Root and Crown Rot Fungi Associated with Spring, Facultative, and Winter Wheat in Turkey.

The objective of this study was to determine the distribution frequency of the fungi associated with wheat (Triticum aestivum) crowns and roots in cereal producing areas of Turkey through a targeted survey of 518 commercial fields over a 2-year period. More than 26% of the fields had one or more of the fungal species commonly reported as part of the dryland root rot complex, Fusarium culmorum (14%) > Bipolaris sorokiniana (10%) > F. pseudograminearum (2%). The fungi considered to be part of the high rainfall root rot complex were found at very low frequencies: 2% for Gaeumannomyces graminis and 3% for Pythium spp. Species of Rhizoctonia were found in 22% of the fields. Several Fusarium species considered to be less or nonpathogenic to cereals were also found in high frequencies at 11% (F. oxysporum, F. chlamydosporum), 10% (F. sporotrichioides), and 8% (F. avenaceum and F. solani). The mostly random distribution of cereal root-rotting species across the survey area suggests the fungi are not distributed in any distinct agroecological relationship. As a result, the relative economic importance of a given species on wheat will be determined by a number of factors, such as their fungal pathogenicity, host susceptibility/tolerance, and the seasonal conditions. Results from this study suggest that there are a wide range of fungal species associated with root and crown tissues of wheat.