Ecology, Environment and Conservation Paper

IMPACT OF CLIMATIC FACTORS AND VECTOR POPULATION ONINCIDENCE OF PHYLLODY IN SESAME UNDER RAINFEDCULTIVATION

Saritha R., Sujatha V., Sirisha Abm and Haseena S.K.

Abstract

Phyllody is a severe disease caused by a phytoplasma and transmitted by leaf hopper, OrosiusalbicinctusDistant is a major controlling factor in accomplishing full yield potential of the sesame crop. Sesame cropwas grown during kharif season of the year 2018 and 2019 with three sowing dates to investigate the influenceof 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 populationevinced 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 relativehumidity (r=-0.3), mean relative humidity(r =-0.41) and significant negative correlation with maximumrelative humidity (r=-0.524) and rainfall (r =-0.55). Among the three sowing dates, the highest populationwas observed in the crop sown during first fortnight of June followed by crop sown during the secondfortnight of June and first fortnight of May. Correlation between the climatic factors and phyllody incidencehas 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 negativecorrelation with maximum relative humidity (r=-0.445), minimum relative humidity (r=-0.242), mean relativehumidity(r=-0.338) and significant negative correlation with rainfall (r=-0.565). Phyllody incidence washighest in the crop sown in the second fortnight of May, incidence was significantly decreased with delayedsowing in both the years. It was also revealed that the vector population had significant positive correlationwith the phyllody incidence (r=0.979). Variation in yield realization was also observed owing to dates ofsowing. Higher yields were recorded in the crop sown during first fortnight of June (372.2 kg/ha) andsecond fortnight of May (365.5 kg/ha) compared the to crop sown during second fortnight of June (298.6kg/ha).