In recreational areas, such as parks and golf courses, plants like white clover are considered as weeds. In an attempt to identify biocontrol agents that can be used to control growth of clover, a number of bacterial isolates were studied. Two approaches were considered: soil treatment
for suppression of Rhizobium leguminosarum, a symbiotic bacteria providing clover with nitrogen, and direct suppression by leaf-spray treatment. Selected bacterial isolates were first screened against R. leguminosarum in a dual culture. Some of the tested isolates significantly inhibited the
growth of R. leguminosarum. Soil inoculation of these isolates had a significant growth-reducing effect on clover seedlings. Leaf-spray treatment of bacteria had a significant impact on clover growth. Depending on the plant growth stage, this effect can reach up to 86% reduction in clover
shoot dry weight. Different temperatures did not influence the effect on clover. The growth-reducing effect of bacteria was also shown on another important dicotyledonous weed, Chenopodium album.