Cultural and morphological characteristics of fungus Phoma sp.1 – Phoma blight causing agents in coniferous tree seedlings

Abstract

Phoma blight of coniferous seedling − a new and poorly understood disease in forest nurseries of the country. The main causing agentsis a pathogenic species Phoma sp.1, for the moment, has no tax-onomy description. The basic morphological and cultural characteristics of the fungal strain Phoma sp.1 are investigated in this paper. It was found that the according to the optimum temperature (22° С) the fungus belongs to the mesophilic group. It was found that the culture of Phoma sp.1 have been capable of forming a vegeta-tive resting spores − chlamydospores.The process of formation began with the separation of protoplasm fragments, then the mycelium septated and covered with a dense shell. Chlamydospores formation was the most rapid agar medium at +4°C for 7 days cultivation. Pycnidia of the fungus formed deep in the nutrient media only after prolonged low-temperature storage of mycelium on agar media, but the spores have not been ripen. The influence of pH on the relative fungus it is acidophilic. Maximizing biomass productivity rate was into the 4.3–4.9 range, but the growth of the fungus Phoma sp.1 is can be carried out in a wide pH range – from 2.5 to 8.5 depending on the composition of the nutrient medium. In the process of life fungus alters the reaction medium at a different number of pH units, bringing it closer to optimal for it development. The pH of the medium also affected cellular and colony morphology of Phoma sp.1. More favorable conditions for the fungus Phoma sp.1 observed at constant medium aeration – the formation of the typical mycelium with pr oportional growth and stable biomass accumulation.