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Relation and occurrence of Fusarium virguliforme, Macrophomina phaseolina, and Heterodera glycines in Tennessee

Autumn McLaughlin: University of Tennessee

<div>Soil borne pathogens such as <em>Fusarium virguliforme</em> (FG), <em>Macrophomina phaseolina</em> (MP), and <em>Heterodera glycines</em> (HG) can reduce soybean (<em>Glycine max</em>) yield by damaging the roots and vascular system and causing plant death. Due to the importance of these pathogens, we aim to evaluate their occurrence across Tennessee. In the fall of 2017, 24 soil samples and 14 root samples were collected from 4 different counties. Soil probes were used to collect 15 cm. deep soil cores targeting the root zone of the previous crop. Soil was elutriated and used to evaluate HG eggs/100 cc soil. Colony forming units (CFU) were evaluated to quantify FG and MP using 0.05g and 0.005g of root samples, respectively; and 1g of soil. Soil was dried and ground, sterilized in 10% bleach for 3 minutes, rinsed, and distributed into petri plates with selective media for each pathogen. FG was also evaluated by extracting DNA from 0.1g of soil and root samples and qPCR was conducted using species specific primers/probes. Presence of all 3 pathogens were observed in 7 samples which included all 4 counties. Correlations and analysis of variance among DNA and CFU of FG; soil CFU and root CFU of FG and MP; and other factors influencing disease development such as no-till practices, cultivar resistance, soil texture, will be conducted and presented.</div>