Fig. 1

Powdery mildew life-cycle (Podosphaera plantaginis) and its hyperparasite Ampelomyces spp. on ribwort plantain (Plantago lanceolata). The powdery mildew life-cycle is shown in black and the Ampelomyces life-cycle in brown. The asexual part of the powdery mildew cycle is indicated by dashed (black) arrows while the sexual part is indicated by solid arrows. The powdery mildew life-cycle begins with the arrival of a spore on a susceptible host leaf. Then the mycelium grows and clonal spores (conidia) are produced. During the growing season, the pathogen is transmitted passively among hosts by wind dispersal of clonal spores. The pathogen survives winter as resting spores (chasmothecia) which contain sexually produced ascospores. Ascospores germination initiates a new epidemic in spring. The Ampelomyces life-cycle is strongly dependent on that of powdery mildew as it forms pycnidia within powdery mildew tissues. Hyperparasite spores are released from mature pycnidia and dispersed by rain-splash to nearby powdery mildew colonies