Seed-borne fungi affect field emergence in red clover

In three field experimental sites, effects on clover establishment and yield of seed fungicidal treatments and seed heat treatment, using hot air in a newly developed process, were measured. Disease severity indices were, in addition, assessed for plant roots grown from treated seeds in the greenhouse for 4 months. Significantly more plants, on average 38 %, were established from heat-treated seed while fungicidal treatment gave an average increase of 4 %. Yields were not significantly different between treatment, but showed a similar trend as plant count data. Isolation of fungal pathogens from untreated non-surface sterilized seed and from 2-week-old diseased seedling roots showed the seed to be infested with different Fusarium spp., Penicillium spp., Alternaria spp. and Phoma sp., while isolations from diseased roots and hypocotyl were dominated by Phoma medicaginis var. pinodella. Root disease severity indices were in greenhouse tests reduced by 40-45 % and by 17-23 % in plants grown from heat-treated seeds and from fungicide-treated seeds, respectively.