|Dr. Claude M. Fauquet
Director Adjunct GCP21
CIAT, Apdo. Aereo 6713
|Dr. Luis Augusto Becerra López-Lavalle
Cassava Program Leader
CIAT, Km 17 Recta Cali-Palmira
Cali, Colombia (A.A. 6713)
Tel: +57 2 4450000 Ext. 3356
|Dr. Jonathan Newby
Cassava Program Regional Coordinator - Asia
Ban Nongviengkham, Vientiane, Lao PDR
|GCP21||Colombia||Dr. C. Fauquet|
|CIAT||Lao||Dr. J. Newby|
|CIAT||Colombia||Dr. L.A. Becerra|
|GDA||Cambodia||Mr. P. Op|
|KU||Thailand||Dr. E. Sarobol|
|AGI||Vietnam||Dr. L.H. Ham|
|PPC||Lao||Dr. P. Siriphonh|
SUMMARY: In 2016, the first report of cassava mosaic disease – CMD was published, reporting the unequivocal identification of the Sri Lankan cassava mosaic virus as responsible for CMD symptoms in the north east of Cambodia as early as 2015. Since that date, several surveys have been done in Cambodia, Vietnam and Thailand, and as of mid 2017, the disease was present in 5 provinces in Cambodia and one in Vietnam. There was not a single case reported in Thailand. In 2 years, the disease progressed from a single plantation in Rattanakiri Province to an estimated 4% of the surfaces cultivated in the whole region. Therefore, the impact is still very limited but growing quickly. The disease is transmitted in two ways: by the natural whitefly vector (Bemisia tabaci, Aleyrodidae) and by the cuttings, there is no transmission through the roots nor the seeds. There is an active stake business carried by the cassava traders between several provinces of Cambodia and between Cambodia and Vietnam or Thailand. Although there is clearly insect transmission happening, it is believed that currently the disease is mostly done through cuttings. Considering the importance of cassava in the region (>55 million tons / year and >10 billion dollars business) urgent action is needed to stop the spread and put CMD under control. In March 2018, a mission was carried by GCP21 and CIAT in the 4 countries: Cambodia, Laos, Vietnam and Thailand and there is a strong consensus to establish a regional task force to control CMD and a unique plan of control is required. To this effect GCP21 and CIAT are organizing a Regional Meeting aiming at establishing such unique plan of control of CMD in Cambodia.
OF THE MEETING:
To elaborate, in writings, a unique plan of control of CMD, agreed by a large group of members of the 4 countries (Cambodia, Lao PDR, Vietnam and Thailand) and by members of international organizations.
Location: Phnom Penh
Duration: 1 day presentations + 1 day discussions +2 days for writing the plan
Tentative Dates: September 17-22, 2018
Countries participant: Cambodia, Thailand, Vietnam, and Lao PDR
Participants: SATREPS, CIAT, FAO, GIZ, IITA, TTDI, KU…; scientists, and plant protection and extension service officers from each country
International Donors Representatives: IFAD, UNDP, ACIAR, FAO, GIZ, AFD, EU…
Objective: Production of an agreed single regional control plan for 5 years
Proposed International Plan for CMD control in South-East Asia:
It is now well established that a virus disease is spreading in the South-East Asia (SEA) region, at least in Cambodia and also in Vietnam. The overall level of contamination is not very clear, the virus isolated has been identified as the Sri-Lankan Cassava Mosaic virus (SLCMV), and whiteflies (Bemisia tabaci) are present on cassava although in low populations. The epidemic is well established at present time in several provinces in Cambodia and all conditions are met for the epidemic to continue and invade the whole region. Considering the importance of the cassava crop in the region, it is clear that a well-coordinated plan to control or limit the spread is urgently required before the disease could reach catastrophic proportions. The planned meeting is aiming at writing a unique plan of control for the region and the present document aligns a set of information for a possible strategic plan to control CMD in SEA.
