effects of weather, varietal resistance levels, seed management, and other agronomic practices on seed degeneration.

The resulting data are being used to develop crop-specific seed degeneration models that scientists can use to predict how varieties will perform in specific agro-ecologies under determined disease pressures, weather conditions and management strategies. They will be used to develop management performance maps and decision support tools that research and extension agencies, and seed producers can use to identify the best options for managing degeneration.

The field research has shed new light on pathogen dynamics and management strategies. For example, potato research in Ecuador demonstrated that reversion (naturally occurring reduction of pathogen incidence within a seed lot) takes place at higher altitudes. Researchers used impact network analysis to study planting material movement in informal sweetpotato seed systems in northern Uganda, completing in silico simulations of the introduction of a novel virus to identify nodes within those distribution networks of importance for disease sampling and mitigation.

“There is a bias against informal seed systems, and most interventions try to create seed systems from scratch,” said CIP seed specialist Jorge Andrade, who coordinates the RTB seed systems research. “It is important to understand the dynamics of informal seed systems and farmer demand for planting material before designing any intervention.”

Andrade explained that RTB is developing a toolbox of analytical and diagnostic methodologies that government agencies, national agricultural research systems, NGOs, and donors can use to improve the design and execution of seed-system interventions and the management of seed degeneration.