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ARS Home » Southeast Area » Stoneville, Mississippi » Crop Genetics Research » Research » Publications at this Location » Publication #339044
Title: Coupling Spore Traps and Quantitative PCR Assays for Detection of Cercospora sojina, the Causal Agent of Soybean Frogeye Leaf Spot

Author
item LIN, BINBIN - University Of Tennessee
item YOUNG, HEATHER - University Of Tennessee
item YU, HAO - University Of Tennessee
item Mengistu, Alemu

Submitted to: Southern Soybean Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 3/7/2017
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Frogeye leaf spot (FLS), caused by Cercospora sojina Hara, is a common disease of soybean in most soybean-growing countries of the world. Significant yield losses of soybean (10–60%) have been attributed to FLS under hot and humid growing conditions. We present a novel trapping approach using Vaseline coated slides placed at a 45° angle within a passive, wind-vane spore trap used in combination with a rapid molecular method to detect the presence of wind-blown inoculum. Spore traps were run from mid-July to early October 2015 at the Milan Research and Education Center in Tennessee. Preliminary data from 2015 suggested that there were two major peaks of inoculum during the 2015 season. In 2016, multiple spore traps were deployed at 3 locations: (1) non-treated tilled and no-till research plots in Milan, TN sampled weekly, (2) on the edge of large soybean sentinel plots in 4 different counties in TN sampled weekly, and (3) on the edge of a small plot research trial in Jackson, TN sampled twice a week. DNA per spore trap was extracted from Vaseline coated slides and qPCR was conducted using species specific primers/probes to estimate the number of spores based on a standard curve developed from known spore concentrations. FLS severity ratings were recorded at each reproductive growth stage from R1 (first bloom) through R7 (physiological maturity) using percent leaf area affected at locations 1 and 2. Comparing data from spore traps located in Jackson, TN there was no significant difference between sampling twice per week or once per week. Additionally, there was no significant difference between spore amounts collected from tilled and no-till plots, just as disease severity was not significantly different between tilled and no-till plots. Spore trap data collected from different counties varied in trends and resulted in several major peaks of inoculum during the season, most likely influenced by variety susceptibility to FLS, field history, and weather conditions. In combination with disease-conducive weather forecasting, variety and field history information, application of the assays may be helpful to time fungicide applications for disease management.