Elements to take in consideration for the regional meeting
Cassava Potential in the region
- The total production of cassava in the region is now above 56Mt/Y and this production continues to grow. The production went from 2.7mt in 1961 to reach 56mt in 2016 and increases at a pace of about 7.5% per year. The cassava production in the region has been dominated by Thailand, but has been tremendously boosted since 2000 and 2006 by the production of Vietnam and Cambodia respectively. The increase in production is the conjunction of the increase in surfaces planted (5%/y) and of the average yield in each country (1.5%/y).
- Cassava is the third crop production in the region after Sugarcane (117mt) and Rice (108mt).
- The total number of farmers involved in the region growing cassava is unknown but can be estimated between 10 and 15 million farmers. These are generally poor farmers, and cassava has significantly contributed to their well-being in recent years.
- The price of fresh cassava is variable in space and time but varied between $110 to $40 in the most recent years and therefore this total production represents between $2.5-$6b/Y of income for the farmers.
- Dry cassava is exported from the region, but starch is also produced, principally in Thailand and Vietnam, representing another income in the region estimated to $4-5b/Y.
- In addition, a number of peripheral businesses are benefitting from cassava production; transporters, processors, traders…
- Overall cassava represents an extremely important crop in the region and any impact of CMD on the regional production would significantly decrease the direct benefits to farmers and would impact the business or could even jeopardized a large segment of this cassava industry. After a phase of very low prices in the past 3 years, cassava is again in high demand with prices above $100 per ton of fresh roots. This high demand will boost planting and farmers will plant any cutting available, infected or not!
Potential CMD impact
Cassava viruses are very serious diseases and in Africa where these diseases are most prevalent today, more than one hundred years after the first description of CMD, the disease is still not under complete control and causes major losses every year. By all mean the CMD outbreak should be put under control the soonest possible in SEA before it will be impossible to control.
- Where is CMD in the world? until recently, CMD was only present in Africa and in the Indian subcontinent. CMD is the disease caused by ssDNA viruses belonging to the family Geminiviridae and transmitted by whiteflies and through the infected plant material. In Africa CMD is caused by 11 different species of geminiviruses out of which ACMV (African cassava mosaic virus) and EACMV (East African cassava mosaic virus) are the most important widespread and destructive viruses. In the Indian subcontinent, CMD is caused by two species of geminiviruses called ICMV (Indian cassava mosaic virus) and SLCMV (Sri Lankan cassava mosaic virus). All these viruses are endemic in each region, meaning that they were locally present in host reservoir plants and invaded cassava over time. No major importation was recorded in these continents. The CMD in south east Asia is attributed to SLCMV and presumably has been imported from the Indian Subcontinent.
- What is the impact of CMD viruses on cassava? Losses due to viral diseases, are very difficult to assess because it is the combination of the nature of the virus, the impact on each infected plant, of the frequency of infected plants in each field and on the mode of infection, not to mention agronomic practices and the environment. After decades of evaluation and work, the experts agreed that in Africa losses could be estimated to an overall 30% of the production.
- a 30% impact would cost billions to farmers, to the industry and to the countries; A 30% impact in south east Asia would represent huge losses, firstly for the farmers and secondly for the industry and all the people involved in its business. Farmers will have a net loss of production that can vary in space and time, but a 30% would be considered as a minimal loss in locations where the disease would be prevalent.
- domino effect with other issues such as price, competition… Furthermore, the number one problem for the industry is the amount of cassava to keep the factories running at 100%. A lack in production at the farmer level will automatically and immediately impact the industry. Other crops are competing with cassava, such as in central Vietnam where sugarcane, pepper, rubber and other crops are competing with cassava. The spread of CMD in the region could impact further its lack of competitivity, playing a domino effect in the production and putting the cassava processing industry at high risks.
Needs for designing a plan of action
Although CMD is present and visible in many plantations in the north east of Cambodia and one province in south Vietnam, It is currently unclear how much of the production is affected by CMD. In the same district from one plantation to the next we can record almost no disease to 100% infection, but in all fields visited at least one infected plant or more were spotted. The development of a proper plan of control will need to consider the spatial distribution and the frequency of the disease to define the appropriate level and the strategy for deployment of such plan.
