Tag: Maize Lethal Necrosis

Three major commercial maize seed exporting countries in southern Africa found free from maize lethal necrosis

Written by on November 25, 2016. Posted in News.

brenda_2 — Maimouna Abass, a plant health inspector at Zambia Agriculture Research Institute collects leave samples to test for MCMV in a practical session during the MLN surveillance and diagnostic workshop held in Harare, Zimbabwe. Photo: D. Hodson/CIMMYT

NAIROBI, Kenya (CIMMYT) – Three major commercial maize-growing and seed exporting countries in southern Africa were found to be so far free from the deadly maize lethal necrosis (MLN) disease. MLN surveillance efforts undertaken by national plant protection organizations (NPPOs) in Malawi, Zambia and Zimbabwe in 2016 have so far revealed no incidence of MLN, including the most important causative agent, maize chlorotic mottle virus (MCMV).

The three countries export an estimated 7,000 metric tons of maize seed to Angola, Botswana, Democratic Republic of Congo, Ethiopia, Kenya, Malawi, Mozambique, Rwanda, Swaziland and Tanzania for commercial cultivation by millions of smallholder farmers whose households rely on maize as a staple food.

MLN surveys were conducted as part of ongoing efforts through a project on MLN Diagnostics and Management, funded by U.S. Department for International Development (USAID) East Africa Mission, to strengthen the capacity of NPPOs on surveillance and diagnostics. A total of 12 officers were equipped with knowledge on modern sampling and diagnostics techniques to test plants and seed lots for MLN causing viruses; this was done through a training workshop held in Harare, Zimbabwe on March 3 and 4, 2016 facilitated by scientists working with the International Maize and Wheat Improvement Center (CIMMYT).

The NPPO teams from Malawi, Zambia and Zimbabwe then undertook surveys of farmers’ and commercial maize seed production fields, including testing (through MCMV immunostrips) for possible presence of the virus.

“When CIMMYT called the first stakeholders awareness meeting we realised we needed to do this surveillance as soon as possible to ascertain MLN status in the country – and so the training was very important and extremely useful,” said Maimouna Abass, a plant health inspector at Zambia Agriculture Research Institute (ZARI). “The fact that we went to the field and successfully conducted the surveys using the MLN diagnostics and sampling techniques learnt was great.”

Abass and three colleagues who participated in the training, trained 10 other inspectors who took part in the surveillance work.

The results from farmers’ fields, commercial seed production fields and agri-seed dealers, showed negative results for the presence of MCMV and MLN. The MLN surveillance techniques and protocols used across all the three countries were similar, making it possible to effectively compare the results.

“The harmonization of the protocols, across the teams from Malawi and Zambia, was important for me, since this meant that the three countries were able to do the same surveillance using the same protocols and applying the same design across all the countries,” said Nhamo Mudada, chief research officer from the Plant Quarantine Station in Zimbabwe.

Participants recieve instructions from L.M Suresh, a maize pathologist at CIMMYT, during the MLN surveillance and diagnostic workshop. Photo: D.Hodson/CIMMYT

Although the MLN disease has not been detected in the southern Africa region, the risk of incidence still remains high through various means, including insect vectors, contaminated seed, and cross-border grain transfers. Therefore, continued caution and stringent surveillance, monitoring and diagnostic measures are required to prevent the possible incidence and spread of MLN into the non-endemic countries.

Further surveillance work will be conducted in 2017, so that each team can cover other targeted areas within their respective countries. MLN surveillance using harmonized protocols will also be undertaken in the MLN-endemic countries, namely Ethiopia, Kenya, Rwanda, Tanzania and Uganda. Through systematic surveillance efforts, NPPOs, seed companies and policymakers can clearly understand the prevalence of MLN in specific areas in an endemic country for targeted management. Also, seed companies will be able to target production of commercial seed in MLN-free areas.

As this work progresses, B. M. Prasanna, director of the CGIAR Research Program on MAIZE and CIMMYT’s Global Maize Program as well as Leader for the MLN Diagnostics and Management Project, emphasized the need to intensively deploy MLN-tolerant and resistant varieties, not only in the MLN-endemic countries in eastern Africa, but also in the non-endemic countries in sub-Saharan Africa.

“We have about 22 new, high-yielding, MLN-tolerant or resistant hybridsthat are presently under national performance trials in Kenya, Tanzania and Uganda. We actively encourage seed companies operating in southern Africa to take up promising pre-commercial hybrids with MLN tolerance or resistance from CIMMYT, for release, scale up and deployment to the farmers,” Prasanna said. “Diagnostics and surveillance have to go hand in hand with deployment of new improved varieties that can effectively respond to the MLN challenge.”

