Impact of climatic factors and vector population on incidence of Phyllody in Sesame under rainfed cultivation

Abstract

Phyllody is a severe disease caused by a phytoplasma and transmitted by leaf hopper, Orosius albicinctus Distant is a major controlling factor in accomplishing full yield potential of the sesame crop. Sesame crop was grown during kharif season of the year 2018 and 2019 with three sowing dates to investigate the influence of vector population and climate variability on occurrence of phyllody and the pooled data was analyzed. Studies on correlation of leaf hopper population and climatic factors indicated that, the leaf hopper population evinced significant positive correlation with maximum temperature (r=0.775), minimum temperature (r=0.525) and mean temperature (r=0.7), while, non-significant negative correlation with minimum relative humidity (r=-0.3), mean relative humidity(r =-0.41) and significant negative correlation with maximum relative humidity (r=-0.524) and rainfall (r =-0.55). Among the three sowing dates, the highest population was observed in the crop sown during first fortnight of June followed by crop sown during the second fortnight of June and first fortnight of May. Correlation between the climatic factors and phyllody incidence has indicated that the phyllody exhibited significant positive correlation with maximum temperature (r=0.709), minimum temperature (r=0.535) and mean temperature (r=0.705) while, non-significant negative correlation with maximum relative humidity (r=-0.445), minimum relative humidity (r=-0.242), mean relative humidity(r=-0.338) and significant negative correlation with rainfall (r=-0.565). Phyllody incidence was highest in the crop sown in the second fortnight of May, incidence was significantly decreased with delayed sowing in both the years. It was also revealed that the vector population had significant positive correlation with the phyllody incidence (r=0.979). Variation in yield realization was also observed owing to dates of sowing. Higher yields were recorded in the crop sown during first fortnight of June (372.2 kg/ha) and second fortnight of May (365.5 kg/ha) compared the to crop sown during second fortnight of June (298.6 kg/ha).