2.3.4
STRATEGIES OF PATHOGEN LIFE CYCLES

EU TOROPOVA and VA CHULKINA

Novosibirsk Agricultural University, Krasnoobsk 633128, Novosibirsk region, a/y 18, Russia

Background and objectives
The well-developed ecological concept of r- and K-strategies of biological species has a continued useful application in the field of plant epidemiology [1].

Results and conclusions,
Analysis of the life cycles of 250 widely spread and harmful plant pathogens allowed us to establish four ecological strategies: r-, k-, rK-, Kr. The strategies differ from each other in universal qualitative and quantitative features of reproduction, survival and trophic relationships of pathogens. Knowledge of these strategies allowed us to determine the potential types of seasonal and perennial dynamics of the pathogen, systems for monitoring and a strategy for plant disease control. For example, r-species, (rusts, true mildew on wheat) have unstable dynamics and require frequent monitoring during a short period of time; the strategy of control is therefore directed at restriction of epidemic spread during the growing season. K-species (common root rot, potatoe common scab) have a moderately invariable type of dynamics and require monitoring once or twice a season; the strategy of control is directed at decreasing the number of the original pathogen population before the growing season.

References
1. Chulkina VA, Toropova EU, 1997. Environmental orientation. Plant Protection and Quarantine 1, 13-14.