Seasonal incidence of stem fly insect on soybean plants

The experiment was conducted to determine the seasonal incidence of stem fly, Ophiomyia phaseoli Tryon in the soybean field of Breeder Seed Production Center, Bangladesh Agricultural Research Institute, Debiganj, Panchagarh. Seeds were sown on six different dates from early August to mid September, 2014 maintained intervals of 7 days at August 09 to September 13. There was no significant (P > 0.05) effect observed among the sowing times on the abundance of stem fly population. The number of larva and pupa per plant were recorded from 1.17 to 1.33 and 0.85 to 1.02, respectively. However, the percentage of infested plant and stem tunneling differed significantly among the sowing dates. The highest infested plant (83.71%) and stem tunneling (40.87%) were obtained from the crop sown on mid September. But the lowest infested plant (70.64%) and stem tunneling (25.31%) were obtained from the crop sown on 23 August. The maximum (2.20 t/ha) and minimum yield (1.60 t/ha) were obtained from crop planted at the 3rd week of August and 2nd week of September, respectively.