Prevalence of Okra Yellow Vein Mosaic Viral Disease and its Correlation with Vector Population in Sindh, Pakistan

Abstract

Okra (Abelmoschus esculentus (L.) Moench) being an important vegetable crop is widely grown in tropical and subtropical regions of the world. Whitefly (Bemisia tabaci) is not only a major insect pest of okra in Pakistan but also the vector insect of Begomoviruses including okra yellow vein mosaic virus which causes okra yellow vein mosaic viral disease (OYVMVD). Regional monitoring of insect vectors and disease prevalence is being emphasized for proper management, therefore this study was focused on determining the intensity of OYVMVD in the fields and the correlation between the disease and vector population. For this purpose, the virus infection was confirmed with DNA sequencing. The disease and vector population was visually assessed approximately 65-70 days after sowing of okra under field conditions at commercial farmer fields in district viz., Hyderabad, Tando Allahyar, Matiari, and Sanghar of Sindh, Pakistan during the growing season of 2016. Ten okra plants with three replications (N = 30) at ten different locations of each district were assessed. Results of nucleotide alignment of DNA amplified from diseased plants confirmed that yellowing and vein clearing were due to the virus infection. The visual assessment showed that the disease was prevailing throughout all region monitored in this study and the disease was significantly correlated with the vectors population. However, maximum disease incidence and severity were recorded in Tando Allahyar. Therefore, it is recommended to validate various management practices at such high disease risk points for better management