Location: Sustainable Agricultural Systems Laboratory
2018 Annual Report
Accomplishments
1. Seed treatment improves control of cucumber disease. Controlling soil-borne plant pathogens with methyl bromide alternatives is promising but can provide inconsistent performance in different soils. ARS researchers in Beltsville, Maryland, demonstrated that a combination treatment containing ethanolic extract of the bacterium Serratia marcescens and the plant-beneficial fungus Trichoderma virens isolate GL21 improved disease control performance relative to individual application of these treatment components in several soils. Strategies such as this that improve efficacy and consistency of disease control will enhance grower acceptance of biologically based disease control treatments.
2. Controlling soil-borne pathogens in conventional and organic crop production systems. ARS researchers in Beltsville, Maryland, demonstrated that seed treatment with cell-free ethanolic extract of the bacterium Serratia marcescens was as effective as the commercial pesticide Thiram. These same researchers have determined that this ethanolic extract contains large amounts of the compound prodigiosin and that treating seeds with purified prodigiosin controlled the cucumber disease “damping-off.” Prodigiosin is potentially useful for controlling damping-off disease on cucurbits in conventional and organic production systems.
3. Thymol acetate is a commercially viable plant-based fungicide. ARS scientists in Beltsville, Maryland, screened thymol, the key component of thyme oil, and its derivatives for fungicidal activity against the plant pathogen Rhizoctonia solani, which is one of the major pathogens causing the disease “damping-off” on seedlings. Of six thymol derivatives, thymol acetate has superior disease control efficacy and low phytotoxity. Compounds such as thymol acetate could provide environmentally friendly control of this important soil-borne plant pathogen in conventional and organic cropping systems.
Review Publications
Lakshman, D.K., Kamo, K.K. 2018. First report of lily root rot caused by Thantephorus cucumeris AG 2-1 in the United States. Plant Disease. https://doi.org/10.1094/PDIS-09-17-1497-PDN.
Chauhan, K.R., Le, T.C., Chintakunta, P., Lakshman, D.K. 2017. Phyto-fungicides: Structure activity relationships of the thymol derivatives against Rhizoctonia solani. Journal of Agricultural Chemistry and Environment. 6:175-185.
Lakshman, D.K., Chauhan, K.R., Pandey, R., Choudhury, B. 2017. Evaluation of plant-based antifungal chemicals and control of damping-off caused by Rhizoctonia solani. Biopesticides International. 13(1):21-34.
Hu, X., Qin, L., Roberts, D.P., Lakshman, D.K., Gong, Y., Maul, J.E., Xie L., Yu, C., Li, Y., Hu, L., Liao, X., Liao, X. 2017. Characterization of mechamisms underlying degradation of sclerotia of Sclerotinia sclerotiorum by Aspergillus aculeatus Asp-4 using a combined qRT-PCR and proteomic approach. BMC Genomics. 18:674. https://doi.org/10.1186/s12864-017-4016-8.
Roberts, D.P., Mattoo, A.K. 2018. Sustainable Agriculture - Enhancing environmental benefits, food nutritional quality and building crop resilience to abiotic and biotic stresses. Agriculture. 8:8. https://doi.org/10.3390/agriculture8010008.
