Effect of some agronomic practices on the infestation with the sugar cane stem borer, Sesamia cretica Led. Lepidoptera: Noctuidae

The effects of some cultural practices i.e, planting dates, nitrogen fertilizer levels and planting spaces on the infestation with the sugar cane stem borer, Sesamia cretica Led. (Lepidoptera : Noctuidae). Corn plants sown in April plantation received the maximum numbers of the borer larvae with an average number of 23.5±5.5 and 28.7±5.8 larvae / 5 plants, while those sown in June plantation had the least numbers of the insect larvae with an average of 3.7±0.9 and 6.8±1.5 larvae / 5 plants. The plantation sown in July was intermediate with an average of 8.1±2.1 and 9.6±2.8 larvae / 5 plants during two successive seasons, the statistical analysis revealed that, highly significant differences in the numbers of S. cretica larvae in the three planting dates during both seasons. Increasing nitrogen fertilizer rates from zero to 360 Kg/ fed. Caused a significant increasing in rate of infestation with S. cretica. When supplying the corn plants with 360, 260, 160 and zero Kg nitrogen / fed., the rate of infestation with S. cretic were ( 26.5±6.4% - 24.6±7.1%), ( 15.0 ± 3.9%- 17.7±5.0%), (13.5±3.9% - 14.6±4.5%) and ( 7.7±1.9% - 10.1±3.3 %) to four nitrogen levels, respectively. The statistical analysis revealed that, in season 2006, there was highly significant difference in infestation with S. cretica among four rates of nitrogen fertilizer. On the other hand, there was significant difference between four rates of nitrogen fertilizer in 2007 season. Increasing planting spaces from 20 to 30 cm between hills caused insignificant decrease in the rates of infestation. The rates of infestation were (16.3±4.9% - 16.3±5.1%), (10.7±3.0% - 12.3±4.0%) and (9.0±2.4% - 9.7±2.9 %) to three planting spaces 20, 25 and 30 cm during two seasons 2006 and 2007 respectively. The statistical analysis revealed insignificant differences among the three planting spaces during both seasons.