scholarly journals A cassava mosaic disease epidemiologic factors analysis in the Bas-Congo (DR Congo) zone of savannah. case study: “Secteur de Boko”

2015 ◽  
Vol 3 (1) ◽  
pp. 56
Author(s):  
Bansimba Mukiese J.-Roger
Keyword(s):  
Disease Incidence ◽  
Mosaic Disease ◽  
Cassava Mosaic Disease ◽  
Dr Congo ◽  
Local Varieties ◽  
Epidemiologic Factors ◽  
Factors Analysis ◽  
Foliar Symptoms ◽  
The Mean

<p>This paper aims at evaluating epidemiologic parameters of the African Cassava Viral Mosaic Disease (CMVD) in 25 cassava farmer's fields of «Secteur de Boko» (DR Congo) on the basis of foliar symptoms observation. The results showed that the infection of the local varieties comes mainly from the cuttings whereas that of the improved varieties comes from the flies. The disease incidence varied between 10% and 88.33% with an average of 43.8%. Severity varied between 2.42 and 3.42 with an average of 2.913. The gravity varied between 17.86% and 87.81% while the systemicity varied between 21.42 and 96.66%. The mean number of whiteflies (<em>Bemisia tabaci</em>) by plant (2.068) revealed a preference of the vectors for the improved variety Kindombe which, however, presents a low severity and a less marked gravity. Globally, the CMVD was more severe for the local variety Mpeko with a score of 3.00. A high correlation was found between the gravity and the number of neighbour fields (-0,437*), the density of culture (-0,431*) and also the systemicity of the disease (0,779**). In addition; it appeared that the land topography strongly influences the disease severity (-0,542**).</p>

scholarly journals Evaluation and Characterization of High Yielding Cassava Mosaic Resistant Variety YTP2

2021 ◽  
pp. 198-208
Author(s):  
L. Pugalendhi ◽  
M. Velmurugan ◽  
P. S. Kavitha ◽  
M. K. Kalarani ◽  
N. Senthil ◽  
...  
Keyword(s):  
Tamil Nadu ◽  
Starch Content ◽  
Disease Incidence ◽  
Mosaic Disease ◽  
Dna Fingerprint ◽  
Cassava Mosaic Disease ◽  
Resistant Variety ◽  
Research Station ◽  
Internodal Length ◽  
New Variety

The cassava variety YTP2 (Me 681) has been developed through selection from Thondamuthur type at Tapioca and Castor Research Station, TNAU, Yethapur. The performance of YTP2 in the Adaptive Research Trial (ART) and On Farm Trial (OFT) in the farmer’s field inferred that this new variety is well adapted to cassava growing districts of Tamil Nadu. In addition to the above, YTP2 was found to be resistant to cassava mosaic disease incidence (CMD). Plants are erect, medium growing and non-branching type and suitable for growing under irrigated and rainfed conditions. The internodal length is shorter and the leaf size is medium with sufficient canopy. The leaves of the plants droop down to reduce the transpiration loss which is more advantageous to overcome or escape from drought and heat stress during summer season. It is a dual purpose variety wherein the tubers contain high starch content which is much favourable for the manufacture of starch, sago and also suited for table purpose. The overall performance of this variety showed higher tuber yield (42.20 t ha-1) and starch content (28.40%) which is 15.94% and 18.20% increase over the check varieties YTP1 and H226 respectively. The results of DNA fingerprint data involving SSR markers (SSRY235, NS169 and NS928) showed that it is genetically distinct from the existing commercial varieties viz., YTP1, H226 and Sree Athulya.

scholarly journals Evaluation of whitefly population and weather effect of cassava mosaic incidence on commonly grown cassava in Benue State, Nigeria

2020 ◽  
Vol 24 (10) ◽  
pp. 1839-1846
Author(s):  
I Time ◽  
E Okoroafor ◽  
J.O. Nwogwugwu ◽  
A.A. Batcho
Keyword(s):  
Wind Speed ◽  
Wind Direction ◽  
Disease Incidence ◽  
Natural Infection ◽  
Block Design ◽  
Mosaic Disease ◽  
Cassava Mosaic Disease ◽  
Whitefly Population ◽  
North East ◽  
Vector Population

