Soil and Plant Factors Associated with Sudden Death Syndrome of Soybean

Abstract

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,...

Soybean Disease Monitoring with Leaf Reflectance

“…For example, the chlorophyll concentration peaked out at 85 DAP in susceptible plants under SS treatment compared to 100 DAP under SDS alone, and 105 DAP under SCN alone in Essex, a cultivar susceptible to both SDS and SS. Our results agree with similar observations made by Rupe et al [10]. …”

“…glycines (F. virguliforme or FV). The symptoms start with spot yellowing and drying in lower leaves, and eventually spread to the top leaves resulting in total wilting of all the leaves while the shoots are still green [10,11]. Without intensive crop scouting, SDS is difficult to detect in the early stages of infection because the disease starts from the lower leaves.…”

Genetic analysis infers Dt loci underlie resistance to Fusarium solani f. sp. glycines in indeterminate soybeans

“…Although the loci can be readily selected in northern germplasm for the apparent improvement of resistance to SDS the effect is derived from morphology, maturity and determinacy. Resistance in Minsoy approximates to a tolerant response to SDS (Rupe et al 1994(Rupe et al , 1995. The loci are not in the same intervals as loci shown to be involved in plant defense (Iqbal et al 2002a(Iqbal et al , b, 2005 or to contain defense genes (Shopinski et al 2003.…”

“…Correlations between field and greenhouse resistance are significant (Stephens et al 1993a;Njiti et al, 2001). Correlations of SDS resistance with planting date and morphological traits such as growth habit, maturity, leaf morphology and stem morphology are significant (Gibson et al 1994;Rupe et al 1994;Rupe and Gbur 1995;Njiti et al 1996Njiti et al , 2002. Therefore, resistance gene mapping studies must be carefully designed to exclude these sources of variability (Hnetkovsky et al 1996;Lightfoot et al 2005).…”

Sudden death syndrome - a growing threat of losses in soybeans.

“…There are numerous factors that affect SDS such as; effects of herbicides on metabolic activities and growth of host and pathogens and increase in soil-borne diseases as a result of herbicidepathogen interaction [3], interaction between F. virguliforme and cyst nematodes [26,99,103,143,144], biotic and abiotic factors [98], irrigation and cyst nematodes [70], irrigation and soil compaction [20], tillage [117,127,128,135], inoculum density [28], isolates and inoculum rate [31], genetic structure and variation in aggressiveness of F. virguliforme [66], soil variables including fertility parameters [105,112], soil temperature [29,113], water matric potential in soil [113], relation of sand content, soil pH, and soil nutrients [109], cultivars [39,89,101,105,127,135], genetic architecture of soybean [156], planting date [39,52,135], crop rotation and crop sequences [93,104,142], root system [91], plant age [29,30], early infection and xylem colonization [83,86,154], biochemical response of soybean roots …”