Conifer seedlings damping-off in forest nurseries in the Krasnoyarsk region

The survey of forest nurseries indicated up 60 percent of conifer seeds and seedlings to die of contagious damping-off. The influence of hydrothermal conditions upon the progress of the disease has been determined. Pathogens have been specified in the samples from the zones with different soil and climate. The density of populations and contagious capacities of the pathogens have been described. The structure of populations was found to be formed under the canneling influence from conifer seedlings directed to the selection of clones on their virulent characteristics. The increase of contagious ability of species is closely allied to their population density.