Baseline Sensitivity of Fusarium virguliforme to Fluopyram Fungicide

Abstract

Fluopyram, a succinate dehydrogenase inhibitor (SDHI) fungicide, was recently registered for use as a soybean seed treatment for management of sudden death syndrome (SDS) caused by Fusarium virguliforme. Although registered and now used commercially, in vitro baseline fungicide sensitivity of F. virguliforme to fluopyram has not yet been established. In this study, the baseline sensitivity of F. virguliforme to fluopyram was determined using in vitro growth of mycelium and germination of conidia assays with two collections of F. virguliforme isolates. A total of 130 and 75 F. virguliforme isolates were tested using the mycelial growth and conidia germination assays, respectively, including a core set of isolates that were tested with both assays. In the mycelial growth inhibition assay, 113 out of 130 isolates (86.9%) were inhibited 50% by effective concentrations (EC50) less than 5 µg/ml with a mean EC50 of 3.35 µg/ml. For the conidia germination assay, 73 out of 75 isolates (97%) were determined to have an estimated EC50 of less than 5 µg/ml with a mean EC50 value of 2.28 µg/ml. In a subset of 20 common isolates that were phenotyped with both assays, conidia germination of F. virguliforme was determined to be more sensitive to fluopyram (mean EC50 = 2.28 µg/ml) than mycelial growth (mean EC50 = 3.35 µg/ml). Hormetic effects were observed in the mycelial growth inhibition assay as 22% of the isolates demonstrated more growth on medium amended with the lowest fluopyram concentration (1 µg/ml), as compared with the nonfluopyram amended control. It was not possible to determine EC50 values for nine out of 185 isolates (4.8%), as those isolates were not inhibited by 50% even at the highest fluopyram concentrations of 100 µg/ml for mycelial growth and 20 µg/ml for conidia germination inhibition assays. On the whole, the F. virguliforme population appears to be sensitive to fluopyram, and this study enables future monitoring of fungicide sensitivity.

Fluopyram Sensitivity and Functional Characterization of SdhB in the Fusarium solani Species Complex Causing Soybean Sudden Death Syndrome

“…In 2014, the succinate dehydrogenase inhibitor (SDHI), fluopyram, was registered as a seed treatment (ILeVO, Bayer Crop Science) and has been widely used in soybean fields because of its effective suppression of SDS ( Kandel et al, 2016 , 2018 ). Wang et al (2017) established baseline sensitivity of F. virguliforme isolates from different states to fluopyram. The majority of F. virguliforme isolates characterized in the study displayed sensitivity to fluopyram (mean EC 50 = 3.35 μg ml -1 ) ( Wang et al, 2017 ).…”

“… Wang et al (2017) established baseline sensitivity of F. virguliforme isolates from different states to fluopyram. The majority of F. virguliforme isolates characterized in the study displayed sensitivity to fluopyram (mean EC 50 = 3.35 μg ml -1 ) ( Wang et al, 2017 ). Although this information is useful in efforts to prolong the product life of fluopyram to F. virguliforme , the sensitivity of other important SDS pathogens like F. brasiliense and F. tucumaniae to fluopyram has not been determined.…”

Naive Forecast for COVID-19 in Utah Based on the South Korea and Italy Models-the Fluctuation between Two Extremes

“…We first start with reported data (i.e., the cumulative daily sum of new cases from March 4th through April 4th in Utah, as reported by Utah Department of Health), and then end with the predicted data based on step-II (i.e., the continued cumulative daily sum of new cases from 5 April through 28 April based on the South Korea model and 24 April based on the Italy model. (4) The fourth step of the forecast is to fit a log-logistic model with four-parameters [9][10][11] for the cumulative number of cases, generated in step-3. This helps calculate the expected time for the peak of the pandemic (i.e., the incidence turning point) and expected time for the full carrying capacity of the outbreak (i.e., the total number of cumulative cases encountered throughout the pandemic).…”

Integrated management of Mi-1 virulent Meloidogyne incognita (Kofoid & White, 1919) Chitwood, 1949 (Tylenchida: Meloidogynidae) in greenhouse tomatoes

“…As mentioned above, fluopyram is an SDHI fungicide that is being evaluated for management of soilborne fungi and plant-parasitic nematodes in agronomic crops. The effect of fluopyramy on various fungi has been assessed, including its ability to control Neocosmospora virguliformis (O'Donnell & T. Aoki) L. Lombard & Crous, 2015 (Hypocreales: Nectriaceae) and many isolates of F. virguliforme showed sensitivity to fluopyram (Wang et al, 2017). Recently, a formulation that consists of fluopyram + imidacloprid has been considered as an in-furrow treatment for suppression of M. incognita and R. reniformis in cotton.…”