Vector population and weather are critical in virus disease incidence and could be strategic for its management in agriculture. To investigate the influence of whitefly population and weather on Cassava Mosaic Disease (CMD) in cassava, TMS 419 and TME 30572, commonly grown in the state were planted. The varieties were laid out in Randomized Complete Block Design in four replicates and left to natural infection by CMD viruses. At two weeks after planting and fortnightly, whitefly population counts were taken, CMD incidence was estimated and severity scored on 5- point scale. Daily temperature, humidity, wind speed and wind direction were obtained as secondary data. Data were analysed using ANOVA at p=0.05. Whitefly population (18/plant) was significant (P≤0.05) in the first 30 days at 26.9-27.1oC, 42% humidity, 10 Km/hr wind speed and when the wind direction was in the East or North-East. The vector population then declined until the end of experiment. Cassava mosaic incidence changed with whitefly population, humidity and wind speed. Disease incidence in cassava plots was low (3.6%). TME30572 maintained lower disease incidence (3.0%) and severity (2.0) during the study. R2 indicated that 27, 42 and 57% of whitefly population could be explained by temperature, humidity and wind speed, respectively while 4% of the disease incidence could be explained by the whitefly population. The number of CMD infected plants peaked (4%) when population of whitefly was 18/plant, above which the disease reduced at 0.0017 rate per unit change in the vector population. Mosaic disease incidence in cassava plots was influenced by vector population as conditioned by the weather. Keywords: Bemisia tabaci, Cassava, Cassava Mosaic Disease, Nigeria, Weather, Whitefly vector

Effect of African cassava mosaic disease on morphological characteristics of cassava, Manihot esculenta (Crantz)

2015 ◽  
Vol 11 (2) ◽  
pp. 258-265
Author(s):  
TF Oyadiran ◽  
JA Osakwe
Keyword(s):  
Disease Incidence ◽  
Morphological Characteristics ◽  
Field Trials ◽  
Mosaic Disease ◽  
Cassava Mosaic Disease ◽  
Petiole Length ◽  
Manihot Esculenta Crantz ◽  
Key Word ◽  
Mechanized Agriculture ◽  
Number Of Branches

Field trials were conducted with 10 improved clones of cassava to study the effect of ACMD on their morphological characteristics. The clones used were: 97 / 4763, 97/2205, 91/02324, 98/0505, M98/0068, 96/1089A, 96/1632, M98/0040, 99/2123 and 97/0162. The parameters measured were plant height, leaf area, number of branches and petiole length. The research revealed differences within the clones for the parameters studied, these differences seemed to be mainly genetic, as they were not positively correlated to the disease incidence and severity. Based on the findings in this research the following recommendations were made. On the basis of their branching pattern, highly branched clones 97 / 2205, 97/4763 and 98 /0505 are recommended for selection. The heavy branches bear a lot of leaves or produce a thick canopy which helps to reduce the need for weeding, and also reduce the effect of loss of leaves that occur due to disease incidence. However, for industrial / mechanized agriculture, clones that are less branched should be selected as they are easier to harvest mechanically. Though there is disadvantage with their small leaf areas; the crops would have to be highly resistant to fungal attack which tends to cause leaf drop that will reduce leaf material for food / starch production (examples of less branching clones are, M98 / 0068, 96/1632,91/02324).Key Word: African Cassava Mosaic Disease (ACMD), Cassava Mosaic Virus.(CMV)

scholarly journals Effect of Fertilizer Level and Planting Distance on Soil pH, Growth, Fruit Size, Disease Incidence, Yield, and Profit of Two Papaya Varieties

1969 ◽  
Vol 61 (1) ◽  
pp. 68-76
Author(s):  
A. Pérez ◽  
D. Vargas
Keyword(s):  
Soil Ph ◽  
Management Practices ◽  
Disease Incidence ◽  
Fruit Size ◽  
Mosaic Disease ◽  
Net Profit ◽  
The Mean ◽  
High Yielding Varieties ◽  
Planting Distance ◽  
Poor Management

