Reaction of Soybean Cyst Nematode Resistant Sources to Root Knot Nematode, Reniform Nematode and Frogeye Leaf Spot.

Soybean cyst nematode (SCN) Heterodera glycines (Ichinohe), southern root knot nematode [Meloidogyne incognita (Kofoid & White) Chitwood] and reniform nematode [Rotylenchlus reniformis (Linford and Oliveria)] are common in southern US fields. Each of these nematodes individually or collectively causes significant economic losses to field grown soybean [Glycine max (L.) Merr.] and other crops.  Soybean cultivars with resistance to all three nematode species are desirable and would reduce losses in farmer’s fields. There are about 120 G. max plant introductions (PIs) from the US soybean germplasm collection that have shown resistance to one or more SCN populations (HG types). In addition to SCN resistance, some sources have shown resistance to root knot (RKN) and/or reniform nematodes (RN). Many of these SCN resistant PI lines have not been screened to either RKN or RN. The purpose of this research was to collectively evaluate the 120 SCN resistant sources to RKN, RN and frogeye leaf spot (FELS) caused by Cercospora sojina K. Hara.  About half of the PIs or 64 out of the 120 SCN resistant sources showed resistance or moderate resistant to RKN. Out of the 64 SCN resistant sources with RKN resistance, 27 showed resistance to RN.  Of these 27, 13 SCN resistant PIs were resistant to all three pests- RKN, RN and FELS. There were 14 PIs with SCN and RKN resistance that showed resistance to FELS, but were susceptible to RN.  This information will be useful to soybean breeders and other researchers who want to study genotypes or develop soybean cultivars with cross resistance to multiple nematode species and frogeye leaf spot.