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Soybean mosaic virus (SMV) is an important viral disease of soybean [Glycine max (L.) Merr.] and causes a drastic reduction of seed yield and quality. Soybean mosaic virus isolates can be classified into one of seven strain groups, G1 through G7. Three loci with SMV resistance alleles Rsv1, Rsv3, and Rsv4 have been reported so far. Each locus contains multiple alleles: nine alleles at Rsv1, three alleles at Rsv3, and two alleles at Rsv4. Soybean cultivars Corsica (PI 559931) and Beeson (PI 548510) exhibit different patterns of response to SMV strains than differential cultivars with known genes. The objective of this study was to investigate the inheritance and allelism of resistance genes in Corsica and Beeson. To examine the inheritance of SMV resistance, Corsica and Beeson were crossed with the susceptible cultivar Essex, and the F2 and F3 progenies were inoculated with a G7 isolate. To identify the allelic relationship of genes in Corsica and Beeson with known SMV resistance loci, they were crossed with PI 96983 (Rsv1), ‘L29’ (Rsv3), and V94‐5152 (Rsv4), and their F2 plants and F2:3 lines were inoculated with G7. A serological tissue blotting immunoassay (TBIA) was used to confirm the presence or absence of the virus in the inoculated plants. Molecular markers were used to confirm the phenotypic data. The results showed a monogenic dominant resistance in Corsica, with the resistant gene located at the Rsv1 locus. Beeson also contains a single dominant gene for SMV resistance, but the gene is located at the Rsv4 locus. Both genes in Corsica and Beeson confer a different SMV reaction pattern than other reported alleles at the same loci. Therefore, we propose the new symbols of Rsv1‐c for the resistant gene in Corsica and Rsv4‐b for the resistant gene in Beeson. The results from the genetic study were confirmed by the molecular markers and TBIA. The information from this study can be used for parent selection by breeders in cross breeding and gene pyramiding.

Nutrient‐rich biochar produced from animal wastes, such as poultry litter, may increase plant growth and nutrient uptake although the role of direct and indirect mechanisms, such as stimulation of the activity of mycorrhizal fungi and plant infection, remains unclear. The effects of poultry litter biochar in combination with fertilizer on mycorrhizal infection, soil nutrient availability and corn (Zea mays L.) growth were investigated by growing corn in a loam soil in a greenhouse with biochar (0, 5 and 10 Mg/ha) and nitrogen (N) and phosphorus (P) fertilizer (0, half and full rates). Biochar did not affect microbial biomass C or N, mycorrhizal infection, or alkaline phosphomonoesterase activities, but acid phosphomonoesterase activities, water‐soluble P, Mehlich‐3 Mg, plant height, aboveground and root biomass, and root diameter were greater with 10 Mg/ha than with no biochar. Root length, volume, root tips and surface area were greatest in the fully fertilized soil receiving 10 Mg/ha biochar compared to all other treatments. The 10 Mg/ha biochar application may have improved plant access to soil nutrients by promoting plant growth and root structural features, rather than by enhancing mycorrhizal infection rates.

Despite many decades of education and refining land-use practices, accelerated stream bank erosion is still prevalent in the United States. Eroding stream banks produce a sediment load to the riverine system and can cause reduced water quality as a result of increased suspended sediment. As total maximum daily loads (TMDLs) for water bodies impaired by turbidity or suspended sediments become more numerous, a simple, in situ field technique will be needed to estimate the bulk density of readily erodible stream bank material so that reasonably accurate sediment loading rates can be estimated. In this study, the excavation/polyurethane-foam technique for estimating total bulk density was applied to vertically exposed alluvium with high coarse-fragment content. Though not previously attempted in vertically exposed alluvium with high coarse-fragment content, the excavation/polyurethane-foam technique appears to provide a reasonably accurate estimate of the total and soil (<2-mm size fraction) bulk density from vertically exposed, alluvial deposits with high coarse-fragment content (i.e., >70%) along eroding stream banks. Obtaining bulk density estimates using this method would facilitate calculation of sediment loading rates to riverine systems with actual field data.

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