- proper evaluation of the current spread in Cambodia and Vietnam (% and severity). It is therefore required to have a proper evaluation of the distribution and frequency of CMD in each district of each province. At least in those provinces where previous assessments have confirmed the presence of CMD. - proper identification of virus(es) involved; there has been only one molecular identification of the nature of the virus which was found to be SLCMV. However multiple identifications are needed to confirm that there is only one virus present in the infected region. A Proper control plan will take in consideration the virus diversity. There are several laboratories in the world capable of performing these molecular descriptions. - proper evaluation of whitefly populations and their nature; cassava viruses are transmitted in two ways; by the stakes and by whiteflies adapted to cassava. The recent epidemic of CMD and cassava brown streak disease (CBSD) in East Africa were triggered by the huge increase in whitefly populations that is now called “super-abundant whitefly”. It is not known why these whiteflies became super abundant on cassava in this part of the world but certainly the epidemics were the result of the whitefly population changes. In recent sporadic evaluations only fairly low whiteflies populations were observed (0 to 50 adults/plant), but these observations need to be confirmed by proper systematic evaluations performed at regular intervals during the growth cycle of cassava. Molecular identification of whitefly populations can be performed easily by several expert labs in the world.
Origin and nature of the disease
It is important to understand where the disease is coming from, in order to prevent further introduction/emergence and to design better policies to prevent introductions of more devastating diseases.
As far as we know the first reports of CMD in SEA are coming from the Ratanakiri province in north-east of Cambodia. The virus was molecularly identified as the Sri Lankan cassava mosaic virus, which is known to be present in India and Sri Lanka. However, that does not exclude the fact that this virus may have emerged spontaneously in Cambodia through a transfer of natural reservoirs, although it seems unlikely?
More molecular identifications from samples from the different infected regions of Cambodia and Vietnam, would confirm if only this virus is present or if more viruses can be identified. The molecular diversity of these isolates would also provide some information about the possibility of a local emergence.
This virus is part of the virus family Geminiviridae and they are known to be transmitted by the stakes coming from infected cassava mother plants and through the insect Bemisia tabaci. These viruses only infect cassava and are not dangerous for animals and humans. They usually impact the growth of the plant and have a negative impact on the yield. The impact level depends on the cassava variety, on the virus isolate and on the mode of infection. Infection though cuttings is the most damaging compared to infection through whiteflies. Huge losses up to 100% with similar viruses in Africa have been recorded.
If the virus has been imported through stakes, they must have been imported from the Indian subcontinent, pointing to the fact that regulations for introduction of plant material in SEA are very loose and should be reinforced to prevent further introductions.
- Immediate actions: Authorities of Cambodia and probably other neighbouring countries growing cassava should have a common position about CMD and the following immediate actions are proposed for consideration.
o Regional alliance of the 4 countries; Thailand, Cambodia, Vietnam, and Laos, should work a common plan of action to control CMD. Obviously cassava stakes are regularly exchanged between Vietnam and Cambodia and probably also with other countries. It will be a matter of time before virus-free countries will import the disease, so they should be involved ab initio in this plan. Viruses and whiteflies do not know about borders.
o International communication; after setting the regional alliance a common plan of communication should be aligned to let the world and the people involved into cassava business, know that a common plan will be developed in the region. Information about the progress of the plan and the results obtained should be shared regularly with the public. This unique plan may also attract the attention of donor agencies that may consider contributing more to a coordinated plan rather than country initiatives. This communication campaign should also reach farmers to encourage them to participate to the plan to control CMD.
