Management of Xiphinema americanum and Soybean Severe Stunt in Soybean Using Crop Rotation.

Soybean severe stunt (SSS), caused by the Soybean severe stunt virus (SSSV), is a soilborne virus disease affecting soybean (Glycine max) first described in Delaware in 1988. Lack of breeding programs directed at incorporating resistance to SSSV in new cultivar releases necessitated alternative methods of SSS control. The effect of crops in 2-year rotations on the dagger nematode (Xiphinema americanum), the putative nematode vector of SSSV, and SSS severity were examined. Two years of continuous corn or grain sorghum, wheat followed by 'HT-5203' soybean, or 2-year fallow, reduced both dagger nematode density in the soil and SSS severity. Crop rotation to the SSSV-tolerant HT-5203 soybean as a single crop for 2 years increased dagger ematode populations and SSS severity. Greenhouse studies indicated that corn, wheat, marigold, castor, and fallow treatments reduced dagger nematodes the most after 14 weeks compared with 'Essex' and HT 5203 soybean.