Results of biological investigations on wide-spread pathogenic fungi Cercospora acetosellae, C. armoraciae, C. beticola, C. carotae, C. meliloti, C. microsora, C. radiata, C. rautensis and C. zonata are presented. The fastest germination of conidia and colony growth of the most harmful Cercospora fungi in Lithuania occur at a temperature of 22–27 oC. Short-term irradiation by UV-rays stimulates the development of conidia and inhibits the growth of mycelium at the same time. Wide-spread plant pathogens C. microsora and C. meliloti in vitro showed the best growth on natural media (pH-5–8). C. microsora is harmful under variable climatic conditions: wet and warm or hot summer as well as cool summer, since this plant pathogen is active even at 17 oC. At this temperature (pH 6.5) pectines and albumens are most intensively decomposed. Amylases are the most active under the temperature of 22 oC and cellulasis have high endogliuconasic activity even at 30 oC (pH 6.5). Improperly-balanced fertilization might stimulate conidia formation and spreading of Cercospora caused leaf spot. Among investigated fungicides in vitro the most effective against C. microsora were 2 % Bordeaux solution and 0.2 % sportak, among fungicides used against C. meliloti – 1.5 % TMTD and 1 % burgundy solution. Some antibiotics (tetraciklin together with nistatin, and nistatin) affect the plant pathogens causing Cercospora leaf spot.
Keywords: fungi, Cercospora, biological properties, plant pathogens, Lithuania.