In the East African countries of Kenya, Tanzania and Uganda, seed companies have already released MLN-tolerant varieties. While one hybrid is already being commercialized in Uganda, three more are expected to reach farmers in Kenya and Tanzania from 2017.

“There is also now a very urgent need to deploy MLN resistant varieties in Rwanda and Ethiopia. We need to convey this message to the government and seed companies and work closely to get the seed of MLN resistant varieties to the farmers as soon as possible,” Prasanna added.

The MLN diagnostics and management project, which is funded by the U.S. Department for International Development (USAID), supports work aimed at preventing the spread of MCMV from MLN-endemic to non-endemic areas in sub-Saharan Africa. USAID also supports the commercial seed sector and phytosanitary systems in targeted countries (Ethiopia, Kenya, Malawi, Rwanda, Tanzania, Uganda, Zambia and Zimbabwe), in the production of MCMV-free commercial seed, and promotes the use of clean hybrid seed by the farmers.

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.

MLN diagnostics and management in Africa through multi-institutional synergies

Written by on May 9, 2015. Posted in News.

Maize Lethal Necrosis (MLN) disease has continued to wreak havoc on maize production in East Africa since it was first reported in Kenya in 2011, and since then reported in the Democratic Republic of the Congo, Ethiopia, Rwanda, Tanzania, South Sudan and Uganda. The disease, caused by a combination of the Maize Chlorotic Mottle Virus (MCMV) and Sugarcane Mosaic Virus (SCMV), causes irreversible damage that kills maize plants before they can grow and yield grain. MLN pathogens can be transmitted not only by insect vectors but also through contaminated seed. The epidemic is exacerbated by lack of MLN-resistant maize varieties and year round cultivation of maize in many areas in eastern Africa, enabling the build-up of virus inoculum and allowing transmission via insect vectors. For this reason, CIMMYT scientists Monica Mezzalama, Biswanath Das, and B.M. Prasanna have developed a brochure “MLN Pathogen Diagnosis, MLN-free Seed Production and Safe Exchange to Non-Endemic Countries” for providing important information on these key areas to stakeholders, especially seed companies and regulatory agencies operating in both MLN-affected as well as MLN non-endemic countries.

“MLN is an increasing regional threat to food security in sub-Saharan Africa, and must be tackled with concerted effort from all actors in order to safeguard the maize seed sector and protect the livelihoods of smallholder farmers,” said Prasanna. The brochure proposes several key steps to curb the spread of MLN, through MLN diagnostics, production of MLN-free seed, and safe exchange to MLN-endemic countries. The brochure also advises on appropriate agronomic practices that can prevent disease incidence in seed production fields.

An International Conference on “MLN Diagnostics and Management in Africa” will be organized jointly by AGRA (Alliance for Green Revolution in Africa) and CIMMYT during 12-14 May in Nairobi, Kenya, in order to review the present status of MLN incidence and impacts in sub-Saharan Africa (SSA), controlling seed transmission of MLN, managing seed production in MLN-endemic countries, creating awareness about MLN diagnostic protocols, and identifying ways to strengthen MLN diagnostics capacity in SSA, among other topics.

Stepping up the fight against maize lethal necrosis in Eastern Africa

Written by on August 1, 2013. Posted in News.

MLN-Eastern-Africa1 “I can now identify with accuracy plants affected with maize lethal necrotic disease,” stated Regina Tende, PhD student attached to CIMMYT, after attending the CIMMYT-Kenya Agricultural Research Institute (KARI) “Identification and Management of Maize Lethal Necrosis” workshop in Narok, Kenya, during 30 June-3 July 2013. This was not the case a few weeks ago when Tende, who is also a senior research officer at KARI-Katumani, received leaf samples from a farmer for maize lethal necrosis (MLN) verification.

Tende is one of many scientists and technicians who experienced difficulty in differentiating MLN from other diseases or abiotic stresses with similar symptoms. According to Stephen Mugo, CIMMYT Global Maize Program (GMP) principal scientist and organizer of the workshop, this difficulty encouraged CIMMYT and KARI to organize this event to raise awareness about MLN among scientists, technicians, and skilled field staff; provide training on MLN diagnosis especially at field nurseries, trials, and seed production fields; train on MLN severity scoring to improve the quality of data generation in screening trials; and introduce MLN management in field screening sites to scientists, technicians, and skilled staff. The workshop brought together over 80 scientists and technicians from CIMMYT, KARI, and other national agricultural research systems (NARS) partners from Tanzania, Uganda, Rwanda, and Zimbabwe.

