Sudden death syndrome (SDS) of soybean (Glycine max [L.] Merr.) is a soilborne disease of increasing importance in high‐yield environments. This study was conducted to determine which combinations of soil fertility parameters and soybean cyst nematode (Heterodera glycines Ichinoe) (SCN) second stage juvenile (J2) population levels were associated with SDS disease severity. Also, the effect of SDS disease severity on leaf nutrient content and on soybean yield and seed germination were determined. These studies were conducted at the Pine Tree Station, in Colt, on a Crowley silt loam (fine, montmorillonitic, thermic Typic Albaqualfs) over 3 yr with the soybean cultivar Lee 74. Soil factors associated with SDS were increased levels of soil available P, electrical conductivity (soluble salts), organic matter, and exchangeable Na, Ca, and Mg. Decreased levels of leaf N, Mg, Cu, and Mn and increased levels of leaf Ca were related to increased levels of SDS severity. Sudden death syndrome severity was negatively correlated with yield in 2 of 3 yr and with seed quality in 1 of 2 yr. Soybean cyst nematode second stage juvenile population density decreased as SDS severity increased in the study relating soil and leaf nutrient levels fo SDS. This may reflect a decrease in the ability of a diseased root system to support nematode reproduction. In the yield studies, however, SCN was negatively correlated to yield and positively correlated to SDS in 1 of 2 yr. Soybeans grown in high production environments of increased soil fertility and irrigation appear to be more susceptible to SDS. Sudden death syndrome affects yields by a reduction in seed size and number and may, under the proper environmental conditions, affect seed germination. The role of SCN in SDS is still unclear.
Research Question
Sudden death syndrome (SDS) is an important soilborne disease of soybean in parts of the South and Midwest. The disease is associated with high‐yield production'environments. This study compared the effects of soil and plant chemical factors on SDS severity and the relationship between SDS severity on yield and seed germination.
Literature Summary
Sudden death syndrome usually appears after flowering in vigorously growing, well‐watered soybeans, and is often associated with the soybean cyst nematode (SCN). Losses due to this disease vary greatly, but can be severe. Like other soilborne diseases, SDS distribution usually is aggregated in the field. Disease aggregation as well as inoculum distribution is strongly influenced by the soil environment. Since SDS is associated with high‐yield production environments, soil chemical factors may have a strong effect on SDS severity as they do with other soil‐borne diseases. While SDS appears to affect yield, the relationship of disease severity and yield has not been demonstrated nor has the effect of SDS severity on seed germination been determined.
Study Description
The study was conducted at the Pine Tree Station, Colt, AR, in a field with a history of SDS. Soil and plant samples were collected,...