- Short term actions: If the hypothesis that the main transmission of the virus through cuttings is correct, then there is a chance to control the disease by multiplying certified virus-free mother plants and distributing/selling certified virus-free stakes. Private enterprises could be enrolled in this program as long as certification would be put in place rapidly by the administration.
o Plan to propagate healthy plants to distribute in heavy infested region; it seems that Cambodia and Vietnam, have both a very well-organized extension service capable to reach every province and district of the country. Multiplication at the province level by extension services or enrolled companies could be done for the 2-3 most important varieties grown and virus-free material could be sent to every infected district, and subsequently provided to farmers. Distribution should be prioritized in districts were CMD is the most prevalent and later to districts with less infection.
o Opportunity to distribute new attractive varieties of cassava; new cassava varieties have been produced in Thailand that are more productive with higher starch content. This plan could take the opportunity to distribute virus-free new varieties to control CMD and improve cassava production at the same time. This could also be an incentive for farmers to buy these new seeds.
o It is believed that traders are playing an important role in the dissemination of the disease by moving infected cuttings over hundreds of km. It will be important to work with the traders to ensure their effective participation and to stop the spreading of infected material. Perhaps creating association so f traders and farmers to enrol them in the control plan.
o CTCRI in Kerala, India, has selected a number of varieties that are resistant to SLCMV. This material should be evaluated in several countries in the region for their capacity in term of yield, starch content, and of course for their CMD resistance. If satisfactory one or several of these varieties could be incorporated into the distribution of virus-free material.
o Survey of the effect of the plan; it is imperative that people involved in this plan verify the impact at the farm level performing regular assessments in many fields. Farmers should know about the plan and should be encouraged not to use infected plants for subsequent multiplication. This is of course only possible when the frequency of the disease is low (<5%), but many fields are in this situation. If rapid recontamination of certified virus-free material is observed, this would indicate that the whitefly transmission is more important than initially thought and this could possibly call for a revised plan of action.
o If the plan is positively controlling CMD, it should be extended to less infected districts; the plan should accommodate to needs and results. If a positive impact of the plan is recorded, then we should extend the plan to locations where the percentage of infected plants is very low (<1%), to prevent further spreading.
o The campaign should have a good communication plan to gain the complete participation of farmers, who can play a very important role in the control of CMD. Information about transmission through cuttings and whiteflies should be explained, rogueing of infected plants recommended and replacement of all cassava plants for heavy infections should be mandatory.
- Long term actions: On the long term, a contingency plan should be developed to introgress in appreciated varieties the geminivirus resistance gene such as CMD2. The effectiveness of CMD2 to control SLCM should be confirmed in laboratory and breeding program to this effect should be started soon. It will take several years to do this introgression, but if the control of CMD through virus-free material is ineffective, at least a genetic solution could be brought in the region in a fairly reasonable period of time.
o Introgression of CMD2 in major varieties cultivated in the region; CMD2 is a virus-resistance locus that has been shown in Africa to be capable of controlling geminiviruses very well. Depending on the nature of the virus, the resistance may not be complete but it is very efficient for some viruses. The drawback of such genetic method is that going through crosses, it will be difficult to create a variety having the same qualities as those of KU50 with CMD resistance, but it is worth trying. Crosses have already been done at Kasetsart University and could be tested in regions where CMD is present.
o Use of transgenic cassava resistance to SLCMV; it has been shown already that SLCMV can be controlled via genetic engineering using gene silencing in KU50 which is the prevalent variety in SEA. However, the use of transgenic material is subject to the authorization of each country to grow GM crops and this may take a long time before such technology could be deployed. However, such transgenic plants should be produced and multiplied in several locations if they were to be used at some point. The advantage of such method is that the transgenic KU50 would be absolutely identical to the original KU50 but with CMD resistance.
Strategic development of a CMD control plan
Controlling a virus disease in a vegetatively propagated crop, is declaring a war to viruses! Therefore, the same elements as for a war are needed to win the war:
1- Having resources to feed the plan; nothing will happen unless specific resources are identified and allocated to the plan. Search for international donors is required, contribution of local ministries is important, obtaining of international loans may be necessary.
2- Knowing the enemy (virus and whiteflies); more virus and whitefly identification in expert labs in the world are needed.
3- Knowing where and how much disease there is; more field evaluation to have a map of frequency of infection with CMD on time and space is primordial.
4- Building an armada to fight the enemy; full participation of country extension services is essential, involvement of international centers is required, involvement of expert labs is necessary, and coordination of all the actions is a must!
