Rhizoctonia solani on coniferous seedlings in forest nurseries

Rhizoctonia solani was isolated from 1/4–2 year-old seedlings of Silver fir, European larch, Scots pine and only sporadically from Norway spruce with symptoms of stem and root rot and yellowing and browning of needles. The species occurred on at least half of analysed, diseased plants. In laboratory trials the species colonised all parts of seedlings of Silver fir, European larch, Scots pine, Norway spruce and also Common alder and birch. On inoculated leaves of alder and birch necrosis spread about twice quicker than on needles of coniferous plants. Isolates from Norway spruce and Scots pine colonised plant parts quicker than from Silver fir and European larch. In greenhouse trial all isolates caused necrosis of 4 coniferous species and alder seedlings.