STUDY OF DIFFERENT SOWING DATES OF MAIZE CROP ON MAIZE APHIDS, RHOPALOSIPHUM MAIDIS INFESTATION

Studies on the effect of different sowing dates of maize against the infestation of maize aphid (Rhopalosiphum maidis) were carried out at Agricultural Research Institute (ARI) Tarnab, Peshawar, Pakistan with RCB design having 7 treatments, replicated four times during 2003. The results revealed that aphid infestation was high in plots sown on 3rd week of June. Then it was declined in the plots sown from the 4th week of June till the 2nd week of July. After that, the infestation increased again with a maximum of 4.03 % in the plots sown during the last week of July. Cobs weight data (per m²) showed that maximum yield was recorded in plots sown on 20th June and 8th July with cobs weight of 0.297 and 0.259 Kg, respectively, while the minimum yield was recorded in plots sown in the last week of June and July where the yield was 0.159 and 0.168 Kg, respectively. These values were significantly different from each other as well as from the other plots. Thousand grain weight observations indicated that maximum weight was found in plots sown on 20th and 26th June with grain weights of 280.0, 263.8 gm respectively and minimum yield was observed in plots sown in the 3rd and 4th weeks of July where it was 166.3 and 135.0 gm, respectively. It is concluded from this experiment that in order to avoid maize aphid infestation, the crop may be sown in last week of June or 2nd week of July.