Tag: MCMV

Researchers and visitors listen to explanations during a tour of infected maize fields at the MLN screening facility in Naivasha, Kenya. (Photo: CIMMYT)

Fast-tracked adoption of second-generation resistant maize varieties key to managing maize lethal necrosis in Africa

Written by Rodrigo Ordóñez on January 19, 2021. Posted in Features.

Scientists are calling for accelerated adoption of new hybrid maize varieties with resistance to maize lethal necrosis (MLN) disease in sub-Saharan Africa. In combination with recommended integrated pest management practices, adopting these new varieties is an important step towards safeguarding smallholder farmers against this devastating viral disease.

A new publication in Virus Research shows that these second-generation MLN-resistant hybrids developed by the International Maize and Wheat Improvement Center (CIMMYT) offer better yields and increased resilience against MLN and other stresses. The report warns that the disease remains a key threat to food security in eastern Africa and that, should containment efforts slacken, it could yet spread to new regions in sub-Saharan Africa.

The publication was co-authored by researchers at the International Maize and Wheat Improvement Center (CIMMYT), Kenya Agricultural and Livestock Research Organization (KALRO), the Alliance for a Green Revolution in Africa (AGRA), the African Agricultural Technology Foundation (AATF) and Aarhus University in Denmark.

CIMMYT technician Janet Kimunye (right) shows visitors a plant with MLN symptoms at the MLN screening facility in Naivasha, Kenya. (Photo: CIMMYT)

Stemming the panic

The first reported outbreak of MLN in Bomet County, Kenya in 2011 threw the maize sector into a panic. The disease caused up to 100% yield loss. Nearly all elite commercial maize varieties on the market at the time were susceptible, whether under natural of artificial conditions. Since 2012, CIMMYT, in partnership with KALRO, national plant protection organizations and commercial seed companies, has led multi-stakeholder, multi-disciplinary efforts to curb MLN’s spread across sub-Saharan Africa. Other partners in this endeavor include the International Institute of Tropical Agriculture (IITA), non-government organizations such as AGRA and AATF, and advanced research institutions in the United States and Europe.

In 2013 CIMMYT established an MLN screening facility in Naivasha. Researchers developed an MLN-severity scale, ranging from 1 to 9, to compare varieties’ resistance or susceptibility to the disease. A score of 1 represents a highly resistant variety with no visible symptoms of the disease, while a score of 9 signifies extreme susceptibility. Trials at this facility demonstrated that some of CIMMYT’s pre-commercial hybrids exhibited moderate MLN-tolerance, with a score of 5 on the MLN-severity scale. CIMMYT then provided seed and detailed information to partners for evaluation under accelerated National Performance Trials (NPTs) for varietal release and commercialization in Kenya, Tanzania and Uganda.

Between 2013 and 2014, four CIMMYT-derived MLN-tolerant hybrid varieties were released by public and private sector partners in East Africa. With an average MLN severity score of 5-6, these varieties outperformed commercial MLN-sensitive hybrids, which averaged MLN severity scores above 7. Later, CIMMYT breeders developed second-generation MLN-resistant hybrids with MLN severity scores of 3–4. These second-generation hybrids were evaluated under national performance trials. This led to the release of several hybrids, especially in Kenya, over the course of a five-year period starting in 2013. They were earmarked for commercialization in East Africa beginning in 2020.

Maize Lethal Necrosis (MLN) sensitive and resistant hybrid demo plots in Naivasha’s quarantine & screening facility (Photo: KIPENZ/CIMMYT)

Widespread adoption critical

The last known outbreak of MLN was reported in 2014 in Ethiopia, marking an important break in the virus’s spread across the continent. Up to that point, the virus had affected the Democratic Republic of the Congo, Kenya, Rwanda, Tanzania and Uganda. However, much remains to be done to minimize the possibility of future outbreaks.

“Due to its complex and multi-faceted nature, effectively combating the incidence, spread and adverse effects of MLN in Africa requires vigorous and well-coordinated efforts by multiple institutions,” said B.M. Prasanna, primary author of the report and director of the Global Maize Program at CIMMYT and of the CGIAR Research Program on Maize (MAIZE). Prasanna also warns that most commercial maize varieties being cultivated in eastern Africa are still MLN-susceptible. They also serve as “reservoirs” for MLN-causing viruses, especially the maize chlorotic mottle virus (MCMV), which combines with other viruses from the Potyviridae family to cause MLN.

