Incidence of major pests of okra in relation to weather factors and cropping systems

Abstract

Incidence of major pests (shoot and fruit borer, Earias vittella; leafhopper, Amrasca biguttula biguttula; whitefly, Bemisia tabaci and red spider mite, Tetranychus urticae) of okra (cv. AO-1) was studied in two cropping systems (organic and conventional) in relation to weather parameters at Navsari Agricultural University, Navsari Gujarat, India during 2017-18. The investigation indicated peak shoot and fruit borer population (3.88 and 3.27 larvae/plant) and its associated fruit damage (39.56 and 35.60 %) during 20th week after germination (WAG) (11 SMW) indicating significant positive association with temperature (minimum and average), relative humidity (evening and average), bright sunshine in both the farming systems whereas, positive association with wind velocity in conventional farming system was also reported. Peak leafhopper population (11.66 and 12.70/ leaf) was noticed at 6 WAG (15 SMW) exhibiting significant positive correlation with maximum temperature. Adult whitefly population remained highest (3.07 and 3.61/ leaf) during 11 WAG (20 SMW) exhibiting significantly positive correlation with average temperature and bright sunshine in both the farming systems. Red spider mite population peaked (23.69 and 27.52 /2 cm2 leaf area) during 13 WAG (22 SMW) and 11 WAG (20 SMW) at organic and conventional farms, respectively which in turn indicated significant positive association with minimum and average temperature, evening and average relative humidity and wind velocity.