Jonathan Karl Corser (he/him/his)
Mississippi State University, Delta Research and Extension Center
Shaw, Mississippi, United States
Tom W. Allen
Extension/Research Professor
Delta Research & Extension Center, Mississippi State University
Stoneville, Mississippi, United States
Seung-Joon Ahn
Mississippi State University
Starkville, Mississippi, United States
Nicholus Tadlock
Mississippi State University, Delta Research and Extension Center
Greenville, Mississippi, United States
April Reynolds
Mississippi State University
Greenville, Mississippi, United States
Stephanie Johnson
Mississippi State University, Delta Research and Extension Center
Leland, Mississippi, United States
Tessie Wilkerson
Mississippi State University, Delta Research and Extension Center
Stoneville, Mississippi, United States
Charcoal rot (CR) of soybean, caused by Macrophomina phaseolina (Mp), can be annually important by limiting profitability of Mississippi soybean. In general, CR can be most severe during hot and dry years. Over the last 20 years, CR has resulted in estimated yield losses of 11 million metric tons, across the southern U.S. The objective of this research was to quantify the concentration of Mp within commercially available soybean cultivars. The field experiments were conducted during 2023 and 2024 and consisted of the commercial cultivars contained in the MSU Official Variety Trial program for each respective year. The trial consisted of a non-irrigated study with each cultivar planted in four row plots, two rows inoculated with Mp-infested pearl millet, applied in-furrow at planting, and two rows non-inoculated. Each cultivar was replicated three times. Entire root systems from five plants were collected representing inoculated and non-inoculated rows at R6.5, dried at ambient temperature for 35 days, and homogenized in a Wiley mill. In preparation for qPCR, genomic DNA (gDNA) was extracted from samples and diluted to 10 ng/μl. Amplification was performed using SYBR green reagents and a set of Mp species-specific primers. On average, inoculated samples of the early maturity group (MG) IV (n=123/inoculation type) accumulated 29.4 ng/μl of gDNA, while non-inoculated samples accumulated 19.7 ng/μl. The MG IV late (n=111/inoculation type) inoculated samples recorded an average gDNA concentration of 18.6 ng/μl, while non-inoculated samples recorded 15.4 ng/μl of gDNA.