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Cassava; Cassava mosaic virus disease; Cassava mosaic streak virus disease; Assessment

Introduction

Based on the invitation made by Tarpeza Development Association (TDA) on 12/1/2023, survey was carried out at cassava field and diseased leaf samples were collected for identification of diseases that attacks cassava plant [1]. Totally four farmers’ fields were surveyed at 3 km interval alongside the main roads and diseased leaf samples were collected for further reference [2]. Diseases identification was made based on visual inspection/observation made on symptoms produced on the external parts of the leaf, stem and by dissecting tuberous root part of the cassava [3]. Incidence of cassava mosaic disease was calculated as the percentage of plants with symptoms. Severity was assessed using the 1 to 5 severity scale of the International Institute of Tropical of Agriculture (IITA) (1990), where 1 = no visible symptoms, 2 = mild chlorotic patterns, 3 = mosaic patterns on all leaves and leaf distortion, 4 = mosaic pattern on all leaves, leaf distortion, and a general reduction in leaf size and 5 = misshapen and twisted leaves and stunting of the whole plant (Figure 1) [4,5].

Figure 1: Scale used in scoring for cassava mosaic disease.

Table 1: Description of survey sites and Cassava Mosaic Diseases pressure

Conclusion and Recommendation

Cassava mosaic virus disease (CMD) and Cassava mosaic streak virus disease (CMSD) are the most severe and widespread, limiting production of the crop in sub-Saharan Africa. During field scouting cassava leaf showed symptoms like leaf chlorosis (discoloration), distortion and reduction in leaf size and stunting of the whole plant but no symptoms were observed by external parts of the stem and root even in the internal part of the root (by dissecting tuberous root of the cassava). Based on visual inspection/observation and by comparing literature descriptions made on cassava diseases symptoms produced, the diseases was identified as Cassava mosaic disease. This is because Cassava mosaic disease symptoms were mostly observed on leaf parts of the cassava but that of the Cassava mosaic streak virus diseases symptoms were observed in leaf, stem and internal part of the root (tuberous root necrosis). So the disease observed during survey was identified as Cassava mosaic viral disease. Future research is needed for the assessment of more agro-ecologies and molecular identification of the pathogen in addition to morphological identification.

Acknowledgements

The Authors acknowledge Areka Agricultural Research Center and Tarpeza Development Association (TDA) for their material support.

Competing Interests

The authors declare that they have no competing interests.

References

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