Effect of Crop Rotation on Soybean in a Field Infested with Meloidogyne arenaria and Heterodera glycines.

The effect of previous crops--soybean (Glycine max) or corn (Zea mays)--and aldicarb (2.2 kg a.i./ha) on yield and nematode numbers at harvest for soybean cultivars with various combinations of nematode resistance was determined in a sandy loam soil infested with Meloidogyne arenaria race 2 and Heterodera glycines races 3 and 4 at Elberta, Alabama, in 1987. Cultivars had an effect on yield and nematode numbers (P = 0.01), as did the interaction of previous crop and cultivar. The nematicide treatment x cultivar interaction was significant for yield, and the three-way interaction was significant for numbers of M. arenaria. A previous crop of corn had no effect on M. arenaria numbers, but it reduced numbers of H. glycines from 93 to 25 J2/100 cm(3) of soil and increased soybean yield from 1,963 to 2,560 kg/ha. Aldicarb reduced M. arenaria numbers from 230 to 186 J2/100 cm(3) soil and increased yield from 2,062 to 2,460 kg/ha but it had no effect on H. glycines numbers. Rotation with corn was an effective control measure for H. glycines and enhanced the yields of H. glycines-susceptible cultivars.