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International audience; Cassava is the most important vegetatively propagated food staple crop in Africa. Even if its vegetative propagation through stem cuttings has many advantages, it also represents its Achilles heel. Pathogens are passed from one generation to the next and can easily accumulate, threatening cassava production. Two viral diseases are currently considered to be the greatest global threat to cassava production in Africa. Faced with the gravity of this situation, 43 scientists from African national and regional institutions and international agricultural research centres met in Saint-Pierre, La Réunion Island from 10 to 13 June 2014, to contribute to the surveillance and control of cassava diseases and pests that threaten the food security and livelihoods of millions Africans. The main action was to consolidate and develop a global alliance against cassava diseases in Africa and a strategic action plan with several international initiatives for the coming years. Firstly, the establishment of a Pan-African Cassava Surveillance Network (PACSUN) with an interactive website and an International Cassava Transit Site (ICTS) in La Réunion. Secondly, the development of diagnostic technologies to better identifying viruses, bacteria and vectors, and a comprehensive educational and training plan to support all these activities. (Texte intégral)

Cassava is the most important vegetatively propagated food staple crop in Africa. Even if its vegetative propagation through stem cuttings has many advantages, it also represents its Achilles heel. Pathogens are passed from one generation to the next and can easily accumulate, threatening cassava production. Two viral diseases are currently considered to be the greatest global threat to cassava production in Africa. Faced with the gravity of this situation, 43 scientists from African national and regional institutions and international agricultural research centres met in Saint-Pierre, La Réunion Island from 10 to 13 June 2014, to contribute to the surveillance and control of cassava diseases and pests that threaten the food security and livelihoods of millions Africans. The main action was to consolidate and develop a global alliance against cassava diseases in Africa and a strategic action plan with several international initiatives for the coming years. Firstly, the establishment of a Pan-African Cassava Surveillance Network (PACSUN) with an interactive website and an International Cassava Transit Site (ICTS) in La Réunion. Secondly, the development of diagnostic technologies to better identifying viruses, bacteria and vectors, and a comprehensive educational and training plan to support all these activities. (Texte intégral)

Following the open comment period for MusaNet and ProMusa members in September 2015, the ''BSV Position Paper'' was finalized and is now available here. The purpose of the position paper was to propose a strategy for the distribution of germplasm containing infective endogenous BSV in the B genome, while minimising any risk associated with the distribution of BSV to the recipient country. Comments on the paper were well received and addressed by the taskforce. Please click here for a summary of the comments and responses. The next step is for the International Transit Centre (ITC) to develop an official procedure for the distribution of eBSV infected germplasm based on the position paper. This will be discussed in the MusaNet Expert Committee and reviewed by the taskforce (pictured below) that developed the position paper. The strategy will be implemented after all of the ITC accessions containing the B genome are screened and cleaned if necessary. This is currently being carried out by CIRAD and the University of Liege, Gembloux Agro-Biotech, and is expected to be completed by the end of 2016. If you have any questions or comments, please contact Rachel Chase at r.chase@cgiar.org.

Soybean production in Tanzania is steadily increasing, driven by growing demand from feed and livestock producers and also for human consumption. Soybean production area has increased from 795 ha in 2003 to 4,100 ha in 2013 (FAO 2014). Major soybean production is in the Morogro, Ruvuma, Iringa, and Mbeya regions. During a soybean rust disease survey conducted in May 2014 in Morogoro in the southern highlands of Tanzania, soybean plants with phyllody and witches’-broom disorder typical of phytoplasma infection was observed on cultivar, Uyole Soya#1 in a farmer’s field at Msufini village (6°17′0.099″ S; 37°28.791″ E). Symptoms consisted of shoot proliferation, reduced size of the leaflets and petiole, proliferation of axillary shoots with shortened internodes, phyllody, and viriscence. About 50% of the plants assessed (n = 20) from one plot in a farmer’s field were infected. Symptomatic and asymptomatic leaves were collected for total genomic DNA extraction and PCR amplification using Candidatus phytoplasma universal primer pair P1 and P7 for 16S-23S ribosomal RNA encoding region (Sharmila et al. 2004). PCR amplicons of expected size (∼1,700 bp) resulted from the templates of the symptomatic samples only. They were directly sequenced in both orientations and the nucleotide sequence was submitted to GenBank (Accession No. KP205526). A BLASTn search revealed that the phytoplasma sequences had a nucleotide sequence identity of 99% with those of 16SrII group phytoplasma associated with phyllody and witches’-broom disease of soybean in Malawi (HQ845208) and Mozambique (HQ840717). Phylogenetic analysis revealed the clustering of these strains with members of 16SrII group. The virtual restriction fragment length polymorphism (RFLP) pattern derived from these sequences using iPhyClassifier software (Zhao et al. 2009) was similar to the reference pattern of the 16SrII subgroup C (cactus phytoplasma, AJ293216), with a pattern similarity coefficient of 0.99. Previous reports of phytoplasma occurrence in Tanzania were related to coconut lethal decline disease caused by 16SrIV-C subgroup phytoplasma (Bila et al. 2014). To our knowledge, this is the first report of the occurrence of 16SrII-C subgroup phytoplasma causing phyllody and witches’-broom disease in soybean in Tanzania. The occurrence of phyllody and witches’-broom disease was first recognized in soybean in Malawi and Mozambique in 2010 (Kumar et al. 2011). Detection of the same pathogen in the diseased soybean plants in Tanzania suggest either spread of 16SrII phytoplasma from neighboring countries or 16SrII phytoplasma may be widespread in asymptomatic wild or weed hosts in southern Africa, spreading to crop hosts like soybean because of intensive cultivation. Nonetheless, this finding underscores the need for better understanding of epidemiology of 16SrII phytoplasma, especially its natural hosts and vectors, to prevent its adverse impacts on soybean production in Eastern and Southern Africa. Further surveys in soybean production areas in Tanzania are necessary to estimate the extent of spread and economic importance

International audience; no abstract

The overall goal of the five year project “Yam Improvement for Income and Food Security in West Africa” (YIIFSWA) funded by the Bill and Melinda Gates Foundation and led by the International Institute of Tropical Agriculture, Ibadan, Nigeria was to: (a) increase yam productivity by 40% for 2,00,000 smallholder yam farmers in Ghana and Nigeria and (b) deliver key global good research products that will contribute to the 10-year overall vision to sustainably double incomes from yams for 3 million smallholder yam farming families and contribute to ensuring food security for producers and consumers. Implemented by scientists of twenty partner specialized organizations, comprising research institutes, Universities, governmental and non-governmental organizations, YIIFSWA has impacted yam value chain stakeholders through research and development interventions. The significant contributions made in the project during the past 18 months’ period are discussed in this paper. These include: a baseline survey conducted in key yam growing areas in Ghana and Nigeria, training of yam producers on adapted yam minisett technique and production of seed yam, undertaking in depth value chain assessments, developing the capacity of Farmers Organizations (FOs) by linking them to service providers (SPs), participatory evaluation of new yam genotypes, successful development of yam virus diseases diagnostics and development of novel techniques for high ratio yam propagation such as aeroponics and bioreactors.