Hartman, G., Pawlowski, M. L., Herman, T., and Eastburn, D. M. 2016. Organically grown soybean production in the USA: Constraints and management of pathogens and insect pests. Agronomy 2016, 6(1), 16; doi:10.3390/agronomy6010016.
Soybean is the most produced and consumed oil seed crop worldwide. In 2013, 226 million metric tons were produced in over 70 countries. Organically produced soybean represents less than 0.1% of total world production. In the USA, the certified organic soybean crop was grown on 53 thousand ha or 0.17% of the total soybean acreage in the USA (32 million ha) in 2011. A gradual increase in production of organically grown soybean has occurred since the inception of organic labeling due to increased human consumption of soy products and increased demand for organic soybean meal to produce organic animal products. Production constraints caused by pathogens and insect pests are often similar in organic and non-organic soybean production, but management between the two systems often differs. In general, the non-organic, grain-type soybean crop are genetically modified higher-yielding cultivars, often with disease and pest resistance, and are grown with the use of synthetic pesticides. The higher value of organically produced soybean makes production of the crop an attractive option to some farmers. This article reviews production and uses of organically grown soybean in the USA, potential constraints to production caused by pathogens and insect pests, and management practices used to reduce the impact of these constraints.
Xiang, Y., Scandiani, M. M., Herman, T. K., and Hartman, G. L. 2015. Optimizing conditions of a cell-free toxic filtrate stem cutting assay to evaluate soybean genotype responses to Fusarium species that cause sudden death syndrome. Plant Disease 99:502-507.
Cell-free toxic culture filtrates from Fusarium virguliforme, the causal fungus of soybean sudden death syndrome (SDS), cause foliar symptoms on soybean stem cuttings similar to those obtained from root inoculations in whole plants and those observed in production fields. The objectives of this study were to (i) optimize the production conditions for F. virguliforme cell-free toxic culture filtrates and the incubation conditions of the stem cutting assay used to test the toxicity of the cell-free toxic culture filtrates, and (ii) use the optimized assay and a whole plant root inoculation assay to compare four SDS-causing isolates on a panel of selected soybean genotypes. Area under the disease progress curve (AUDPC) values were highest (P = 0.05) when cuttings were immersed in culture filtrate of fungus grown in soybean dextrose broth, in filtrate produced from the fungus grown for 18 or 22 days, and when stem cuttings were incubated at 30°C. AUDPC values and shoot dry weights from the whole plant root inoculations and the AUDPC values from the stem cutting assay differed (P < 0.05) among nine soybean genotypes tested with F. virguliforme and F. tucumaniae isolates, and the AUDPC values from the two assays were positively correlated (r = 0.44 at P < 0.0001).
Xiang, Y., Herman, T.K., Hartman, G.L. 2014. Using soybean milk to culture soybean pathogens. Advances in Microbiology. 4:126-132.
Liquid and semi-solid culture media are used to maintain and proliferate bacteria, fungi, and Oomycetes for research
in microbiology and plant pathology. In this study, a comparison was made between soybean milk medium,
also referred to as soymilk, and media traditionally used for culturing soybean pathogens to determine if
soymilk medium was an effective medium for growth of Colletotrichum truncatum, Fusarium virguliforme, Macrophomina
phaseolina, Passalora sojina, Phomopsis longicolla, Phytophthora sojae, Pythium irregulare, Rhizoctonia solani, and Sclerotinia sclerotiorum. Based on radial mycelial colony growth rates, C. sojina grew significantly (P < 0.05) faster on soymilk dextrose agar (SDA) than on V-8 agar, and C. truncatum and F. virguliforme grew significantly (P < 0.05) faster on SDA than potato dextrose agar (PDA). Significantly (P < 0.001) greater masses of sclerotia were produced by S. sclerotiorum grown on SDA as compared to PDA. Soymilk used with agar or used alone as a broth may be an option for replacing more expensive processed culture media.
Hartman, G.L., West, E.D., and Herman, T.K. 2011. Crops that feed the World 2. Soybean—worldwide production, use, and constraints caused by pathogens and pests. Food Security 3:5-17.
Hill, C.B., Crull, L., Herman, T.K., Voegtlin, D.J. and Hartman, G.L. 2010. A new soybean aphid (Hemiptera: Aphididae) biotype identified. J. Economic Entomology 103:509-515.
Hobbs, H. A., Herman, T. K., Slaminko, T. L., Wang, Y., Nguyen, B. T., McCoppin, N. K., Domier, L. L. and Hartman, G. L. 2010. Occurrences of soybean viruses, fungal diseases, and pests in Illinois soybean rust sentinel plots. Online. Plant Health Progress doi:10.1094/PHP-2010-0827-01-BR.
After soybean rust was confirmed in soybean in the USA, sentinel plots were established in 26 states to monitor its spread. Funding for establishing, sampling, and monitoring the plots came from the USDA, national, regional, and state soybean commodity boards, and state departments of agriculture, extension services, and universities. The presence of sentinel plots for soybean rust monitoring provided the potential for reducing the time and expense of extensive statewide travel for collection of soybean leaf samples for monitoring the incidence of other foliar diseases of soybean in Illinois.