Susceptibility and Yield of Forty-four Soybean Varieties to the Southern Root-knot Nematode, 2023

by Michael Emerson, Brandon Baker, Katherine Brown, and Travis Faske - November 8, 2023

If you have any questions please contact tfaske@uada.edu

The southern root-knot nematode (Meloidogyne incognita) is the most yield-limiting plant-pathogenic nematode that affects soybean production in the Mid-South. It is found in nearly all soybean counties in Arkansas and can cause significant (>70%) grain yield losses when a susceptible variety is planted in a field with a high population density of southern root-knot nematode (RKN).  Forty-four commercially available soybean varieties marketed as suitable for production in southern RKN fields were screened.   Varieties were divided into 3 experiments (Table 1 to 3) based on maturity group.  Varieties were planted in a randomized complete block design with four replications per entry.  Plots consisted of 4 rows, 30 ft long, spaced 30 in. apart, separated by a 5-ft fallow alley.  Plots were planted on 27 May at a seeding rate of 150,000 seeds/A.  Six root systems were arbitrarily sampled at the R5 growth stage from non-harvest rows of each plot to assess southern RKN host susceptibility.  The final nematode population (Pf) density averaged 916 second-stage juveniles/100 cm³ soil at harvest for susceptible checks across experiments.  The density would be considered severe for soybean production in Arkansas. The two center rows of each plot were harvested on 16 Oct.  These results and those on the UA variety testing website can be helpful for variety selection for the 2024 cropping season.  

Reports from previous trials (2016 to 2022)    are available on the UADA website.

What else is important: Overall, the severity (percent of root system galled) was better than last year, which indicates a good screen.  Keep in mind that varieties may not provide the same yield or disease severity rating in field soils that have a greater percent sand and are drought stressed.  However, by selecting a variety that is less susceptible will ensure a greater yield than a more susceptible one in a nematode infested field. For example, “Invictis B4921E” would likely have a lower gall rating and grater yield than “Delta Grow DG4880 GLY”, but not “Progeny P4806XFS”, if planted in the same field. Finally, consult the cross-reference guide for soybean varieties to ensure different varieties selected are not the same genetics.  

Table 1. Field performance of several MG IV soybean varieties in a southern root-knot nematode infested field. The soil texture was a sandy loam soil (59% sand, 36% silt, and 5% clay).  (Pf = 873 second-stage juveniles/100 cm³ soil.)

Table 2. Field performance of several MG IV soybean varieties in a southern root-knot nematode infested field, experiment 2. The soil texture was a sandy loam soil (49% sand, 46% silt, and 5% clay). (Pf = 455 second-stage juveniles/100 cm³ soil.)

Table 3. Field performance of several MG V soybean varieties in a southern root-knot nematode infested field, experiment 3. The soil texture was a sandy loam soil (59% sand, 36% silt, and 5% clay).  (Pf = 1420 second-stage juveniles/100 cm³ soil.)

Acknowledgments:  The Lonoke Extension Plant Pathology Program would like to thank all seed companies that provided seed, Fletcher Farms for providing land to conduct these trials and the Arkansas Soybean Promotion Board for funding this project.