Sowing Time: A Crucial Factor for Mitigating Agrillus acutus (Buprestidae: Coleoptera) Infestation in Hibiscus cannabinus L. Cultivation

Kenaf (Hibiscus cannabinus L.) is one of the most important fibre crops next to cotton cultivated throughout the world for its core and bast fibres for industries with high economic value. Spiral borer, Agrilus acutus (Buprestidae: Coleoptera) is a serious pest of Kenaf. This experiment was undertaken with a view to find out the variation of infestation along with gall length of spiral borer in kenaf at different sowing dates. The experiment was conducted in two different locations namely Faridpur and Patuakhali jute research station at two kenaf growing seasons i.e. 2019 and 2018 following Randomized Complete Block Design with three replications. The highest infestation (49.78%) was found on 1st April 2018 in Patuakhali followed by 48.13%, 47.32% and 46.14%. The lowest infestation (13.33%) found on 20th May 2018 sown plot in Patuakhali followed by 13.65%, 13.97% and 14.91%. The highest gall length formation (46.21cm) was found in the plot that was sown on 1st April 2019, Faridpur followed by 45.65cm and 45.01cm. The lowest gall length (8.78cm) was recorded in 20th May 2019 sown plot in Faridpur. Correlation and regression study exhibited positive relationship between infestation (%) and gall length (cm). Here, it definitely showed that the gradual decrease in spiral borer infestation with the late sowing of kenaf. The lower the infestation, the lower the gall length of kenaf plant. Late sowing i.e. sowing after 13th to 20th May is the best option to avoid spiral borer infestation in kenaf cultivation.