EFFECTS ON GROWTH OF WHEAT PLANTS OF ISOLATES OF GAEUMANNOMYCES PHIALOPHORA-COMPLEX FUNGI IN DIFFERENT CONDITIONS OF SOIL-MOISTURE, TEMPERATURE, AND PHOTOPERIOD/

The effects on spring wheat (Triticum aestivum L., cv. Mario) of nine isolates of the Gaeumannomyces/Phialophora complex, ranging from non-p athogenic to pathogenic, were studied under different conditions of so il moisture, soil temperature, and photoperiod in growth chambers whic h simulated different autumn weather conditions. The experimental cond itions were based on data (e.g. temperature) from representative sites (loamy sand, Muencheberg, Northeast Germany) collected in the last th ree decades. The results of seedling inoculation tests for four nonpat hogenic isolates were partly in agreement with results from field tria ls done over 4 years. One non-pathogenic G. graminis var. tritici isol ate (G 33) increased consistently dry weight of shoots in the simulati on, and grain yield in field experiments. For non-pathogenic isolates, warm temperatures with moderate soil moisture most often stimulated p lant growth, with less effect in cold dry soil conditions. The decreas e in seedling growth caused by pathogenic isolates was influenced only slightly by temperature changes, but was often enhanced by increased soil moisture.