5- Having a strong communication system in place; communication with the international community to get their participation, communication between countries to get their active participation, communication between all actors for better coordination.
6- Having a lot of truly virus-free certified material; it is very important to have a protocol in place to multiply and verify that virus-free material is really virus-free. Sometimes we do not see symptoms but the stakes are infected.
7- Having a timely and effective distribution system, beginning with the most infected regions of the country; a best plan for the distribution should be discussed and put in place in each province.
8- Assessing the effectiveness of the plan; it is important to do a regular evaluation of the effect of the plan and if it does not work we better know it soon rather than continuing a non-effective plan. And if it is effective, we need to communicate the results to other parties in the team.
9- Set-up Regulations to prevent movement of cuttings across borders and between provinces; it is important to limit the spread from already infected provinces to virus-free provinces and it is important to forbid the importation of stakes between countries and outside the region to prevent spread and new importations. Regulations will need to be set-up and put in place.
Partnership for the plan:
An effective CMD control plan will require the participation of a number of players:
- National extension services will be required for the evaluation and collection of samples, and later for the multiplication and distribution of virus-free material. However, wherever possible private companies could participate to the plan, and virus-free certified cuttings could be sold.
- International centers have access to a number of tools that would be important for success; CIAT could play a major role in the regional coordination, IITA has experience with CMD viruses in Africa and should participate, CIAT has the best breeding team to introgress CMD2, IITA has geminivirus and whitefly experts, Japan has produced transgenic KU50 resistant to SLCMV, CTCRI in India has knowledge on controlling SLCMV and should be engaged in the team as well.
- Expert labs for virus and whitefly identification; there are a number of such labs in the US, Australia, Germany, China, France, UK and more than one lab could be involved.
- National and regional plan for propagation and spread; it is believed that the involvement of all 5 countries (at least 4!) is needed, even though some may not have any CMD yet on their territory, but it might just be a matter of time. Such alliance would be very strong to convince international donors. In addition, in each country a national project should be developed with specific actions. Clearly Thailand may not be involved in most of the plan, but Laos may soon be enrolled, while obviously Cambodia and Vietnam will be fully engaged!
Such a plan will require resources and if a good plan of communication is developed it will attract international donors; ACIAR, JICA, EU, AFD, IFC, IFAD, GIZ, UNDP, USAID… will be invited to the regional meeting and should be actively contacted for funding consideration of the plan. In addition, loans for the WB and AsDB and other agencies should be considered by the 4 countries to develop and fund an efficient plan of control, it is worth it on the long run.
Points of interest for further discussion
Transmission of the disease cuttings versus whiteflies
Level and speed of spread in the region
High level of virus detection for symptomless plants
Possibility to eradicate CMD from existing contaminated regions
How to implement an agreed regional plan
Possibility to associate the distribution/sale of new virus-clean varieties with eradication of infected varieties
Possibility to have regional policy for cuttings trades
Plan to get the buy-in of farmers and traders
Plan to involve the private sector wherever possible
Strategic organization for developing the CMD control plan
1- Country leaders will be appointed to constitute the list of key people to attend the regional meeting. It is very important to have in the room, scientists capable of elaborating the plan, administrators to make the link with ministries, association representatives to bet the buy-in of the farmers, the processors and the traders, and policy makers. However, we should keep in mind to have the smallest group possible as it will not be possible to manage a group above 50-60 people. Therefore, country leaders will be appointed to constitute the list of key people.
