Response of soybean sudden death syndrome to tillage and cultivar

Sudden death syndrome (SDS), caused by Fusarium, solani f. sp. glycines, is a season-long root disease of soybean (Glycine max) with foliar symptoms beginning in late vegetative and early reproductive stages of plant growth. The disease has been reported in most soybean-growing regions of the United States of America and the world. Previous research found that SDS was less severe in areas that were subsoiled when compared with those with no-till. The objectives of the current study were to determine (i) if cost-effective tillage practices, i.e., chisel plowing and disk tillage, can be efficient in reducing SDS and (ii) if cultivars with a range of SDS resistance or susceptibility respond differently in SDS expression across various tillage practices. In the fall of 2000 and 2001, plots were established in a field with a history of severe SDS and with a soil type consisting of an Armiesburg silty clay loam. The experiment was organized in a split-plot design with four replications. Main plots were tillage (chisel tillage, disk tillage, and no tillage), and subplots were cultivars randomized in main plots. Twelve cultivars were selected based on resistance or susceptibility to SDS. In 2000, chisel tillage reduced the area under the foliar disease progress curve (AUFDPC) when compared with no-till or disk tillage. In 2001, both chisel and disk tillage reduced AUFDPC similarly when compared with no-till. In 2000, the rate of root infection by the fungus, that is, the area under the root colonization progress curve (AURCPC), was higher in both disk- and chisel-tillage treatments than in no-tillage treatments. In 2001, higher rates of root infection occurred with chisel tillage compared with disk tillage and no-till. Among the cultivars, foliar disease ratings, AUFDPC, and soybean yield differed, but there were no differences in the AURCPC.