Field Performance of One Hundred Five Soybean Varieties Against the Southern Root-knot Nematode and Frogeye Leaf Spot, 2025
A comprehensive disease screening program has been conducted by the University of Arkansas System, Division of Agriculture, Extension Plant Pathology since 1990, thanks to support by the Arkansas Soybean Promotion Board. A combination of field nurseries and greenhouse experiments are used to evaluate all varieties that are entered in the Official Variety Testing Program to major diseases of concern in Arkansas. The diseases evaluated and reported here during the 2025 cropping season was the southern root-knot nematode (Meloidogyne incognita) and frogeye leaf spot (caused by Cercospora sojina). Some 105 soybean varieties were planted on 3 June in single row, 11-ft long plots at 150,000 seeds per acre in a silt loam soil (42% sand, 52% silt, and 6% clay) field near Kerr, AR.
The final nematode population (Pf) density averaged 211 second-stage juveniles (J2)/100 cm3 soil at harvest across the experiment. This density is considered severe for soybean production in Arkansas. The post-harvest threshold for southern root-knot nematode on soybean in Arkansas is 60 J2 per 100 cm3 soil. Weather conditions were favorable for frogeye leaf spot and disease severity was greater than previous years. Southern stem canker is also part of the comprehensive disease screening project but not included in this report.