“This is why it is very important to adopt an integrated disease management approach, which encompasses extensive adoption of improved MLN-resistant maize varieties, especially second-generation, not just in MLN-prevalent countries but also in the non-endemic ones in sub-Saharan Africa,” Prasanna noted.

The report outlines other important prevention and control measures including: the production and exchange of “clean” commercial maize seed with no contamination by MLN-causing viruses; avoiding maize monocultures and continuous maize cropping; practicing maize crop rotation with compatible crops, especially legumes, which do not serve as hosts for MCMV; and continued MLN disease monitoring and surveillance.

L.M. Suresh (center-right), Maize Pathologist at CIMMYT and Head of the MLN Screening Facility, facilitates a training on MLN with national partners. (Photo: CIMMYT)

Noteworthy wins

In addition to the development of MLN-resistant varieties, the fight against MLN has delivered important wins for both farmers and their families and for seed companies. In the early years of the outbreak, most local and regional seed companies did not understand the disease well enough to produce MLN-pathogen free seed. Since then, CIMMYT and its partners developed standard operating procedures and checklists for MLN pathogen-free seed production along the seed value chain. Today over 30 seed companies in Ethiopia, Kenya, Uganda, Rwanda and Tanzania are implementing these protocols on a voluntary basis.

“MLN represents a good example where a successful, large-scale surveillance system for an emerging transboundary disease has been developed as part of a rapid response mechanism led by a CGIAR center,” Prasanna said.

Yet, he noted, significant effort and resources are still required to keep the maize fields of endemic countries free of MLN-causing viruses. Sustaining these efforts is critical to the “food security, income and livelihoods of resource-poor smallholder farmers.

To keep up with the disease’s changing dynamics, CIMMYT and its partners are moving ahead with novel techniques to achieve MLN resistance more quickly and cheaply. Some of these innovative techniques include genomic selection, molecular markers, marker-assisted backcrossing, and gene editing. These techniques will be instrumental in developing elite hybrids equipped not only to resist MLN but also to tolerate rapidly changing climatic conditions.

Read the full report on Virus Research:
Maize lethal necrosis (MLN): Efforts toward containing the spread and impact of a devastating transboundary disease in sub-Saharan Africa

Cover photo: Researchers and visitors listen to explanations during a tour of infected maize fields at the MLN screening facility in Naivasha, Kenya. (Photo: CIMMYT)

A worker at the Naivasha MLN research station conducts a mock inoculation (Photo: Joshua Masinde/CIMMYT)

Battling devastating viral diseases, also in plants

Written by Jennifer Johnson on May 28, 2020. Posted in Features.

When a maize lethal necrosis (MLN) outbreak happened in Kenya in 2011, scientists knew they needed to act fast. This viral disease, new to Kenya, was decimating maize fields. Within a few years, the viral disease spread rapidly in eastern Africa, through both insect vectors and contaminated seeds. If the virus were to spread into southern or West Africa, it would spell disaster for the smallholder farmers across the continent who depended on maize as a staple crop and for their family’s income and livelihoods.

The International Maize and Wheat Improvement Center (CIMMYT) and its partners immediately took action to impose a strict seed quarantine and restrict the movement of seed between eastern Africa and other regions in Africa. In addition, they worked intensively on developing and disseminating improved maize cultivars with tolerance or resistance to MLN, undertook extensive surveillance efforts, and sensitized partners on the importance of producing and commercializing MLN-free seed.

Due to these efforts, in the last nine years MLN has not been reported in sub-Saharan Africa outside of eastern Africa.

On the occasion of a recent publication on Virus Research about how MLN was contained, we interviewed B.M. Prasanna, director of the Global Maize Program at CIMMYT and the CGIAR Research Program on Maize (MAIZE), to discuss the MLN success story, the global COVID-19 crisis, and the similarities in the challenge to tackle plant and human viral diseases.