“It is important that all the people on the ground, particularly the technicians who interact daily with the plants and supervise research activities at the stations, understand the disease, are able to systematically scout for it, and have the ability to spot it out from similar symptomatic diseases and conditions like nutrient deficiency,” stated GMP director B.M. Prasanna.

Proper and timely identification of the MLN disease, which is a pre-requisite for effective control, is not easy. CIMMYT maize breeder Biswanath Das explains: “First of all, the disease is caused by a combination of two viruses, Maize chlorotic mottle virus (MCMV) and Sugarcane mosaic virus (SCMV). Secondly, its symptoms –severe mottling of leaves, dead heart, stunted growth (shortened internode distance), leaf necrosis, sterility, poor seed set, shriveled seeds– are not always unique to MLN but could be due to other fungal diseases and abiotic conditions.” The training workshop was one of CIMMYT/KARI initiatives to combat the disease threatening all the gains made so far in maize breeding. “With nearly 99% of the commercial maize varieties so far released in Kenya being susceptible to MLN, it is important that institutions like CIMMYT and KARI, in strong collaboration with the seed sector, develop and deploy MLN disease resistant varieties in an accelerated manner,” stated Prasanna. One of the key initiatives in this fight is the establishment of a centralized MLN screening facility under artificial inoculation for Eastern Africa at the KARI Livestock Research Farm in Naivasha. Plans are also underway to establish a network of MLN testing sites (under natural disease pressure) in the region to evaluate promising materials from artificial inoculation trials in Naivasha. The state of the art maize doubled haploid (DH) facility currently under construction in Kiboko will also play a crucial role in accelerating MLN resistant germplasm development. “The DH technology, in combination with molecular markers, can help reduce by half the time taken for developing MLN resistant versions of existing elite susceptible lines,” stated Prasanna.

MLN-Eastern-Africa2 During his opening speech, Joseph Ng’etich, deputy director of Crop Protection, Ministry of Agriculture, noted that about 26,000 hectares of maize in Kenya were affected in 2012, resulting in an estimated loss of 56,730 tons, valued at approximately US$ 23.5 million. Seed producers also lost significant acreages of pre-basic seed in 2012: Agriseed lost 10 acres in Narok; Kenya Seed lost 75; and Monsanto 20 at Migtyo farm in Baringo, according to Dickson Ligeyo, KARI senior research officer and head of Maize Working Group in Kenya.

While this loss represents only 1.7%, Ligeyo assured everyone that Kenya is not taking any chances and has come up with a raft of measures and recommendations: farmers in areas where rainfall is all year round or maize is produced under irrigation are advised to plant maize only once a year; local quarantine has been enforced and farmers are to remove all infected materials from the fields and stop all movement of green maize from affected to non-affected areas; seed companies must ensure that seeds are treated with appropriate seed dressers at recommended rates, they must also promote good agricultural practices, crop diversification, and rotation with non-cereal crops.

Throughout the workshop, participants learned about theoretical aspects of MLN, such as the disease dynamics, management of MLN trials and nurseries, and identification of germplasm for resistance to MLN. They also participated in practical sessions on artificial inoculation, and identification and scoring. Several CIMMYT scientists played an active role in organizing the workshop, including breeders Stephen Mugo, Biswanath Das, Yoseph Beyene, and Lewis Machida; entomologist Tadele Tefera; and seed systems specialist Mosisa Regasa. They were accompanied by KARI scientist Bramwel Wanjala, KEPHIS regulatory officer Florence Munguti, and NARS maize research leaders Claver Ngaboyisonga (Rwanda), Dickson Ligeyo (Kenya), Julius Serumaga (Uganda), and Kheri Kitenge (Tanzania). During his closing remarks, KARI Food Crops program officer Raphael Ngigi, on behalf of KARI director, urged participants to rigorously implement what they had learnt during the workshop in their respective countries or Kenya regions to help combat MLN at both research farms and farmers’ fields.

Commenting on the usefulness of the workshop, technical officer at KARI-Embu Fred Manyara stated: “I will no longer say I do not know or I am not sure, when confronted by a farmer’s question on MLN.”

Promising CIMMYT maize inbreds and pre-commercial hybrids identified against maize lethal necrosis (MLN)

Written by on June 14, 2013. Posted in News.

