In forest nurseries, F. circinatum causes pre- and post-emergence damping-off of seedlings [11] and mortality of established seedlings [3]. Main symptoms are collar rot and wilting [2], but under certain conditions, seedlings can be asymptomatic and may develop the disease after they are transplanted to plantations [2,11]. From an epidemiological point of view, host growth stage is an important parameter influencing disease intensity that should be taken into account for disease management [16]. Viljoen et al. [3] found that mortality of established seedlings tends to be lower than that of newly germinated seedlings, and Storer et al. [11] determined that seedling emergence from infested Monterey pine seed was 9% compared with 67% for non-infested seeds. Another important epidemiological parameter is the infection rate [16], for which there are no available data, comparing infection of newly germinated seedlings and established seedlings.