B.M. Prasanna, Director of the Global Maize Program at CIMMYT and the CGIAR Research Program on Maize (MAIZE). (Photo: Alfonso Cortés/CIMMYT)

What were some of the extreme measures CIMMYT had to take to stop the spread of MLN?

The first step that we had to take in the fight against MLN was to rigorously analyze seed for any possible contamination with MLN-causing viruses and restrict movement of seed from eastern Africa to southern Africa.

The second most important step was to sensitize the national partners and the commercial seed sector about the danger of seed contamination with MLN-causing viruses, and how seed contamination can lead to the proliferation or spread of the disease.

The third important step was to build a new MLN quarantine facility in Zimbabwe, in partnership with the National Plant Quarantine Institute. Only when that quarantine facility was functional in 2017, we reinitiated transfer of research material from CIMMYT’s breeding hub in Kenya to CIMMYT in Zimbabwe. Only when the materials were certified to be MLN-free both in Kenya and Zimbabwe, through plant-by-plant analysis using immunodiagnostic kits, the seed was multiplied and further distributed to partners. So, the principle of containment and effective management is extremely important, whether it is a plant viral disease or a human viral disease.

We must note here that in terms of scale and intensity, as well as global effects and implications, any plant disease, including MLN, cannot be compared with a pandemic like COVID-19, which has affected every aspect of our lives.

How do you think the COVID-19 pandemic is going to impact our food systems?

We are indeed in a grim situation. The pandemic will undoubtedly have a serious effect on food security.

Many countries which do not have enough food reserves or those where the food systems are vulnerable to shocks like this are suffering. The people’s capacity to procure inputs for agriculture, including seed, is going to be affected too, as the markets are affected. This is really a serious situation that we all should be concerned about. The CGIAR has an important role to play, in terms of working closely with national partners and mitigating the impact of COVID-19 on agriculture.

We should be particularly worried about farmers, especially smallholder farmers, who are quite vulnerable to the ongoing challenge. Even without COVID-19, agriculture in many developing countries worldwide has been already under distress. Small and marginal farmers were often unable to find a market for their produce and earn sufficient income to support their families. Their livelihoods are fragile, and vulnerable to climate change and volatile market prices. The ongoing COVID-19 crisis is unfortunately compounding the crisis.

What lessons can agricultural research learn from this pandemic?

What do these pandemics or epidemics teach us? They remind us that systems need to be in place to prevent the proliferation of such diseases, whether it is plant diseases or animal diseases or human diseases. No country can be considered completely safe, and such diseases do not discriminate between a developed and a developing country, or the rich and the poor.

The second most important lesson is emergency preparedness. Whenever such devastating transboundary viral diseases show up, how quickly the country can respond — containing that infected area and not allowing the disease to spread, and then mitigating the damage systematically and quickly — is key. This is not the first time that a disease like MLN has emerged. There could be more serious viral or fungal diseases that could emerge in the future due to various reasons, including changing climates, international trade, movement of human beings, air currents, etc. There are multiple ways that diseases can go across continents, across countries within a continent, and within countries. Therefore, the key is how well we can capacitate the national systems to be able to proactively prevent, detect, and intervene very fast.

Another big lesson here for agricultural systems is that a problem that happens in some other continent cannot be ignored because you work in a different continent. What COVID-19 shows is that the world is far more connected than we think.

CIMMYT team members check for traces of the maize chlorotic mottle virus (MCMV) in maize plants during a visit to the MLN screening facility in Naivasha, Kenya. (Photo: Joshua Masinde/CIMMYT)

For you, what is the biggest takeaway from the MLN success story?

I won’t say it is still a complete success. Through intensive partnerships and efforts, we were able to prevent the disease from devastating maize production in millions of smallholder farmers’ fields in sub-Saharan Africa. Since 2014, there has been no new country in Africa — outside eastern Africa — that has reported an outbreak of MLN. That, to me, is a tremendous success.

