Submitted to: Plant Health Progress
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/26/2011
Publication Date: N/A
Citation: N/A Interpretive Summary: Charcoal rot is a disease of soybean caused by the fungus (mold) Macrophomina phaseolina that causes significant economic yield losses in the United States and around the world. Efforts to manage charcoal rot in soybean through cultural practices, fungicide applications and biological control had limited effects on disease severity. Host resistance may be the only feasible method to manage this disease. Reactions of 27 maturity group III, 29 early maturity group IV, 34 late maturity group IV, and 59 maturity group V soybean genotypes were evaluated in 2006 through 2008 in a field that had been artificially infested for three years, had been in no-till production, and was not irrigated. Based on root colonization, there was no genotype that was immune in all three years but, there were a total of seven genotypes with one genotype in MG III, one in Late MG IV and five in MG V that were identified as moderately resistant. Some of the commercial and public cultivars were resistant to charcoal rot equal to or greater than the standard DT97-4290, a moderately resistant cultivar. The genotypes identified as having moderate resistance for three years could be useful as a source for resistance in developing high yielding resistant soybean cultivars.
Technical Abstract: Charcoal rot caused by Macrophomina phaseolina causes more yield loss in soybean than most other diseases in the southern U.S.A. There are no commercial genotypes marketed as resistant to charcoal rot of soybean. Reactions of 27 maturity group (MG) III, 29 Early MG IV, 34 Late MG IV, and 59 MG V genotypes were evaluated for M. phaseolina between 2006 and 2008 in a field that had been infested for three years, been in no-till production, artificially infested, and was not irrigated. There was great variation in root colonization among genotypes and years, indicating the value of screening genotypes over multiple years. Based on consistent CFUI performance of each year there was no genotype that was immune. However, there were a total of seven genotypes with one genotype in MG III, one in Late MG IV and five in MG V that were identified as moderately resistant. Some of the commercial and public genotypes were resistant to M. phaseolina at levels equal to or greater than the standard DT97-4290, a moderately resistant cultivar. The genotypes identified as having moderate resistance for each of the three year could be useful as a source for resistance in developing high resistant soybean genotypes.