MSc

In the pest management programme identification of insect free stages in crop growth is vital for avoiding excessive pesticide use in pest management practices. In order to identify the sowing periods of bhindi which will keep the pest population low, a field experiment was laid out in the instructional low, a field experiment was laid out in the Instructional Farm of the College of Agriculture, Vellayani, extending over a period of fifteen months. Ten high yielding varieties obtained from different sources were sown at monthly intervals. Observations on incidence of jassid S. biguttula biguttula, shoot and fruit borer E. vittella and the leaf roller S. derogate were taken and the data were subjected to statistical analysis.
The following conclusions were obtained from the studies.
1. In all varieties the population of jassids was found to be at higher level from 47th to 61st days after sowing. Control operations may be required only during these periods.
2. Jassid populations on different varieties sown in each month were so widely varying that any variety showing similar resistance/susceptibility in all the sowings could not be identified.
3. Jassid infestation was high in November to January sowings and low population was noted in February, june, July, August and September sowings.
4. Jassid population showed significant negative correlations with rainy days, rainfall and relative humidity and a positive association with the maximum temperature.
5. In general March and April sowings had the highest incidence of shoot borer in all sowings in all varieties.
6. Significantly higher incidence of fruit borer was seen in April sowing.
7. In majority of the varieties crop sown in April and September suffered behavior damage due to the incidence of leaf roller.
8. In general February, May, June, July, August, September and October sowings of bhindi had very low incidence of jassid and shoot and fruit borers.
9. Bhindi sown in January, May, October and December gave significantly higher yield in majority of the varieties included in the present investigations.