Selection of resistant spring barley accessions after natural infection with leaf stripe (Pyrenophora graminea) under organic farming conditions in Germany and by sandwich test

Six-hundreds-twelve barley (Hordeum vulgare L.) accessions were tested for resistance to Pyrenophora graminea under natural infection in an organic farm in Lower Saxony, Germany, during 1999-2002. More than 30% of these accessions were observed to be resistant in the field and are listed in this report. Varieties with previously documented 'Vada'- and 'Betzes'- resistance, were observed without infection, but those with 'Lion'-resistance and with 'Thibaut'-resistance were found to be susceptible. Many new sources of resistance from East Asia and also samples with deviating symptoms of sensitivity were found. A small group of accessions was infected artificially with two aggressive isolates of the pathogen (I2, I5) and tested by the sandwich method. This revealed both differences and agreement with the results obtained under natural infection. Accessions BGRC 5592, HOR 333, HOR 11475 and OU J362 showed resistance in all experiments.