A study was conducted to evaluate the agronomic performances of the sugar cane variety in relation to the nitrogenous manure and to the sensitivity of attack of the stems by the borers. The plant material is composed of the variety SP 70-1284. The test was conducted in the blocks of Fisher with 9 treatments to 4 repetitions. The total doses of N of three contributions for the cycle of harvest (35, 70, 105, 140, 175, 210, 245, 280, 0 kg ha-1 ) correspond to treatments T1, T2, T3, T4, T5, T6, T7, T8 and T0. The treatments T1 (0.92% ± 1.12), T0 (1.20% ± 1.54), T4 (1.58% ± 0.34) and T8 (2.14± 0.90) recorded the weakest rates of attack of the stems by the borers. The treatments T2 (2.37% ± 2.18), T7 (3.88% ± 1.82) T5 (3.92% ± 2.33), T6 (4.22% ±2.02) and T3 (4.80% ±2.01) noted the most elevated rates of attack. The weakest diameters of the stems are observed on the T0 treatments (2.14 cm ± 0.07), T2 (2.21 cm ± 0.19), T6 (2.22 cm ± 0.11), T3 (2.22 cm ± 0.15), T1 (2.23 cm ± 0.14) and T5 (2.29 cm ± 0.24). The T4 treatments (2.30 cm ± 0.20), T7 (2.32 cm ± 0.13) and T8 (2.42 cm ± 0.14) got the most elevated rates of attack of stems. A weak sensitivity of attacks of the stems to the Boers of the variety SP 70-1284 are observed with the N doses of 0 ha kg -1 , 35 kg ha-1 , 140 kg ha-1 , 280 kg ha-1 . These levels of nitrogen can be retained for the profitability of the variety SP 70-1280 in the culture of virgin cane at the complex Agro Industrial of CST-Banda in Chad
