Cassava witches' broom (CWB) is an important disease of Manihot esculenta Crantz that is widely cultivated across South East Asia. In 2010, more than 60,000 ha were affected in Vietnam with crop losses as high as 80%, and reductions in yield and starch content reached 30%. The disease was observed in Quang Ngai, Dong Nai and Yen Bai provinces of Vietnam, also affecting the availability of clean planting material. Studies were then carried out on the etiology of this disease to acquire information about its management. Aster yellows phytoplasmas were detected and restriction fragment length polymorphism analyses of nested PCRamplified fragments from Vietnamese CWB phytoplasmas indicated the presence of differentiable strains all related to the 16SrI group. Sequence analyses of partial 16S rDNA fragments showed that Vietnamese CWB phytoplasmas have 99% similarity with 'Candidatus Phytoplasma asteris'. To our knowledge, this is the first report of cassava infection with phytoplasmas related to the 16SrI group in Vietnam.
The data found suggest that the P. peruviana fruit juice anti-pterygium effect described in traditional medicine may be related to its inhibiting fibroblast growth. The present study contributes to the pharmacologic knowledge regarding a remedy commonly used in Colombian traditional medicine.
Cassava witches’ broom disease (CWBD) is one of the main diseases of cassava in Southeast Asia (SEA). Affected cassava plants show reduced internodal length and proliferation of leaves (phyllody) in the middle and top part of the plant, which results in reduced root yields of 50% or more. It is thought to be caused by phytoplasma; however, despite its widespread distribution in SEA still little is known about CWBD pathology. The overarching goal of this study was to review and corroborate published information on CWBD biology and epidemiology considering recent field observations. We report the following: (1) CWBD symptoms are conserved and persistent in SEA and are distinct from what has been reported as witches’ broom in Argentina and Brazil. (2) In comparison with cassava mosaic disease, another major disease of cassava in SEA, symptoms of CWBD develop later. (3) Phytoplasma detected in CWBD-affected plants belong to different ribosomal groups and there is no association study available indicating phytoplasma as the causing agent of CWBD. These findings are essential clues for designing surveillance and management strategies and for future studies to better understand the biology, tissue localization and spatial spread of CWBD in SEA and other potential risk areas.
Detection of Ralstonia solanacearum phylotype II, race 2 causing Moko disease and validation of genetic resistance observed in the hybrid plantain FHIA-21The International Center for Tropical Agriculture (CIAT) believes that open access contributes to its mission of reducing hunger and poverty, and improving human nutrition in the tropics through research aimed at increasing the eco-efficiency of agriculture.CIAT is committed to creating and sharing knowledge and information openly and globally. We do this through collaborative research as well as through the open sharing of our data, tools, and publications.
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