Are Demethylation Inhibitor Plus Quinone Outside Inhibitor Fungicide Premixes During Flowering Worthwhile for Fusarium Head Blight Control in Wheat? A Meta-Analysis

Abstract

Fusarium head blight (FHB), caused mainly by Fusarium graminearum, is best controlled with demethylation inhibitor (DMI) fungicides during flowering. However, the use of premixes of DMI and quinone outside inhibitor (QoI) fungicides to control FHB has increased in Brazil. Data on FHB severity and wheat yields measured in field experiments conducted in Brazil were gathered from both peer- and non-peer-reviewed sources published from 2000 to 2018. After applying selection criteria, 73 field trials from 35 bibliographic sources were identified, among which 50% of the data were obtained from cooperative network trials conducted after 2011. To be included in the analysis, a DMI+QoI premixes or tebuconazole (TEB) were tested in at least 14 trials and three years. Four premixes met the criteria. Estimates of percent control (and respective 95% confidence interval) by a network model fitted to the log of the treatment means ranged from 44.1% (pyraclostrobin + metconazole applied once; 32.4 to 53.7) to 64.3% (pyraclostrobin + metconazole; 58.4 to 69.3); the latter not differing from TEB (59.9%, 53.6 to 65.3). Yield response was statistically similar for pyraclostrobin + metconazole (532.1 kg/ha, 441 to 623) and trifloxystrobin + prothioconazole (494.9 kg/ha, 385 to 551), and both differed statistically from a group composed of TEB (448.2 kg/ha, 342 to 554), trifloxystrobin + TEB (468.2 kg/ha, 385 to 551), azoxystrobin + TEB (462.4 kg/ha, 366 to 558) and pyraclostrobin + metconazole applied once (413.7 kg/ha, 308 to 518). The two categories of FHB index (7% cut off) and yield (3,000 kg/ha cut off), both in the non-treated check, did not explain the heterogeneity in the estimates. Two sequential sprays of TEB or one spray of pyraclostrobin + metconazole as management choices are likely more profitable than DIM+QoI premixes sprayed twice during flowering considering only the fungicide effects on yield.

Sequential post-heading applications for controlling wheat blast: a summary of fungicide performance

“…Tebuconazole is an affordable option widely used by Brazilian growers not only for controlling wheat blast, but also for managing other important wheat diseases such as Fusarium head blight (Machado et al 2017;Duffeck et al 2020;Barro et al 2020). The mean estimates of TEBU applied solo (54%) as well as the premix TFLX + TEBU (52%) reported in our metaanalysis were very similar to a two-year study (TEBU = 57%; TFLX + TEBU = 50%) conducted in Midwest Brazil during 2010 and 2011 crop seasons (Pagani et al 2014).…”

“…Meta-analytic approaches have become standard to summarize the effect of treatments for fungicide testing data, including wheat diseases (Paul et al 2008(Paul et al , 2018aMachado et al 2017;Barro et al 2019Barro et al , 2020. Uniform fungicide trials targeting wheat blast control were established in 2011 and performed yearly following a standardized protocol.…”

Phenotypic and molecular characterization of the resistance to azoxystrobin and pyraclostrobin inFusarium graminearumpopulations from Brazil

“…This appears controversial in view of reports that showed that strobilurin fungicides can stimulate DON production by up‐regulating the expression of Tri5 and Tri6 genes and increasing acetyl‐CoA production (Duan et al, 2020). However, technical and economic benefits from the use of premixes, especially when mixed with DMIs, have been reported in the region (Barro et al, 2021; Feksa et al, 2019; Paul et al, 2018).…”

“…there are no commercial wheat cultivars in Brazil with adequate levels of resistance to control FHB without the need for fungicides (Barro et al, 2021). Therefore, farmers rely on fungicides such as demethylation inhibitors (DMI), a class of triazole compounds.…”

Linking Multi-Omics to Wheat Resistance Types to Fusarium Head Blight to Reveal the Underlying Mechanisms

“…However, most of them showed minor effects and their expressions were greatly affected by the environment, genetic background, and inoculation method. Meta-QTL (MQTL) analysis of these QTL could shrink their confidence intervals and identify the QTL regions most commonly associated with trait variation [78][79][80]. A recent report conducted a meta-analysis of QTL for Type II and III resistances over the past 20 years, showing that a total of 529 QTL were for Type II resistance.…”