Genetic Structure of AG-2-2IIIB from Soybean in Illinois, Ohio, and Ontario.

AG-2-2IIIB is an important seedling pathogen of soybean in North America and other soybean-growing regions around the world. There is no information regarding the population genetics of field populations of associated with soybean seedling disease. More specifically, information regarding genetic diversity, the mode of reproduction, and the evolutionary factors that shape different populations separated in time and space are lacking.

Identification and Characterization of Rhizoctonia Species Associated with Soybean Seedling Disease.

In an effort to identify the Rhizoctonia spp. associated with seedling diseases of soybean, Rhizoctonia isolates were recovered from soybean seedlings with damping off and root and hypocotyl rot symptoms from Arkansas, Illinois, Kansas, Michigan, Minnesota, and the Canadian province of Ontario between 2012 and 2014. Based on cultural morphology, polymerase chain reaction restriction fragment length polymorphism, and phylogenetic analysis of the internal transcribed spacer (ITS) region of the ribosomal RNA genes, 80 isolates were confirmed to be Rhizoctonia solani, 24 were binucleate Rhizoctonia spp.

Sensitivity of Rhizoctonia solani to Succinate Dehydrogenase Inhibitor and Demethylation Inhibitor Fungicides.

Soybean seedling diseases are caused by Rhizoctonia solani and can be managed with seed-applied fungicides that belong to different chemistry classes. To provide a benchmark for assessing a decline in sensitivities to these fungicide classes, R. solani isolates collected prior to 2001 were evaluated for their sensitivities to succinate dehydrogenase inhibitor (SDHI) (penflufen and sedaxane) and demethylation inhibitor (DMI) fungicides (ipconazole and prothioconazole).