Screening durum wheat cultivars for resistance traits against the stem-base pathogen Fusarium graminearum

Durum wheat is not a traditional crop in countries with a temperate climate, but the growing demand for semolina in the food processing industry has increased the popularity of this cereal species in the farming sector. The pathogens responsible for Fusarium crown rot (FCR), eyespot, and sharp eyespot contribute to lodging, disrupt the translocation of water and nutrients in plants, and decrease yields. The present study was conducted in several dozen locations in Poland to determine the severity of FCR, eyespot, and sharp eyespot in more than ten durum wheat cultivars, to identify stem-base pathogens, to analyze the virulence of Fusarium graminearum, and to evaluate the effectiveness of seed dressing in reducing the severity of infections in durum wheat seedlings. Durum wheat cultivars were screened in field and plot experiments in Poland. The virulence of F. graminearum and the effectiveness of biological and chemical seed dressing in reducing the incidence of FCR were determined in vivo. In the studied locations, symptoms of FCR and eyespot were observed on 16-76% and 1-36% of durum wheat stems, respectively, on average. Sharp eyespot was noted only in one year of the study in a single location (1-6%). The severity of the analyzed diseases was generally low. Fusarium avenaceum, F. culmorum, F. graminearum, F. oxysporum, F. poae, F. solani, and F. sporotrichioides were isolated from stems with symptoms of FCR. The number of F. graminearum and F. culmorum isolates was significantly positively correlated with the severity of FCR symptoms (r = 0.480 and r = 0.485, respectively). Fusarium graminearum was identified in 15 locations, and F. culmorum was detected in six locations. Seed treatment with triticonazole reduced the number of ungerminated kernels by 42.6% in comparison with the untreated control. Seed treatment involving Debaryomyces hansenii decreased the number of ungerminated kernels by 31.1% on average, but this effect was noted only in cv. Floradur. All durum wheat cultivars evaluated in Koch's postulate test were severely infected, but F. graminearum isolates differed in virulence. Fusarium graminearum was the most prevalent pathogen in durum wheat stands, and it was highly virulent for seedlings. To decrease the incidence of FCR in durum wheat stands, new resistant varieties should be tested, suitable farming locations with desirable soil and environmental conditions should be identified, and new agricultural treatments should be developed.