Papaya production in Puerto Rico is low, probably because of diseases and poor management practices. In this study, high yielding varieties were used to compare planting distances and fertilising practices. Plants of varieties PR 6-65 and PR 7-65, planted at 1.8 x 1.8 m were significantly larger than those at 1.2 x 1.2m. The larger size of the plants was reflected in an increase in fruit yield and net profit. PR 6-65 produced a significantly heavier crop and a higher net profit/ha than PR 7-65. PR 6-65 was significantly more susceptible to the Isabela mosaic disease and more tolerant to bunchy top than PR 7-65. Soil pH was significantly lower at the 1.2 x 1.2m planting distance than at the 1.8 x 1.8 m, probably because more fertilizer was used in the closer planting. There were no significant differences between the mean yields of papaya plants receiving monthly applications of .227 and .454 kg of a 15-15-15 fertilizer, suggesting that the smaller amount of fertilizer is enough to produce a heavy crop and obtain a good net profit from papayas grown in Coto clay, an Oxisol.

scholarly journals Incidence, Severity and Gravity of Cassava Mosaic Disease in Savannah Agro-Ecological Region of DR-Congo: Analysis of Agro-Environmental Factors

2012 ◽  
Vol 03 (04) ◽  
pp. 512-519 ◽  
Author(s):  
Marcel Muengula-Manyi ◽  
Kabwe K. Nkongolo ◽  
Claude Bragard ◽  
Patrick Tshilenge-Djim ◽  
Stephan Winter ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Mosaic Disease ◽  
Cassava Mosaic Disease ◽  
Dr Congo ◽  
Ecological Region

scholarly journals Evaluation of Newly Released Cassava Varieties for Yield Performance, Reactions to Cassava Diseases and Farmers’ Preference in Adjumani District of Uganda

2021 ◽  
Vol 13 (4) ◽  
pp. 84
Author(s):  
Alex Abaca ◽  
Emmanuel Odama ◽  
Alfred Komakech ◽  
Baron Asiku ◽  
Andema A. Andrews ◽  
...  
Keyword(s):  
Mosaic Disease ◽  
Cassava Mosaic Disease ◽  
Yield Performance ◽  
Foliar Symptoms ◽  
Information Gap ◽  
Root Necrosis ◽  
Cassava Brown Streak Disease ◽  
New Varieties ◽  
Rot Disease ◽  
Cassava Varieties

Cassava viral diseases particularly cassava brown streak disease (CBSD) and cassava mosaic disease (CMD) have put pressure on cassava breeders to develop varieties that are resistant/tolerant to them. Several cassava varieties have been rolled out to farmers with the latest being NAROCASS series that are tolerant to these diseases. The yield performance of these new varieties have not been documented in some sub zones like Adjumani district that falls within a major West Nile agro-ecology of Uganda. Therefore this study sought to established yield performances of, reactions to major diseases, and farmers&rsquo; preference to these newly released cassava varieties in Adjumani. Results showed significant (P &le; 0.05) differences among cassava varieties and experimental sites for all the parameters evaluated. Average yield performance by varieties were in the order of a local cassava&mdash;Alifasia (8.7 t/Ha) lowest, NAROCASS 2 (18.55 t/Ha), NASE 14 (33.97 t/Ha), NASE 19 (41.26 t/Ha), and NAROCASS 1 (41.71 t/Ha) highest. CMD foliar symptom was present at all sites on a local cassava&mdash;Alifasia, and on NAROCASS 1 in Ayiri parish, Ukusijoni sub-county. CBSD foliar symptoms were observed on off-types (TME 14) in the plot of NASE 14 in Miniki Parish only whereas CBSD root necrosis was observed at all sites on the local cassava&mdash;Alifasia, and on NASE 19 in Maaji parish, Ukusijoni sub-county. Cassava root rot disease was localised in Ukusijoni sub-county only. Farmers&rsquo; preferences to these newly released cassava varieties were in the order of NASE 19 (40.96%), NAROCASS 1 (24.86%), NAROCASS 2 (15.82.28%), NASE 14 (15.54%), and a Local cassava&mdash;Alifasia (2.83%). Result from this study strengthens the information gap in the breeding process towards developing a cassava variety with farmer-preferred attributes, and can also inform the utilisation of these improved cassava varieties in Adjumani district.

