Breeding cassava for resistance to cassava mosaic disease

Hahn, S. K.; Terry, Elein; Leuschner, K.

doi:10.1007/bf00023215

Cited by 194 publications

(187 citation statements)

References 10 publications

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“…The CMD incidence represented the percentage of diseased plants compared to the total number of plants present in the plot. The CMD symptom severity was assessed for each plant in the plot using a scale of 1 to 5 described by Hahn et al, [12] and Terry and Hahn [13], where: 1 = no symptoms; 2 = mild chlorosis, mild distortions at bases of most leaves, while the remaining parts of the leaves and leaflets appear green and healthy; 3 = pronounced mosaic pattern on most leaves, narrowing and distortion of the lower one-third of the leaflets; 4 = severe mosaic distortion of two thirds of most leaves and general reduction of leaf size and stunting of shoots; and 5 = very severe mo-saic symptoms on all leaves, distortion, twisting, misshapen and severe leaf reductions of most leaves accompanied by severe stunting of plants.…”

Section: Data Recorded and Statistical Analysismentioning

confidence: 99%

Assessing Reactions of Genetically Improved and Local Cassava Varieties to Cassava Mosaic Disease (CMD) Infection in a Savannah Region of the DR-Congo

Muengula-Manyi¹,

Mukwa²,

Nkongolo³

et al. 2013

AJPS

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The responses of eight genetically improved and eight local cassava varieties to cassava mosaic disease (CMD) were evaluated under field conditions at two sites, in Eastern Kasaï, region of the DR-Congo). The varieties were planted using randomized complete block design with three replications. The rate of cuttings sprouted varied significantly from variety to variety and from location to location. Local varieties were severely infected than improved varieties throughout the trial period. In general, the level of CMD incidence for genetically improved varieties was below 15% while it reached 100% for the local cassava varieties six months after planting (MAP). This trend was also observed for the CMD severity and gravity. The mean scores for CMD severity were 2 and 3.6 for genetically improved and local varieties, respectively at 6 MAP. CMD gravity for improved varieties was below 21% for genetically improved varieties and exceeded 85% for local varieties at the end of trials. Area Under the Severity index Progress Curve (AUSiPC) and Area Under Disease Progress Curve (AUDPC) estimates confirmed that improved varieties were moderately infested comparatively to local varieties. Molecular analysis is being conducted to determine the genetic variability and complexity of the cassava mosaic virus strains involved.

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Section: Data Recorded and Statistical Analysismentioning

confidence: 99%

Assessing Reactions of Genetically Improved and Local Cassava Varieties to Cassava Mosaic Disease (CMD) Infection in a Savannah Region of the DR-Congo

Muengula-Manyi¹,

Mukwa²,

Nkongolo³

et al. 2013

AJPS

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“…This indicates that the leaves reflected little diffused light within red-green region compared with the reflections from the blue-yellow region. The pink regions in the b* layer describe the diffuse reflections from the yellow portions of the original image, confirming the fact that yellow reflects more light to the human eye than any other colour in the visible region (Hahn, Terry, & Leuschner, 1980).…”

Section: Resultsmentioning

confidence: 53%

Optical Imaging Method for Determining Symptoms Severity of Cassava Mosaic Disease

Anderson¹,

Eghan²,

Asare‐Bediako³

et al. 2015

APR

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Cassava mosaic disease (CMD) is a major constraint to cassava production in cassava growing regions. Severity of CMD symptoms on cassava leaves is usually assessed visually using an arbitrary scale, which is semi-qualitative, and does not represent the actual surface area of diseased leaf. The objective of this study was to develop a quantitative method of assessing the severity of CMD. A combination of polarimeteric digital colour images, L*a*b* colour model and K-means clustering algorithm were used to determine the areas of CMD symptoms and healthy areas on leaves. The severity of CMD on a leaf is determined by computing the percentage of the CMD symptomatic area to the total leaf area. The analysis provides relatively fast and accurate classification of Cassava mosaic diseased leaves. The proposed method will enable plant scientists to obtain accurate and reliable data, forming the basis for better decision making.

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“…Percentage of infested plants = Number of plants with CGM damage / Total Number observed × 100 Severity for both pests and diseases was scored on a scale of 1 to 5 where 1 represents no symptom and 5 represents severe infection/infestation (Hahn et al, 1980;Muimba, 1982;Muyolo 1984;Legg and Bouwmeester, 2010) at 3, 6 and 9 months after planting.…”

Section: Scoring Pests and Diseasesmentioning

confidence: 99%

Effect of modified spacing arrangements, fertilizer use and legume intercrop on prevalence of cassava brown streak disease in Western Kenya

Ememwa¹,

Wéré²,

Ogemah³

et al. 2017

Afr. J. Agric. Res.

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Cassava is an important food security crop in Western and Coastal counties of Kenya. As a food security crop, it is continuously cultivated with minimal inputs. Its production is constrained by factors like declining soil fertility, poor agronomic practices, pests and diseases. Cassava brown streak disease (CBSD) is a viral infection attacking the cassava crop causing yield losses of up to 100%. The current study was intended to determine the effect of planting technologies on the prevalence of CBSD in two agro-ecological zones of Western Kenya: lower midland (LM1) and upper midland (UM1). Various spacing arrangements, four fertilizer regimes, legume intercrop and improved cassava cultivars were tested in a randomised complete block design (RCBD) with each site as a replicate. Data was collected on pathogen population and disease incidences and severity, and cassava and legumes yields. Results showed no effect of modified spacing and legume intercrop on CBSD incidence. However, incidences varied by cassava cultivar (9 to 59%) and fertilizer application (3 to 41%). Low CBSD incidences (3 to 16%) were observed over time in management strategies involving fertilizer NPK 17:17:17 suggesting that vigour enhancement may have contributed to low CBSD incidences. Low incidence of CBSD on improved cultivars indicates that CBSD can be mitigated through crop improvement technologies such as breeding for resistance to diseases. Intercropping cassava with beans and modification of spacing did not demonstrate an effect on CBSD incidence. However, 2 m× 0.5 m spacing arrangement can compensate for rising land pressure in Western Kenya and areas facing similar problem.

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Breeding cassava for resistance to cassava mosaic disease

Cited by 194 publications

References 10 publications

Assessing Reactions of Genetically Improved and Local Cassava Varieties to Cassava Mosaic Disease (CMD) Infection in a Savannah Region of the DR-Congo

Assessing Reactions of Genetically Improved and Local Cassava Varieties to Cassava Mosaic Disease (CMD) Infection in a Savannah Region of the DR-Congo

Optical Imaging Method for Determining Symptoms Severity of Cassava Mosaic Disease

Effect of modified spacing arrangements, fertilizer use and legume intercrop on prevalence of cassava brown streak disease in Western Kenya

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