In 1997-1999 observations of health status of spring barley grown in two-component mixtures with cereals or pea were performed in two experiments, differing in the agricultural utility of soil. A much better health status of the studied species was found in the mixed crop than in their pure stand. Two-component mixtures were differentiated in the occurrence of leaf diseases caused by Drechslera teres, Drechslera graminea, Puccinia graminis and P. hordei, Rhynchosporium secalis and Erysiphe graminis. The healthiness of lower parts of stem and roots depended on the quality of soil and mixtures factor. A higher infection due to foot root rot complex was noted on barley cultivated on the poorer soil in homogenous stand.

Terrain and laboratory research were conducted to determine the potential of Gastroidea viridula Deg. (Coleoptera: Chrysomelidae) to control mossy sorrel (Rumex confertus Willd.). In a field study, the dynamicof plant biomass and number of larvae occurring on that plant were investigated. The Pearson’s linear correlation coefficient of biomass increase in time equalled, to r = 0.96. The regression equation showed, that the plant daily growth reached 29 g; and 210 g per week, consequently. In the laboratory, weight of consumed food by larvae, and larval body weight were measured at 20°C. First generation of G. viridula was taken into consideration. Total weight of consumed leaves by all three instars of a single larva, during 50 days of the development amounted to 1.243 g. Also seasonal abundance of larvae was observed. On May 25th the highest observed number of G. viridula larvae per plant ranged from 435 to 469 individuals. This species may be of usefulness in biological control of mossy sorrel.