The work is still not over. The journey has to continue. And we still need to make sure that countries are continuously protected from devastating diseases like MLN. MLN is still not eradicated from eastern Africa. It may not be even possible to completely eradicate this disease, as the two viruses that together cause it can survive not just on maize but on multiple grasses. We can however contain the disease and limit its impact through continued efforts, like what we have done for the past 7 or 8 years. But if we lower our guard, there is a very high likelihood that the disease can still spread to other countries in sub-Saharan Africa, especially the major maize-growing countries in southern Africa or West Africa. Efforts need to continue. So, let us continue to maintain a high vigil to protect the smallholders in Africa from transboundary diseases like MLN.

Read the full article on Virus Research:
Maize lethal necrosis (MLN): Efforts toward containing the spread and impact of a devastating transboundary disease in sub-Saharan Africa

How a disease without borders was contained

Written by Rodrigo Ordóñez on November 25, 2019. Posted in Features.

It’s been eight years since maize lethal necrosis (MLN) was first reported on the African continent. When it appeared in Kenya’s Bomet County in 2011, a sense of panic swept across the maize sector. Experts quickly realized that all maize varieties on the market were susceptible to this viral disease, which could wipe out entire maize fields.

Spearheaded by the International Maize and Wheat Improvement Center (CIMMYT), a rapid regional response involving national agriculture research systems (NARS), national plant protection organizations and seed sector partners was set up. The response involved multiple approaches: rigorous surveillance, epidemiology research, disease management across the seed value chain, and screening and fast-tracking of the MLN-tolerant maize breeding program.

Now, CIMMYT and its partners are reflecting on the tremendous impact of transboundary coalition to contain the devastating disease.

“Country reports show there are now much less incidents of MLN in the region. We have effectively contained this disease as no new country in sub-Saharan Africa reported MLN since Ethiopia in 2014. This is a great achievement of an effective public private partnership,” noted B.M. Prasanna, Director of CIMMYT’s Global Maize Program and the CGIAR Research Program on Maize.

He was speaking at the closure workshop for the MLN Diagnostics and Management project and the MLN Epidemiology project on October 15-17, 2019, in Nairobi, Kenya. Experts from research, plant health and seed sector organizations from eastern and southern Africa reflected on the tremendous impact of the transboundary coalition to contain MLN across the region.

“The outbreak of the disease in Uganda in 2012 was a huge challenge as all the maize varieties and hybrids on the market were susceptible. With the support of CIMMYT and other partners in the national agriculture research systems, we got access to Bazooka, a high-yielding, drought- and MLN-tolerant maize variety that has helped in containing the disease,” said Godfrey Katwere, marketing manager for NASECO.

Until now, 19 MLN-tolerant and -resistant hybrids have been released, helping to keep the disease away from farmers’ fields and to stop its spillover to non-endemic countries in sub-Saharan Africa.

Science in action

The MLN screening facility, established in Naivasha in 2013, has been key to a better understanding of the disease and to setting up MLN hybrid tolerance and resistance breeding efforts. The facility, funded by the Bill & Melinda Gates Foundation and the Syngenta Foundation for Sustainable Agriculture, has supported public and private partners to screen over 200,000 germplasm with around 300,000 rows of maize.

State-of-the-art epidemiology research has been carried out to identify how the disease could be transmitted and the best diagnostics methods along the seed value chain.

MLN is caused by the combination of the maize chlorotic mottle virus (MCMV) and any of the viruses belonging to the Potyviridae family.

As part of the project, studies showed that moist soil had higher MCMV virus loads than dry soil. The studies — conducted by Benham Lockhart of University of Minnesota and Peg Redinbaugh, a professor at Ohio State University and Research Leader and Research Plant Molecular Geneticist at USDA — indicated that MCMV can stay active in runoff water, and helped in understanding how the disease is transmitted and how to define management protocols.

“Crop debris may also act as source of MCMV inoculum but for a limited period of up to two months,” said L.M. Suresh, CIMMYT Maize Pathologist, in reference to soil transmission studies conducted by CIMMYT. “A host-free period of two months is, therefore, recommended for effective management of MLN,” he noted.

Rapid and low-cost MLN-causing virus detection methods such as immunostrips and ELISA-based tests were adopted at scale.

