Integration between genetic and chemical control on the progress of Asian soybean rust and yield

Abstract

The objective of this study was to evaluate the genetic control integrated to the chemical control of Asian soybean rust (ASR) and the effects of these measures on crop yield. The experiment was conducted in Erechim, Rio Grande do Sul State, Brazil, in 2016/17 and 2017/18 crop years, under a randomized block design, in a subdivided plot scheme (cultivars in the plots and fungicides in the subplots), with four replicates. The following cultivars were used: BMX Vanguarda (without ASR tolerance); TMG 7062; TMG 7262, and TMG 7161, tolerant to ASR (Inox™ Technology cultivars). The fungicides used were: T1) control (without application of fungicides); T2) azoxystrobin + benzovindiflupyr; T3) difenoconazole + cyproconazole; T4) trifloxystrobin + prothioconazole, and T5) epoxiconazole + fluxapyroxad + pyraclostrobin. Four fungicide applications were carried out at the V6, R1, R5.1 and R6 stages. During the experiment, for the calculation of the area under disease progress curve (AUDPC), disease severity was assessed at 7-day intervals in a random sample of 10 trifolia per plot. After harvest, yield components were determined: number of grains per plant, thousand grain weight (g), and yield (kg ha-1). In 2017/18 crop year, the fungicide difenoconazole + cyproconazole was not efficient for ASR control. The soybean cultivars TMG 7062, TMG 7161 and TMG 7261 delayed the disease progression; however, only TMG 7161 presented tolerance in the presence of the inoculum in 2016/17 and 2017/18 crop years. The association between chemical and genetic control is shown to be efficient for ASR control.

Temporal and regional performance of dual and triple premixes for soybean rust management in Brazil: A meta-analysis update

“…The higher efficacy of the triple mixture (TFLX + PROT + BIXF) could not only be attributed to the addition of BIXF, since the amount of TFLX and PROT a.i./ha (75 + 87.5) in the triple mixture is superior than in the dual mixture (TFLX 60 + PROT 70). A recent two-year study, not included in our analysis, and conducted in the north of RS state (Sacon et al 2020) reported a 71% efficacy for TFLX + PROT, which was close to our overall estimates (72%), but both were numerically lower than the previous meta-analysis (83.6%) (Dalla Lana et al 2018) . Additionally, the authors found similar SBR control efficacy for PYRA + EPOX + FLUX (>70%) compared to the estimates reported here (72%).…”

“…However, the sole use of resistant cultivars as management choice has the same limitations of the fungicide use, which is the selection of pathogen populations capable of overcoming the Rpp genes ( Godoy et al 2016a ). Therefore, recent studies have investigated the interaction effect of chemical and genetic control (Bahry et al 2020;Sacon et al 2020 (Godoy et al 2016c(Godoy et al , 2017b(Godoy et al , 2018b and more data becoming available in the near future should be amenable for meta-analysis, and so quantitatively estimate the benefits of multi-site fungicides.…”

Performance of dual and triple fungicide premixes for managing soybean rust across years and regions in Brazil: A meta‐analysis

“…A two‐year study (2016/17 to 2017/18) conducted in Paraná state found a significant reduction in SBR severity when combining fungicide treatment (AZOX + BENZ) with a resistant cultivar (TMG 7062; c.72%); slightly less reduction was obtained when fungicide was combined with the highly tolerant cultivar LG 60163 (c.64%) and less still with the susceptible cultivar NA 5909 (c.52.1%) (Bahry et al, 2020). Sacon et al (2020) also reported higher SBR control applying AZOX + BENZ to resistant cultivars (>80%) compared to a susceptible one (c.56%) in field experiments conducted in northern Rio Grande do Sul state during 2016/17 and 2017/18 growing seasons.…”

“…The higher efficacy of the triple mixture (TFLX + PROT + BIXF) could not be attributed only to the addition of BIXF, because the amount of TFLX and PROT a.i./ha (75 + 87.5) in the triple mixture is higher than in the dual mixture (TFLX 60 + PROT 70). A recent two-year study, not included in our analysis, conducted in the north of RS state (Sacon et al, 2020), reported a 71% efficacy for TFLX + PROT, which was close to our overall estimates (72% efficacy), but both were numerically lower than in the previous meta-analysis (83.6% efficacy;Dalla Lana et al, 2018). Additionally, the authors reported SBR control efficacy for PYRA + EPOX + FLUX (>70%) (Sacon et al, 2020) similar to the estimates reported here (72%).…”

“…A recent two-year study, not included in our analysis, conducted in the north of RS state (Sacon et al, 2020), reported a 71% efficacy for TFLX + PROT, which was close to our overall estimates (72% efficacy), but both were numerically lower than in the previous meta-analysis (83.6% efficacy;Dalla Lana et al, 2018). Additionally, the authors reported SBR control efficacy for PYRA + EPOX + FLUX (>70%) (Sacon et al, 2020) similar to the estimates reported here (72%).…”