Impact Assessment Of Different Sowing Dates On Maize Aphid, Rhopalosiphum Madis Infestation In Bangladesh

Maize (Zea mays L.) is attacked by many insect-pests which are the principal limiting factor for its productivity all over in Bangladesh. The maize aphid, Rhopalosiphum maidis is one of the most destructive pests of maize as second important cereal crop after rice. The present investigation was set up at the Entomology Field Laboratory, Department of Entomology, Bangladesh Agricultural University (BAU), Mymensigh during Rabi season of 2016-17 in order to assess the impact of different sowing date on maize aphid infestation under field condition and it’s also effect on morphological, phenology, yield attributes and yield of maize. The experiment was laid out in randomized complete block design (RCBD) having three replications. Maize var. BARI Hybrid Butta-09 variety was used as experimental crop. Nine sowing dates viz. 3rd(S1) & 4th(S2) week of October, 1st(S3), 2nd(S4), 3rd(S5) & 4th(S6) week of November and 1st(S7), 2nd(S8) & 3rd(S9) week December were used as treatments. To assess the impact of different sowing dates, different data were collected from randomly selected five plants from each replicated plots at different growth stage i. e. vegetative, inflorescence and cob formation stage at least three times based on three main parameters such as entomological features (healthy & infested plants, inflorescences & cobs; body length(mm), number of aphid per plant and inflorescence), morpho-physiological characters (Plant height, cm) and yield attributes & yield (number of cob plant-1, cob length without husk (cm), diameter of cob without husk (cm), number of grain cob-1, grain weight cob-1(g) and grain yield, t ha-1). The results revealed that 1st week of November (S3) as sowing date was found the best for suppressing the maize aphid, and morpho-physiological characters, yield attributes and grain yield was also the best compared to others sowing dates due to ensuring the lowest percentage of infested maize plant at vegetative stage (36.91%), inflorescence stage (43.12%), cob formation stage (20.53%) & average the lowest percentage of infested maize (33.52%), and the highest plant height (223.66cm), number of cob plant-1 (1.73), cob length without husk (23.23cm), diameter of cob without husk (16.17cm), number of grain cob-1 (641.21), grain weight cob-1(235.16) and maximum grain yield (10.56 t ha-1). Furthermore, based on average aphid infestation, the increasing order of infestation due to different sowing date were S4