Resistance to common bunt is a highly desirable trait in wheat cultivars suitable for organic growing. Over 1000 germplasms were analysed for common bunt resistance during 2006–2008. In 2007, none of the 474 genotypes tested was found to be highly resistant, while 8 accessions were resistant. Investigations in 2008 showed two accessions to be highly resistant and 28 resistant out of the 714 modern germplasms tested. Among the tested genotypes with the known resistance Bt1–15,Z genes, only two single resistance genes conferred complete effectiveness in cultivars ‘PI 554120’ and ‘Yayla 305’ possessing Bt8 and in ‘Eryth-5221’ possessing Bt14. The other single resistance genes considered as effective (infection up to 10.0%) were Bt5, 9, 11, 12, 13, 15, Z. Among the most resistant modern cultivars, none was free from infection during both years. Cultivars characterized as at least moderately resistant during both years were ‘Sana’, ‘Penta’ and ‘Sj05–15’ with the 0.0–8.5% infection level. The most susceptible cultivars ‘Azimut’ and ‘Champion’ were infected up to 99.0% on average, and in some replications infection was as high as 100.0%. Infection range from 0 to 100% proved that the infection of cultivars was adequate for the characterization of the test genotypes by resistance to common bunt. More than 800 breeding lines were tested during the two screening years. Only five lines were infected no more than 10% during both years.

Keywords: wheat, common bunt, resistance genes, organic growing