Roots of winter wheat grown in the field were examined for the occurrence of the fungi Gaeumannomyces graminis, Phialophora and Fusarium spp. Plants were sampled and examined in the autumn of 2000 and 2001 and in the following spring. Root systems were visually assessed and a percentage of affected roots were determined on 100 plants per field. More and less virulent members of the G. graminis- Phialophora complex and other fungi were isolated from infected roots. Above 85% of isolated fungi were classified as Gaeumannomyces-Phialophora complex. Morphological characteristics of the fungi isolated from plant roots were analysed in laboratory tests. In pathogenicity tests were assessed: disease severity, height of plants, percentage of chlorotic or necrotic leaves and biomass of whole plants.

In the Institute of Plant Protection Branch in Sośnicowice an investigation was performed on establishing novel methods for testing biological activity of seed dressings against snow mould (Microdochiwn nivale). Seeds of winter wheat used for the experiments in artificial conditions were disinfected in sodium hypochlorite, subsequently infected with the pathogen, and treated with seed dressing fungicides (Baytan Universal 19.5 WS, Zaprawa Funaben T, Maxim 025 FS, Raxil Extra 515 FS and Vitavax 200 FS). In laboratory tests inoculation with conidial suspension was applied, and in climatic chamber experiments either conidial suspension or inoculum grown on sand-cornmeal medium was used. The field experiment with the same seed dressings was carried out on naturally infested plots, and the disease developed under snow cover lasting for 58 days. Two novel climatic chamber methods (Z and PK) proved to be suitable for testing biological activity of seed dressing fungicides against snow mould (M nivale) as correlation coefficients with field results at P=0.05 were 0.9760 and 0.9453. Method Z was recognised as more suitable. Differences between seed dressings were statistically insignificant. The laboratory method was recognised as useful for controlling the pathogen (M. niva!e), but its usefulness for controlling the disease (snow mould) may not be sufficient under a range of different winter conditions.

In the years 2000 and 2001 the effectiveness of control of take-all (Gaeumannomyces graminis var. tritici) in winter wheat with seed dressing fungicides at different levels of root infection was studied. Seeds were treated with siltiofam, fluquinconazole or a standard fungicide Baytan Universal 094 FS. At low level of root infection recorded at GS 75 siltiofam and fluquinconazole significantly reduced root infection as compared to untreated control by 73.5-89.9% and 65.5-89%, respectively. At a medium level of infection the respective values were 56.2 and 54.9%. No significant differences between the efficacy of the two new fungicides were stated. Standard seed treatment product showed only limited activity in the early spring. Reduction of winter wheat root infection by 1% caused the increase of grain yield by around 1%.