Susceptibility of cassava varieties to disease caused by Sri Lankan cassava mosaic virus and impacts on yield by use of asymptomatic and virus-free planting material

Cassava (Manihot esculenta Crantz) is a rainfed, smallholder-produced crop in mainland Southeast Asia, and is currently facing a serious challenge posed by the introduction of cassava mosaic disease (CMD). This study assessed the susceptibility of popular Asian varieties to CMD, yield penalties associated with the disease, and the efficacy of selecting clean or asymptomatic plants as seed for the following season. Field experiments evaluated agronomic management practices (ie, fertilizer application, use of symptomatic and asymptomatic seed stakes) in Cambodia with six to nine popular varieties over three seasons under natural disease pressure. Popular cassava varieties KU50 and Huaybong60 showed superior CMD tolerance, with consistently fewer symptomatic plants, lower disease progress measures, and higher yields. Plants demonstrating symptoms at early stages of development, ie, 60 days after planting, yielded significantly less than those developing symptoms later (ie, 270 DAP) or not at all. Plants grown from clean stems yielded on average 20% to 2.7-fold higher than those grown from symptomatic planting material. A yield decline of~ 50% was recorded with symptomatic planting materials of susceptible varieties (eg, SC8,~ 25 t ha− 1) over successive years. The findings emphasize that farmers could use positive selection by choosing asymptomatic plants to significantly reduce yield losses

Cassava rapid stem multiplication tunnel: Operations manual

This manual explains how to manage a cassava rapid stem multiplication tunnel system. A previous manual in this series described the construction of tunnels using common, locally available materials. In this manual, based on experiences from tunnel managers in Cambodia, Colombia, Lao PDR, and Vietnam, we describe the major stages and operations for rapid multiplication of cassava planting stems using the tunnel system

Cassava Witches’ Broom Disease in Southeast Asia: A review of its distribution and associated symptoms

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

Minimal anonimized SLCMV diagnostics data in Cambodia and Vietnam in 2016

The data includes diagnosis results of Sri Lankan cassava mosaic virus (SLCMV) from binational surveys of 15 districts in Vietnam and 16 districts in Cambodia, with 240 samples by district

Minimal anonimized SLCMV diagnostics data in Cambodia and Vietnam in 2016

The data includes diagnosis results of Sri Lankan cassava mosaic virus (SLCMV) from binational surveys of 15 districts in Vietnam and 16 districts in Cambodia, with 240 samples by district