2019 trials rate variety performance vs. southern root-knot nematodes

• By Michael Emerson and Travis Faske •

nematode galling
Southern root-knot nematode galling on soybean roots — photo courtesy University of Arkansas

The southern root-knot nematode (Meloidogyne incognita) is the most important yield-limiting plant-pathogenic nematode that affects soybean production in the Mid-South. It is found in nearly all soybean-producing counties in Arkansas and can cause significant (>70%) yield loss when the wrong soybean variety (i.e. susceptible) is planted in fields with a high population density of root-knot nematodes.

During the 2019 season, the Lonoke Extension Plant Pathology Program selected 56 soybean varieties that were divided into five experiments based on herbicide technologies and maturity groups. Varieties were replicated four times, and eight root systems from each plot were sampled for the percent of root system galled at R4-R5 growth stage.

The final nematode population densities collected at harvest ranged from 154-4,192 second-stage root-knot nematode juveniles (J2)/100 cm3 soil, which would be a moderate to severe nematode threshold in Arkansas.

As a general rule, soybean varieties with the lowest gall rating had the greatest yield. Soybean varieties with an average of less than 4% of root system galled were considered resistant, especially when compared to those with the greatest galling percentage.

Field performance of soybean varieties from previous trials (2016 and 2017) can be found on the UA Research Series website. These results and those on the UA variety testing website can be helpful for variety selection for the 2020 cropping season.

View the performance results by downloading the pdf  “2019 Selected Soybean in RKN Field

Michael Emerson is a University of Arkansas program associate at Lonoke. Dr. Travis Faske is Extension plant pathologist at Lonoke. He can be reached at tfaske@uaex.edu.

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