2- Topic leaders should be appointed for the elaboration of the plan; it seems that the elements of discussion listed above can be lump into 5 major topics:
a. Surveillance, diagnostic of virus and whiteflies, spatial distribution on time
b. Propagation of virus-free certified material in primary, secondary and tertiary sites
c. Development of a seed-system to distribute efficiently virus-free material, and link to the private sector
d. Varietal testing of new CVs and existing CVs resistant to CMD, and breeding CMD resistance into CVs for the region
e. Management of the plan, relationship with all partners including donors, budget issues and communication activities, board, progress meetings…
3- Organization of a round table with donors to identify possible funding and or discussing mechanisms to make the proposal and timeframe
4- Constitution of a writing team to complete the writing of the CMD control plan before leaving.
|Day 1 - Tuesday 18th September|
|7:00||Breakfast||Phnom Penh Hotel|
|8:00||Registration with Lee Pham||Phnom Penh Hotel|
|Welcome and Opening|
|8:30||Welcome||Dr Luis Augusto Becerra
Cassava Program Leader – CIAT
Dr Mak Soeun
General Director (Acting)
General Directorate of Agriculture
|8:45||Official Opening||Mr H.E. Veng Sakhon
Minister of Agriculture, Forestry and Fisheries
Departure of the officials
|Session 2 – Information sharing on current status and activities||Chair Luis Becerra|
|9:00||Setting the stage for the Regional meeting||Dr Claude Fauquet
GCP21 Adjunct Director
|9:15||Results of the CIAT-ACIAR study on the
spread of CMD and seed systems
in Vietnam and Cambodia
|Dr Nami Minato – CIAT-Hanoi
Mr Erik Delaquis – CIAT-Hanoi
|9:45||Report from Vietnam||Prof. Dr. Le Huy Ham
Chairman of Science Council
Institute of Agricultural Genetics
|10:15||Diagnostics in a coffee cup||Dr Jimmy Botella and Dr Mike Mason
University of Queensland
|11:00||Report from Cambodia||Mr. Op Pich
Deputy Director Department of Plant Protection,
Sanitary and Phytosanitary
|11:30||Potential economic impact of CMD in SEA||Dr Jonathan Newby
|12:00||Status of SLCMV in India||Dr Makesh Kumar
|12:30||Control of SLCMV in India||Dr Sheela
|14:00||CMD epidemiology in East Africa||Dr James Legg
|14:30||Breeding for CMD resistance in SEA||Dr Hernan Ceballos
|15:00||Breeding for CMD resistance in Africa||Dr Peter Kulakow
|15:30||New varieties from Thailand||Prof. Ed Sarobol
Faculty of Agriculture
|16:30||Survey and Surveillance of Cassava Mosaic Disease (CMD) in Thailand||Dr Phoowanarth MANEECHOAT
DOA - Thailand
|17:00||Lessons learn from Satreps in Vietnam||Trinh Xuan Hoat
PPRI - Vietnam
|19:00||Dinner||Phnom Penh Hotel|
|Day 2 - Wednesday 19th September|
|7:00||Breakfast||Phnom Penh Hotel|
|8:00||Registration with Lee Pham||Phnom Penh Hotel|
|8:30||Recap of Day 1 and outline Day 2||Dr Claude Fauquet|
|Session 3 – Discussion Round-Tables||Chair Steve Walsh|
|Round table working group introduction|
|Topic 1: Breeding and variety evaluations||Chairs: Ceballos-Kulakow|
|Topic 2: Diagnostics and Surveillance||Chairs: Cuellar - Legg|
|Topic 3: Virus free propagation, seed systems, agronomy||Chairs: Delaquis - Walsh|
|Topic 4: Policy, market engagement and communication||Chairs: Newby - Fauquet|
|11:00||Round Tables cont.|
|14:00||Turn around of the groups and chairs|
|16:00||Feedback working groups 10 min presentation + 5 min Q&A each|
|17:30||Close - Drinks|
|Day 3 - Thursday 20th September|
|8:00||Registration with Lee Pham||Phnom Penh Hotel|
|Session 4 - Identify donors for the CMD Control Plan||Chair Jonathan Newby|
|9:00||Round table discussion with donors and development partners|
|12:00||Closing remarks from Australian Embassy||Mrs Dulce Simmanivong
|12:45||Official Closing||Dr Claude Fauquet GCP21|
List of participants/strong>
br>- International experts in CMD epidemiology and control
- Members of the international community present in SEA
- Member officers of extension services from each country
- Representatives of DOAs from each country
- Key individuals for developing the project
- Potential Donor representatives