Susceptibility of durum wheat to Fusarium graminearum, Blumeria graminis f.sp. tritici, and Zymoseptoria tritici in Poland.

Durum wheat is highly susceptible to fungal pathogens, which poses a significant challenge in its production. The aim of this study was to evaluate the health status of European spring cultivars of durum wheat grown in southern and northern Poland, to identify T. durum genes that confer resistance to Fusarium graminearum, Blumeria graminis, and Zymoseptoria tritici, and to select cultivars that are most resistant to changing environmental conditions in the temperate climate of Central Europe. Plant health was assessed in three-year field experiments, and the tested cultivars' sensitivity to inoculation with F. graminearum and accumulation of group B trichothecenes was analyzed in a greenhouse experiment. Resistance alleles were identified, and wheat plants' susceptibility to Fusarium head blight (FHB), Septoria tritici blotch (STB), and powdery mildew (PM) was determined in the PCR assay. In 2018-2019, symptoms of FHB were noted sporadically under field conditions, whereas in 2020, the disease was endemic in both experimental sites. In 2020, symptoms of Fusarium leaf blight (FLB) were observed in southern Poland, and symptoms of STB were noted in the northern part of the country. The severity of PM was low, and disease symptoms were observed mainly on lower leaves in all cultivars. Fhb2, Stb1, Stb2, Stb3, Pm36, and Pm41 alleles were identified in the tested cultivars. Cultivar IS Duragold grown in the greenhouse was least susceptible to primary infection by F. graminearum and the growth of fungal hyphae on the rachis. After inoculation, DON was accumulated in spikelets in all cultivars, in particular Duramant (1582 µg/kg) and Durasol (1455 µg/kg). Almost all of the tested cultivars were susceptible or very susceptible to FHB and STB, with the exception of IS Duragold and IS Duranegra which proved to be moderately susceptible. Susceptibility to FHB was inversely correlated with plant height and positively correlated with spike density. Tall cultivars with moderately dense spikes and a shorter flowering period were less susceptible to FHB.