“After optimizing the protocols for MLN viruses’ diagnosis suitable for African systems, we transferred these technologies to [national plant protection organizations] and seed companies, not just within the endemic countries but also to the non-endemic countries in southern and west Africa, through intensive trainings,” Prasanna explained. “We created a digital MLN surveillance tool under the Open Data Kit (ODK) app for NPPOs and other stakeholders to effectively carry out MLN surveillance on the ground. The survey information is captured in real time in farmers’ and seed production fields coupled with rapid immunostrips MLN tests,” he remarked.

According to Francis Mwatuni, Project Manager of the MLN Diagnostics and Management project, this proactive and collaborative surveillance network has been an important outcome that helped curb MLN from spreading to non-endemic regions. “In 2016, we only had 625 surveillance points. By 2019, the surveillance points in all the target countries stood at 2,442, which intensified the alertness on MLN presence and how to effectively deal with it,” Mwatuni said. In total, 7,800 surveillance points were covered during the project implementation period.

Over 100 commercial seed firms have also been trained on how to produce MLN-free seed to facilitate trade within the endemic nations and to ensure the disease is not transferred to the non-endemic countries via contaminated seeds.

Participants at the MLN projects closure workshop stand for a group photo. (Photo: Joshua Masinde/CIMMYT)

Sustaining the fight

Researchers continue to work to lessen MLN’s resurgence or new outbreaks. In 2018, incidents in all endemic countries, except Ethiopia, declined sharply. One suggested explanation for the upsurge in Ethiopia, especially in the northwestern region, was reduced use of pesticide for fall armyworm control, as compared to previous years where heavy application of these pesticides also wiped out MLN insect vectors, such as maize thrips and aphids.

At the end of the projects, partners urged for the scale-up of second-generation MLN-tolerant and -resistant varieties. They explained farmers would fully benefit from recent genetic gains of the new improved varieties and its protection against MLN.

“Despite the success registered, MLN is still a major disease requiring constant attention. We cannot rest as we redirect our energies at sustaining and building on the gains made,” said Beatrice Pallangyo, principal agricultural officer in Tanzania’s Ministry of Agriculture, Food Security and Cooperatives.

After the success containing MLN, stakeholders suggested the need to stay alert on other transboundary pests and diseases such as the tar spot complex, which could be a major threat to Africa’s food security in case of an outbreak.

Combating spread of MLN in Africa poses unique but surmountable challenges, seed health specialist says

Written by on November 14, 2016. Posted in Features.

Anne Wangui, a seed health technician at CIMMYT demonstrate DAS–ELISA method used for detecting MLN-causing viruses. B.Wawa/CIMMYT

NAIROBI, Kenya (CIMMYT) – The maize lethal necrosis (MLN) disease poses a major concern to researchers, seed companies and farmers in sub-Saharan Africa. The impact of MLN is massive in the affected countries, especially at the household level for smallholder farmers who can experience up to 100 percent yield loss.

Concerted regional efforts through a project funded by the U.S. Agency for International Development (USAID) over the past year have helped in prioritizing and targeting efforts to stop the spread of the disease from the endemic to the non-endemic countries in sub-Saharan Africa. The project target countries are Ethiopia, Kenya, Rwanda, Tanzania and Uganda (currently MLN endemic), while Malawi, Zambia and Zimbabwe are MLN non-endemic but important commercial maize seed producing countries where the project implemented extensive MLN surveillance efforts.

Determining exactly how the MLN causing viruses, which include maize chlorotic mottle virus (MCMV) and sugarcane mosaic virus, are transmitted in the field through insect-vectors, infected plants and seed lots, has made diagnosis a key element in the efforts to halt the spread of the disease. If the viruses, in particular MCMV, the major causative agent, are introduced into a new area through contaminated seed and infected plants and not diagnosed and destroyed immediately, MLN can spread rapidly. Insect vectors in the field can play a significant role in transmitting viruses to the neighboring healthy maize fields.

In order to manage MLN at a regional level, partners in the project are developing harmonized diagnostic protocols to test, detect and prevent its spread through available mitigation measures. These were highlighted during the MLN Diagnostics and Management Project Review and Planning Meeting held in October, 2016 in Nairobi.

Monica Mezzalama, head of the CIMMYT Seed Health Laboratory in Mexico and a plant pathologist, shared her views on MLN testing and diagnostic methods that can be adopted to test maize plants and seed lots in the following interview.

