Relating germination dynamics of Melampsora pinitorqua teliospores to temperature and rainfall during overwintering.

The influence of overwintering conditions on the dynamics of Melampsora pinitorqua teliospore germination in spring was assessed in the Landes forest, south-western France, over 3 years. January accumulated temperature was the variable most strongly linked to the date of optimum germinability (JDOG), in a negative direction. A linear regression using accumulated degree-days and number of rainy days in January accounted for nearly 70% of overall variation in JDOG. Accumulated temperature from October 1 and January 1 to the date of optimum germinability showed lower coefficients of variation than JDOG.