Effect of pH, temperature and light on the pathogenicity of Cylindrocarpon destructans to pine seedlings in associative cultures with bacteria and actinomycetes.

Studies were carried out on the effect of pH, temperature, light and bacteria and actinomycetes on the pathogenieity of Cylindrocarpon destructans to pine seedlings. Two isolates, pathogenic to fir and pine were used. Depending on the cultural conditions both isolates were more or less pathogenic to pine. The isolate Dkm 229 exhibited much stronger pathogenic activity than the other one. The pathogenicity of the fungi depended upon the pH, temperature, light and accompanying microorganisms (bacteria and actinomycetes). Optimum pH for the pathogenicity of isolates Dkm 229 and Pkj 376 was 7,0 and 6,0 respectively. The aggressiveness of the strain Dkm 229 increased at lower temperature (15-18°C) and at lower light (700-800 lux). The isolate Pkj 376 exhibited a stronger pathogenicity at higher temperature (21-23°C) and higher light intensity (2100-2300 lux). Bacteria and actinomycetes introduced to the seedlings before fungal inoculation diminished the aggressiveness of the isolate Dkm 229, No such influence of both organisms on isolate Pkj 376 was noted. [ABSTRACT FROM AUTHOR]