Q: What is the role of diagnostics in managing MLN in Africa?

A: The role of sensitive, reliable, reproducible, affordable and standardized diagnostic tools is fundamental to the management of MLN in Africa. Only with an appropriate diagnosis tool, we can effectively detect and prevent further dispersal of the disease to the non-endemic areas through seed.

Q: What is the progress for detecting MLN in seed lots?

A: At the moment, detection in seed lots is still a weak link in the MLN management chain, although detection methods are available, such as ELISA and several versions of PCR, which are serological and molecular based, respectively, for the detection of MLN viruses. Extracting the pathogen from seed is more difficult than extracting it from leaf tissue, making it more time consuming to obtain clear and reliable results. Additionally, scientists are on the verge of resolving the significant issue of “sampling intensity,” which refers to the proportion of the seed sampled from the presented seed lots.

Q: What are some of the practices CIMMYT has adopted to ensure MLN-free seed production across regional centers in Africa?

A: Since 2013, CIMMYT has implemented several effective measures to ensure healthy MLN-free seed production and exchange. An aggressive strategy against the disease has been adopted at the main maize breeding station at Kenya Agricultural Livestock and Research Organization in Kiboko, by introducing a maize-free period of two months annually on the station as well as in the surrounding areas in close interaction with the farming communities in the neighboring villages. All this was possible thanks to the great collaboration between KALRO staff, CIMMYT colleagues, and the local farmers. This action taken for two consecutive years reduced drastically the incidence of MLN infected plants. In addition, a very thoughtful sensitization campaign was carried out, explaining how to effectively apply insecticide to control vectors, how to avoid the spread of the pathogen from one field to another by advising workers to change their clothes and shoes after working in an infected field. Also, management of planting dates has been implemented to avoid peaks of vectors populations or physically avoiding the arrival of the insects by planting according to the wind stream direction. In Zimbabwe, CIMMYT has also invested significant resources by establishing an MLN Quarantine Facility at Mazowe, near Harare to enable safe exchange of MLN virus-free breeding materials in southern Africa.

Q: Based on your experience with various diagnostic tools, what options would work for Africa’s seed companies and regulatory agencies to help detect MLN-causing viruses?

A: For detection of MLN viruses in green leaf tissue, I think immunostrips, ELISA and PCR techniques work very well and they can be adopted according to the level of specialization of the operator, infrastructure and financial resources available. As far as detection in dry seed is concerned, I think that at the moment the ELISA technique is the most reliable and affordable. PCR methods are available, but still some improvement needs to be done in the extraction of the viral RNA from the seed matrix.

Q: What factors do the relevant actors need to consider in the process of harmonizing diagnostic protocols across MLN-endemic and non-endemic countries?

A: Harmonization of protocols and procedures are needed not only for MLN, but also for effective design and implementation of phytosanitary aspects related to the exchange of commercial seed and vegetative material across borders. Unfortunately, it is not an easy task because of the number of actors involved, including national plant protection organizations, seed companies, seed traders, farmers, and policy makers. Nevertheless, the most important factors that, in my opinion, should be taken into consideration for consensus on harmonized protocols and where the efforts should focus on are: avoid the spread of the disease from country to country, and from the endemic to non-endemic areas within the same country; implement a well-coordinated and integrated package of practices for effective management of MLN in the endemic countries; reduce as much as possible economic losses due to the restriction on seed exchange; implement serious and effective seed testing and field inspections of the seed multiplication plots to prevent the incidence of MLN and for timely detection and elimination of infected plants.

View Meeting presentations here

MLN Pathogen Diagnosis, MLN-free Seed Production and Safe Exchange to Non-Endemic Countries Brochure

Visit the MLN website for more information

The CIMMYT-led MLN Diagnostics and Management Project, funded by USAID East Africa Mission is coordinating the above work with objectives to: a) prevent the spread of MLN, especially Maize Chlorotic Mottle Virus (MCMV), from the MLN-endemic countries in eastern Africa to non-endemic countries in sub-Saharan Africa; b) support the commercial seed sector in the MLN-endemic countries in producing MCMV-free commercial seed and promote the use of clean hybrid seed by the farmers; and c) to establish and operate a MLN Phytosanitary Community of Practice in Africa, for sharing of learning, MLN diagnostic and surveillance protocols, and best management practices for MLN control in Africa.

