The effect of three planting dates (August 25, September and October) on infectivity of root- knot nematode species and productivity of sugar beet var. Pleno was evaluated. The results indicated that the 1st planting date showed the highest values of nematode infection parameters (i.e. numbers of galls, eggmasses, development stages root system-1, juveniles in soil and final population as well as reproduction factor) followed by 2nd planting date. However, the 3rd planting date achieved the lowest values of those nematode parameters. In addition, the data revealed that the 1st planting date obtained only the highest values for sucrose and purity percentages. On the other hand, the 3rd planting date recorded the highest values of roots, top, biological and sugar yields (tons fed-1). Therefore, the 3rd planting date (during October) was the most effective date against concerned species of root-knot nematodes on naturally infested sugar beet grown in sandy soil using drip irrigation system.