Inoculation methods under greenhouse conditions for evaluating soybean resistance to sudden death syndrome

The objectives of this work were to evaluate two greenhouse screening methods for sudden death syndrome (SDS) and to determine which one is best correlated with fi eld resistance of soybean genotypes. The evaluations were done with three sets of genotypes that were classifi ed as partially resistant, intermediate, and susceptible to SDS based on previous fi eld evaluations. These three sets were independently evaluated for greenhouse SDS reactions using cone and tray inoculation methods. Plants were infected using grains of white sorghum [Sorghum bicolor (L.) Moench] infested with Fusarium solani f. sp. glycines. Foliar symptom severity was rated 21 days after emergence. The cone and fi eld SDS ratings were signifi cantly correlated and ranged from 0.69 for set 1 to 0.51 for set 3. Correlations of SDS ratings of genotypes between fi eld and greenhouse tray ratings were signifi cant for set 1 and not signifi cant for set 2. The cone method showed the highest correlation with fi eld results and is recommended to screen soybean genotypes for SDS resistance.