Maize lethal necrosis: Scientists and key stakeholders discuss strategies as the battle continues

Written by on March 7, 2013. Posted in News.

A recently-emerged disease in Eastern Africa, maize lethal necrosis (MLN), remains a serious concern. A regional workshop on the disease and its management strategies was held during 12-14 February 2013 in Nairobi, Kenya. Organized by CIMMYT and the Kenya Agricultural Research Institute (KARI), the workshop brought together nearly 70 scientists, seed company breeders and managers, and representatives of ministries of agriculture and regulatory authorities in Kenya, Uganda, and Tanzania, as well as experts from the U.S.A.

The key objective of the meeting was to “establish a strong interface between research and regulatory institutions in Eastern Africa to effectively tackle the MLN challenge, including the ongoing efforts and further steps to identify and deploy disease-resistant germplasm, and to create a system that can ensure a constant flow of varieties,” explained B.M. Prasanna, CIMMYT Global Maize Program director. Prasanna highlighted the difficulties faced by the maize farming community from the disease, and emphasized the need to accelerate deployment of MLN resistant maize varieties and to generate necessary awareness among the relevant stakeholders on management strategies. “It is necessary to break the MLN disease cycle and tackle the problem from multiple perspectives,” added KARI director Ephraim Mukisira. He mentioned that besides partnering with CIMMYT on breeding for MLN resistant varieties, KARI will also be distributing seed of alternative crops to farmers in affected areas. “As a dairy farmer, I will be planting napier grass instead of maize this season,” noted Mukisira.

The first signs of a new disease appeared in 2011 and 2012 in the Rift Valley Province, Kenya. A team of CIMMYT and KARI scientists identified it as MLN, a disease caused by a double infection of the maize chlorotic mottle virus (MCMV) and the sugarcane mosaic virus (SCMV) and transmitted by insects. According to Godfrey Asea, plant breeder and head of the Cereals Program at the National Crops Resources Research Institute (NaCRRI), Kampala, MLN was also identified in Uganda. Furthermore, symptoms of MLN have been cited in Tanzania, said Kheri Kitenge, maize breeder at the Selian Agricultural Research Institute (SARI), Arusha.

Scientists, particularly breeders, have made significant progress in tackling the disease. Studies are already underway at two field sites (Naivasha and Narok) where responses of a wide array of inbred lines and pre-commercial hybrids are being evaluated under high natural disease pressure and artificial inoculation. Participants visited the Sunripe Farm in Naivasha, where they observed KARI-CIMMYT MLN trials under natural disease pressure. A trial under artificial inoculation in Naivasha featuring nearly 175 commercial maize varieties is showing high levels of susceptibility to MLN. Researchers remain hopeful as some of the elite inbred lines and pre-commercial hybrids developed under projects such as the Drought Tolerant Maize for Africa (DTMA) or Water Efficient Maize for Africa (WEMA) are showing resistance to the disease.

During the farm visit, KARI pathologist Anne Wangai and her team showed how to generate artificial inoculum for MCMV and SCMV, as well as the enzyme-linked immunosorbant assay (ELISA) based technique for pathogen diagnosis at the national agricultural research laboratories at the KARI campus. The participants observed an artificial inoculation of maize seedlings in the field, followed by a discussion on some of the major changes in maize seed demand resulting from MLN incidence. “The maize seed industry is under stress in Kenya due to the need to replace some popular but MLN-vulnerable varieties as soon as possible,” explained Evans Sikinyi, Seed Trade Association of Kenya (STAK) executive officer. All stakeholders agreed that the foremost priority is to identify and speed deployment of MLN resistant maize varieties. “We also have to enhance the diagnostic capacity in the labs and ensure there is a rapid response and surveillance on MLN,” added Esther Kimani, general manager of phytosanitary services at the Kenya Plant Health Inspectorate Service (KEPHIS).

In the concluding session of the workshop, stakeholders identified key research areas and discussed partnership opportunities.