Sensitivity of Phakopsora pachyrhizi Isolates to Fungicides and Reduction of Fungal Infection Based on Fungicide and Timing of Application

Abstract

Soybean rust (SBR), caused by Phakopsora pachyrhizi, is a damaging foliar fungal disease in many soybean-growing areas of the world. Strategies to manage SBR include the use of foliar fungicides. Fungicide types, the rate of product application, and the number and timing of applications are critical components for successful rust management. The objectives of this study were to determine i) the sensitivity of P. pachyrhizi isolates collected in the U.S. to a range of fungicides and ii) the reduction of fungal infection based on fungicide type and timing of applications on soybean. There were differences (P < 0.05) in effective concentration (EC50) values among the fungicides tested. Azoxystrobin had low EC50 values for both urediniospore germination and fungal sporulation on inoculated leaflets. There were differences (P < 0.05) in fungal sporulation for application times, fungicide treatments, and their interaction when the fungus was inoculated on plants. All application times and nearly all fungicide treatments reduced (α = 0.05) fungal infection compared with the nonfungicide control. Information on fungicide sensitivity of P. pachyrhizi isolates and the preventive and curative effects of different fungicides are important in the management of SBR.

Untargeted Metabolomics Analysis by UHPLC-MS/MS of Soybean Plant in a Compatible Response to Phakopsora pachyrhizi Infection

“…Measures to control fungal growth are centered on the use of fungicides. However, there is a growing concern about the use of such fungicides due to environmental impact, human health, and the appearance of resistant P. pachyrhizi strains [6]. The constant use of triazole and strobilurin fungicides, for example, has resulted in the development of increased tolerance in P. pachyrhizi populations [7].…”

Potential of the Dithiocarbimate Fungicides on the Control of Coffee Leaf Rust and Asian Soybean Rust

“…The use of multi-site fungicides has become indispensable to reduce the selection pressure on the pathogen population. Several studies of multiple resistance to triazole, strobilurin, and dicarboxamide groups are reported in the literature (Schmitz et al, 2014;Twizeyimana & Hartman, 2017;Simões et al, 2018). Currently, the companies have been using multi-site fungicides developed in the 1950-60s (Zambolim & Caixeta, 2018;Reis et al, 2021).…”

Mapping and confirmation of two genes conferring resistance to soybean rust (Phakopsora pachyrhizi) in the soybean line UG‐5 (Glycine max)

“…Fungicide applications have been used to reduce yield losses caused by SBR (Allen et al, 2014; Murithi et al, 2016; Twizeyimana & Hartman, 2017). These increase production costs and the risk of fungicide resistance (Calvo et al, 2008; Price et al, 2015).…”

“…The F129L mutation results in reduced sensitivity to demethylation inhibitor (DMI) and quinone outside inhibitor (Qol) fungicides (Klosowski et al, 2016). Soybean cultivars with resistance to SBR would be a valuable component in an integrated disease management (Twizeyimana & Hartman, 2017).…”