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Submitted to: Crop Protection
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 1/14/2017 Publication Date: 1/15/2017 Citation: Roberts, D.P., Mckenna, L.F., Buyer, J.S. 2017. Consistency of control of damping-off of cucumber is improved by combining ethanol extract of Serratia marcescens with other biologically based technologies. Crop Protection. 96:59-67. http://dx.doi.org/10.1016/j.cropro.2017.01.007. Interpretive Summary: Soilborne plant pathogens cause diseases that result in major economic losses to farmers in the United States. Biological control measures for these diseases need to be developed for conventional crop production systems due to environmental problems associated with existing chemical controls. We tested ethanol extracts of Serratia marcescens N4-5, when applied as a cucumber seed treatment, for control of damping-off of cucumber caused by Pythium ultimum in four soils that differed in biotic and abiotic characteristics. Plant stand associated with this treatment was similar to that of seeds treated with the chemical pesticide Thiram in two sandy loam soils. This N4-5 ethanol extract did not provide consistent disease control in a loam soil and the fourth soil was not conducive to disease. A combination treatment containing seed treatment with this N4-5 ethanol extract and a drench containing Trichoderma virens GL21 controlled disease in all soils at all levels of pathogen inoculum used. In some cases plant stand associated with this treatment was significantly greater than that resulting from individual application of N4-5 ethanol extract or T. virens GL21. Data presented here indicate that strategic combinations of biologically based disease control tactics can increase consistency of performance over multiple soils that vary in biotic and abiotic characteristics. This information will be useful to scientists devising strategies for control of soilborne plant pathogens. Technical Abstract: Environmentally friendly disease control tactics are needed that are consistently effective in soils that vary with regard to their biotic and abiotic components. An ethanol extract of Serratia marcescens N4-5, when applied as a cucumber seed treatment, effectively suppressed damping-off of cucumber caused by Pythium ultimum in two natural sandy loam soils and a natural sand soil. Plant stand associated with this treatment was similar to that of seed treated with the chemical pesticide Thiram. The N4-5 ethanol extract did not consistently provide disease suppression in a natural loam soil. A combination treatment containing seed treatment with this N4-5 ethanol extract and a drench containing Trichoderma virens GL21 improved disease control performance relative to individual application of both of the treatment components. Plant stand associated with this combination treatment was significantly greater than the no treatment control in all natural soils at all levels of pathogen inoculum used. In some cases plant stand associated with this treatment was significantly greater than that resulting from individual application of N4-5 ethanol extract or T. virens GL21. Data presented here indicate that strategic combinations of biologically based disease control tactics can increase consistency of performance over multiple soils that vary in biotic and abiotic characteristics. |
