Maize genotypes reactions against ear and kernels rots causal organisms studied under natural infection at two plant density and different harvest dates at Sakha Agricultural Research Station. Field experiments were designed in split plot design in four replications during summer Season of 1999 and 2000. The main finding could be summarized as follows: The results showed that single crosses 107 and 122 gave the lowest degree of infection by ear and kernel rot disease under the low plant density (20,000 plants/fed). The single cross 120 and Bashaier-13 gave intermediate reaction, while the open pollinated varieties Giza-2 and Bush gave the highest degree of infection by all tested disease at both low and high plant densities. Moreover, Fusarium moniliforme was predominated on/in the maize grains. Its frequency percentage tended to high in all tested cultivars grown at all harvest dates, and its infected the kernels before any other agents of kernel or ear rot. On the other hand, Penicillium Sp., Aspergillus flavus and Aspergillus miger caused high infection in only late harvest date (135 days after planting). Generally, increasing plant density from 20,000 to 30,000 plants/fed. has significantly increasing for the ear and kernels rot disease, while the ear length, ear diameter, number of kernels/row and number of rows/ear were decreased. The optimum plant density was 20,000 plants/fed, which gave the low degree of infection and high production of grain yield production.