The maize lethal necrosis (MLN) disease first appeared in Kenya’s Rift Valley in 2011 and quickly spread to other parts of Kenya, as well as to Uganda and Tanzania. Caused by a synergistic interplay of maize chlorotic mottle virus (MCMV) and any of the cereal viruses in the family, Potyviridae, such as Sugarcane mosaic virus (SCMV), Maize dwarf mosaic virus (MDMV), or Wheat streak mosaic virus (WSMV), MLN can cause total crop loss if not controlled effectively.

A regional workshop on MLN and the control strategies was organized by CIMMYT and KARI during February 12-14, 2013 in Nairobi, which was attended by some 70 scientists, seed company breeders and managers, and representatives of ministries of agriculture and regulatory authorities in Kenya, Uganda, Tanzania, and the USA. The Workshop led to identification of important action points steps for effectively controlling the disease.

CIMMYT scientists have been working closely with virology experts from USDA-ARS and Kenya Agricultural Research Institute (KARI) to develop suitable protocols for testing the responses of maize germplasm against MLN, and to identify promising inbred lines and hybrids with resistance to MLN. During the 2012-2013 crop season, the CIMMYT-KARI team undertook extensive screening of inbred lines, pre-commercial and commercial hybrids in Naivasha and Narok in Kenya, under high natural disease pressure and artificial inoculation, respectively.

A trial featuring 119 commercial maize varieties (released in Kenya) under artificial inoculation during 2012-2013 revealed that as many as 117 varieties were susceptible to MLN. Another set of trials including 335 elite inbred lines, 366 pre-commercial hybrids and 7 commercial hybrids (as checks) under MLN artificial inoculation in Narok, and another set of trials comprising 350 elite inbred lines and 135 pre-commercial hybrids under natural disease pressure in Naivasha, led to identification of some promising CIMMYT inbred lines as well as pre-commercial hybrids showing resistance or moderate resistance. These results offer considerable hope to combat, through breeding efforts, the deadly MLN disease that has severely affected maize harvests and discouraged farmers from growing maize in eastern Africa.

Notes on trial results

The details of the promising CIMMYT elite inbred lines and pre-commercial hybrids against MLN are presented in Table 1 and Table 2, respectively. The results presented in Table 1 are based on evaluation of CIMMYT inbred lines in four independent trials, two under artificial inoculation (Narok) and two under natural disease pressure (Naivasha) during 2012-2013. In each trial, entries were replicated (minimum two), and MLN severity scores (on a 1-5 scale basis) were recorded three or more times during the crop cycle, from the vegetative to the reproductive stage. The highest average MLN severity score (max. MLN score), recorded at any stage during the trial, is presented as representative of a given entry.

The data must be critically assessed and cautiously used by stakeholders and partners. More weight should be given to data from artificially inoculated trials, since trials under natural disease pressure are more liable to ‘disease escapes’ and identification of false positives. Caution must be exercised when using specific lines identified as potentially resistant (R) or moderately resistant (MR), especially when classification is based on data from only one trial (even under artificial inoculation). Please note that in such cases, the responses of the lines need to be validated by CIMMYT through further trials.

CIMMYT is working closely with both public and private sector partners to significantly expand the MLN evaluation network capacity in eastern Africa, and will continue the intensive efforts to identify/develop and deliver new sources of resistance to MLN.

For further information on:
MLN research-for-development efforts undertaken by CIMMYT, please contact: Dr BM Prasanna, Director, Global Maize Program, CIMMYT, Nairobi, Kenya; Email: b.m.prasanna@cgiar.org.
Availability of seed material of the promising lines and pre-commercial hybrids, please contact: Dr Mosisa Regasa (m.regasa@cgiar.org) if your institution is based in eastern Africa, or Dr James Gethi (j.gethi@cgiar.org) if your institution is based in southern Africa or outside eastern and southern Africa.

Additional resources

UPDATE: Promising CIMMYT maize inbreds and pre-commercial hybrids identified against maize lethal necrosis (MLN) in eastern Africa
Maize lethal necrosis (MLN) disease in Kenya and Tanzania: Facts and actions (Download )
KARI-CIMMYT maize lethal necrosis (MLN) screeing facility (1.43 MB)
Maize lethal necrosis: Scientists and key stakeholders discuss strategies as the battle continues

Videos

MLN: A farmer’s plea

Maize lethal necrosis disease: A new challenge
for maize scientists in eastern Africa

Media coverage

Deadly maize disease resurfaces in N. Rift. Business Daily, 31 May 2013.

Fresh viral maize disease worries farmers. Daily Nation, 31 May 2013.

Alert out in Coast over maize disease. Daily Nation, 31 May 2013.

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.