EN
The effect of Maize dwarf mosaic virus (MDMV) infection and Sugarcane mosaic virus (SCMV) infection on maize plants was studied in two-year field experiment with three maize varieties. The experiment was carried out in field conditions with the protection of the plants from aphid infestation with the special net. The plants were mechanically inoculated with the viruses. The effects of MDMV and SCMV on 3 maize cultivars were evaluated using disease symptoms (plant height), total yield, yield of kernels and the weight of 1 000 kernels. The results were statistically analyzed. The most important effect of the viruses was the reduction of the yield of kernels, ranging from: 46.0 to 69.8% for MDMV-P2 and from 48.8 to 69.8%, for SCMV-P1.