Biological activity of 6 fungicides in the inhibition of Phytophthora ramorum sporulation and development of blight on rhododendron leaves and stems were evaluated. All tested compounds at dose 8 μg o fa.i./cm³ already inhibited zoosporangia formation at least in 73%. On leaf petioles and leaf disks, taken from rhododendron one week after treatment with fungicides, formation of chlamydospores was especially suppressed by fenamidone + phosetyl Al and oxadixyl + mancozeb whereas development o fspores was not inhibited by cymoxanil + famoxate. All tested compounds significantly inhibited the development and spread of twig blight on rhododendron. However, furalaxyl, applied as spraying of plants 48 hrs before or after inoculation of leaves and stems by P. ramorum was the most effective.

Phoma exigua var. inoxydabilis var. nov. predominated among fungal isolates obtained from diseased stem runners and leaves of periwinkle ( Vinca minor). The growth of the fungus was observed at temperature ranges from 7.5 to 30°C with optimum at 25°C. Abundant formation of picnidia was noticed mainly on malt extract agar at temp. I 5-25°C. On potato-dextrose agar picnidia were observed 3-5 days later. On inoculated leaves of periwinkle, development of necrosis was observed at temperature I0-25°C with optimum 20°C. On field grown periwinkle the first necrosis on the base of stem runners was observed 2 weeks after inoculation and during the next I O weeks discoloration of tissues occurred on about 1/2 of their length.