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ARS Home » Midwest Area » East Lansing, Michigan » Sugarbeet and Bean Research » Research » Publications at this Location » Publication #351862
Research Project: Genetic Characterization for Sugar Beet Improvement

Location: Sugarbeet and Bean Research

Title: Fungicide sensitivity of Alternaria spp. causing Alternaria leaf spot on sugarbeet in Michigan

Author
item ROSENZWEIG, N - Michigan State University
item Hanson, Linda
item PRATT, D - Michigan Sugar Company
item SAMOHANO, P - Michigan State University

Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 6/1/2017
Publication Date: 12/1/2017
Citation: Rosenzweig, N., Hanson, L.E., Pratt, D., Samohano, P. 2017. Fungicide sensitivity of Alternaria spp. causing Alternaria leaf spot on sugarbeet in Michigan. Phytopathology. 107:S5.176.

Interpretive Summary:

Technical Abstract: Alternaria leaf spot (ALS), caused by Alternaria spp., can occur wherever sugarbeet is grown. Infection by Alternaria spp. and disease management has historically been considered a minor issue in sugarbeet production in the US. Recently, increased incidence and severity of ALS has been observed in MI at levels high enough to have the potential to cause yield loss due to defoliation. The objectives of this monitoring program were to: 1. collect ALS-infected sugarbeet leaves from commercial production fields in eastern Michigan; and 2. determine the sensitivity of the populations of Alternaria spp. to fungicides in three classes, including: demethylase inhitor fungicides [difenoconazole (DA), fenbuconazole (FA), flutriafol (FL), prothioconazole (PA), and tetraconazole (TA)]; quinone outside inhibitor fungicides (pyraclostrobin, PS); and organo-tins (tri-phenyl tin OH, TPTH). Leaves with symptoms of ALS were sampled from sugarbeet fields in east-central Michigan. Mono-conidial isolates were obtained to determine sensitivity to each fungicide above. A spiral gradient dilution method was used to determine and estimate the fungicide concentration which caused a 50% inhibition of fungal growth (EC50) in vitro for all isolates. A total of 143, 140, 13, 131, 143, 147 and 144 isolates were screened against DA, FA, FL, PA, PS, TPTH, and TA respectively and the mean EC50 values were 3.0, 70.9, 46.8, 52.4, 62.0, 16.4 and 87.4 for DA, FA, FL, PA, PS, TPTH, and TA respectively.