GROWTH OF LEEK RUST EPIDEMICS IN TIME IN 3 CULTIVARS DURING THE EARLY-STAGE OF THE EPIDEMIC

The growth of leek rust epidemics in time under favourable conditions in three leek cultivars during two years was analysed. In both years, the highest disease levels were found on cultivar Albana, followed by Carina and Cortina. A simple model is presented to correct the results for exchange of inoculum between adjacent plots. The results of this model indicate, that the difference in rust infection between the cult ivars may be due to a reduced growth of the epidemic in young plants o f cultivars Cortina and Carina. In older plants, the ranking in suscep tibility was reversed, causing a less pronounced difference in infecti on between the cultivars. The growth of leek rust epidemics during the early stage of the epidemic in isolated plots was satisfactorily desc ribed by an exponential model.