ARS | Publication request: Survey of Rhizoctonia spp. from wheat soils in the U.S. and determination of pathogenicity on wheat and barley

Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: March 1, 2011
Publication Date: June 1, 2011
Citation: Schroeder, K.L., Shetty, K.K., Paulitz, T.C. 2011. Survey of Rhizoctonia spp. from wheat soils in the U.S. and determination of pathogenicity on wheat and barley. Phytopathology. 101:S161..

Technical Abstract: Rhizoctonia root rot and bare patch are chronic diseases of wheat and barley in the Pacific Northwest (PNW), but little is known about Rhizoctonia spp. in other cereal growing areas of the U.S. A survey was conducted in the fall of 2009 and 2010 to identify Rhizoctonia spp. from soils collected throughout the wheat growing regions of the U.S. Soils were collected from 114 fields in 14 states and Rhizoctonia isolates were baited from these soils using a toothpick baiting method. Recovered isolates were identified by sequencing the ITS region of the rDNA and comparison of the sequence with the sequence of previously identified reference strains. Isolates were recovered from 49 locations and 51 isolates were sequenced. Rhizoctonia solani AG-2-1 (27%) and R. oryzae (Waitea circinata) (39%) were the most common species found. Rhizoctonia solani AG-3, AG-4, AG-10 and AG-11; and Ceratobasidium sp. AG-A and AG-I were also found. Interestingly, R. solani AG-8 was not found outside of the PNW. In pathogenicity assays conducted in the greenhouse in pasteurized soil, most isolates caused significant plant stunting and displayed typical root disease symptoms compared to the non-inoculated control. The highest disease ratings (0-8 scale) were observed with AG-3 (2.2 on wheat, 2.7 on barley), AG-A (1.9 on wheat, 2.8 on barley), and AG-4 (1.7 on wheat, 2.1 on barley). This data suggests that other groups of Rhizoctonia may be capable of causing damage on wheat and barley.