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

2013 ◽  
Vol 04 (04) ◽  
pp. 824-837 ◽  
Author(s):  
Marcel Muengula-Manyi ◽  
Lyna Mukwa ◽  
Kabwe K. Nkongolo ◽  
Patrick Tshilenge-Djim ◽  
Stephan Winter ◽  
...  
Keyword(s):  
Mosaic Disease ◽  
Cassava Mosaic Disease ◽  
Dr Congo ◽  
Genetically Improved ◽  
Cassava Varieties

scholarly journals Survey and molecular detection of Sri Lankan cassava mosaic virus in Thailand

PLoS ONE ◽  
2021 ◽  
Vol 16 (10) ◽  
pp. e0252846
Author(s):  
Kingkan Saokham ◽  
Nuannapa Hemniam ◽  
Sukanya Roekwan ◽  
Sirikan Hunsawattanakul ◽  
Jutathip Thawinampan ◽  
...  
Keyword(s):  
Mosaic Virus ◽  
Disease Severity ◽  
Disease Incidence ◽  
Rolling Circle Amplification ◽  
Mosaic Disease ◽  
Cassava Mosaic Disease ◽  
Pcr Analysis ◽  
Nucleotide Sequencing ◽  
Sri Lankan ◽  
Cassava Mosaic Virus

Cassava plantations in an area of 458 hectares spanning five provinces along the Thailand–Cambodia border were surveyed from October 2018 to July 2019 to determine the prevalence of cassava mosaic disease (CMD) caused by Sri Lankan cassava mosaic virus (SLCMV) in the region. CMD prevalence was 40% in the whole area and 80% in Prachinburi, 43% in Sakaeo, 37% in Burium, 25% in Surin, and 19% in Sisaket provinces. Disease incidence of CMD was highest 43.08% in Sakaeo, followed by 26.78% in Prachinburi, 7% in Burium, 2.58% in Surin, and 1.25% in Sisaket provinces. Disease severity of CMD symptoms was mild chlorosis to moderate mosaic (2–3). The greatest disease severity was recorded in Prachinburi and Sakaeo provinces. Asymptomatic plants were identified in Surin (12%), Prachinburi (5%), Sakaeo (0.2%), and Buriram (0.1%) by PCR analysis. Cassava cultivars CMR-89 and Huai Bong 80 were susceptible to CMD. In 95% of cases, the infection was transmitted by whiteflies (Bemisia tabaci), which were abundant in Sakaeo, Buriram, and Prachinburi but were sparse in Surin; their densities were highest in May and June 2019. Nucleotide sequencing of the mitochondrial cytochrome oxidase 1 (mtCO1) gene of whiteflies in Thailand revealed that it was similar to the mtCO1 gene of Asia II 1 whitefly. Furthermore, the AV1 gene of SLCMV—which encodes the capsid protein—showed 90% nucleotide identity with SLCMV. Phylogenetic analysis of completed nucleotide sequences of DNA-A and DNA-B components of the SLCMV genome determined by rolling circle amplification (RCA) indicated that they were similar to the nucleotide sequence of SLCMV isolates from Thailand, Vietnam, and Cambodia. These results provide important insights into the distribution, impact, and spread of CMD and SLCMV in Thailand.

scholarly journals Effects of Vector Maturation Time on the Dynamics of Cassava Mosaic Disease

2021 ◽  
Vol 83 (8) ◽  
Author(s):  
F. Al Basir ◽  
Y. N. Kyrychko ◽  
K. B. Blyuss ◽  
S. Ray
Keyword(s):  
Time Delay ◽  
Plant Density ◽  
Plant Viruses ◽  
Mosaic Disease ◽  
Plant Diseases ◽  
Cassava Mosaic Disease ◽  
Maturation Time ◽  
Negative Effect ◽  
Dynamical Regimes

AbstractMany plant diseases are caused by plant viruses that are often transmitted to plants by vectors. For instance, the cassava mosaic disease, which is spread by whiteflies, has a significant negative effect on plant growth and development. Since only mature whiteflies can contribute to the spread of the cassava mosaic virus, and the maturation time is non-negligible compared to whitefly lifetime, it is important to consider the effects this maturation time can have on the dynamics. In this paper, we propose a mathematical model for dynamics of cassava mosaic disease that includes immature and mature vectors and explicitly includes a time delay representing vector maturation time. A special feature of our plant epidemic model is that vector recruitment is negatively related to the delayed ratio between vector density and plant density. We identify conditions of biological feasibility and stability of different steady states in terms of system parameters and the time delay. Numerical stability analyses and simulations are performed to explore the role of various parameters, and to illustrate the behaviour of the model in different dynamical regimes. We show that the maturation delay may stabilise epidemiological dynamics that would otherwise be cyclic.

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