ABSTRACT
The microcystin concentration in the biomass of blue-green algae, in which Microcystis aeruginosa (up to 90%) dominates, was determined. The concentration of microcystin (cyclopeptide algotoxin) in suspension varies between 3.25 and 3.48 mg/dm3. As a result of preliminary laboratory studies, the inhibitory (fungicidal) effect of microcystin for Phytophthora infestans, which is a causative agent of tomatoes late blight, was proven. A pure Phytophthora culture was isolated, on which further studies were carried out. The plants biotesting was carried out after processing them with a suspension of blue-green algae, taking into account the toxic effects of microcystin on living organisms and their ability to bioaccumulate. The biopesticidal (fungicidal) effect of microcystins was established. The degradation of Phytophthora isolates was recorded the day after the colony was treated with a suspension of blue-green algae. A pronounced inhibitory effect of microcystin on the development of late blight was also revealed, almost until the symptoms completely disappeared in the tomatoes, which were partially affected by late blight and grew under natural conditions. As a result of biotesting, it was found that the plants treated with microcystin are safe for eating, since the mortality of the test objects is not fixed. The research results can serve as the basis for a deeper and broader study of the properties and possibilities of using microcystins as biopesticides in the agricultural production. In the experiment (five lines: control and application of 10, 25, 50 and 100 mg cells suspension/1 g of cultivation medium), the arithmetic mean of the chlamydospores number of Phytophtora nightshade sprouted in the Petri dishes on the oat-pea agarized medium was recorded.
