Effect of adding fungicide to mixtures of triazoles and strobilurins in the control of downy mildew and Asian soybean rust

Zuntini, Bruno; Alvarez, Rita de Cássia Félix; Theodoro, Gustavo de Faria; Zuffo, Alan Mário

doi:10.1590/1983-40632019v4953688

Cited by 9 publications

(8 citation statements)

References 18 publications

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“…Downy mildew is a disease with a very high potential for dissemination (Silva et al, 2011). Zuntini et al (2019), state that downy mildew occurs in practically all soybean producing regions in Brazil, mainly in the vegetative phase of soybeans, corroborating with the data from the present experiment, since the first symptoms of downy mildew, in the first harvest, occurred at the beginning of the vegetative stage V3 of the crop and the maximum severity (1.12%) occurred in the reproductive stage R1. After stage R1 in the fourth evaluation, the disease declined.…”

Section: Discussionsupporting

confidence: 90%

Alternative Products to Control Soybean Downy Mildew in the Field

Gabardo¹,

Pria²,

Silva³

et al. 2020

JAS

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Soybean mildew caused by Oomycota Peronospora manshurica, is a disease widely spread in Brazil. In order to study the efficiency of soybean mildew control due to the application of alternative products and fungicide in the field, experiments were conducted in Ponta Grossa, PR, Brazil, during the 2013/2014 and 2014/2015 growing seasons. The design used was randomized blocks with four replications. The treatments were: 1-witness; 2-acibenzolar-S-methyl; 3-calcium; 4-micronutrients: copper, manganese and zinc; 5-micronutrients: manganese, zinc and molybdenum; 6-NK fertilizer; 7-Ascophyllum nodosum and 8-azoxystrobin + cyproconazole with the addition of Nimbus adjuvant. Four applications of alternative products (phenological stages V3, V6, R1 and R5.1) and two of fungicide (phenological stages R1 and R5.1) were performed. The mildew severity was estimated using a diagrammatic scale. The severity data made it possible to calculate the area under the disease progress curve (AUDPC). In the 2014/2015 harvest the disease was more severe. The control of downy mildew by the use of fungicide did not reduce the epidemic. The fungicide was not efficient in the two evaluated seasons. All tested alternative products reduced the disease severity and AUDPC in both seasons. The best results in reducing downy mildew were found with the application of acibenzolar-S-methyl, micronutrients (Cu, Mn, Zn) and A. nodosum.

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Section: Discussionsupporting

confidence: 90%

Alternative Products to Control Soybean Downy Mildew in the Field

Gabardo¹,

Pria²,

Silva³

et al. 2020

JAS

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“…At the field level, warnings could include rainfall forecasts, which is also critical information for operational decision making as spray may be on hold if rain is very likely in the next day. This topic could be explored in future research, together with other factors which were not taken into account in our study such as differences in soybean maturity groups, host resistance, and more complex fungicide programs that involve different systemic fungicides combined with the use of multi-site and protectant fungicides, which have been used as an anti-resistance strategy (Godoy et al 2016;Zuntini et al 2019).…”

Section: Discussionmentioning

confidence: 99%

Performance and Profitability of Rain-Based Thresholds for Timing Fungicide Applications in Soybean Rust Control

et al. 2020

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Soybean rust (SBR), caused by the fungus Phakopsora pachyrhizi, is the most damaging disease of soybean in Brazil. Effective management is achieved by means of calendar-timed sprays of fungicide mixtures, which do not explicitly consider weather-associated disease risk. Two rain-based action thresholds of disease severity values (DSV50 and DSV80) were proposed and compared with two leaf wetness duration-temperature thresholds of daily values of infection probability (DVIP6 and DVIP9) and with a calendar program, with regard to performance and profitability. An unsprayed check treatment plot was included for calculating relative control. Disease severity and yield data were obtained from 29 experiments conducted at six sites across four states in Brazil during the 2012–13, 2014–15, and 2015–16 growing seasons, which represented different growing regions and climatic conditions. The less conservative rainfall action threshold (DSV80) resulted in fewer fungicide sprays compared with the other treatments, and the more conservative one (DSV50) resulted in fewer sprays than the DVIP thresholds. Yield was generally higher with the increase in spray number, but the economic analysis showed no significant differences in the risk of not offsetting the costs of fungicide sprays regardless of the system. Therefore, based on the simplicity and the profitability of the rain-based model, the system is a good candidate for incorporating into the management of SBR in soybean production fields in Brazil.

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“…Furthermore, a phytotoxic injury in the form of necrotic spots has been observed on leaves treated with this triazole-based fungicide. It has been reported that DMI fungicides including triazoles can cause phytotoxic damage on some soybean varieties, particularly under water stress or elevated temperatures [65,66]. However, Osiris ® with protective and curative activities is registered for controlling cereal rusts.…”

Section: Discussionmentioning

confidence: 99%

New Approaches to Manage Asian Soybean Rust (Phakopsora pachyrhizi) Using Trichoderma spp. or Their Antifungal Secondary Metabolites

et al. 2022

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Attempts have been made to determine the in vitro and in planta suppressive potential of particular Trichoderma strains (T16 and T23) and their secondary metabolites (SMs) against Asian soybean rust (ASR) incited by Phakopsora pachyrhizi. Aside from the previously identified SMs 6-pentyl-α-pyrone (6PAP) and viridiofungin A (VFA), the chemical structures of harzianic acid (HA), iso-harzianic acid (iso-HA), and harzianolide (HZL) were characterized in this study. Our results indicate that exposure of urediospores to 200 ppm 6PAP completely inhibits germination. A slightly higher dosage (250 ppm) of HZL and VFA reduces germination by 53.7% and 44%, respectively. Germ tube elongation seems more sensitive to 6PAP than urediospore germination. On detached leaves, application of conidia of T16 and T23 results in 81.4% and 74.3% protection, respectively. Likewise, 200 ppm 6PAP recorded the highest ASR suppression (98%), followed by HZL (78%) and HA (69%). Treatment of undetached leaves with 6PAP, HA, or HZL reduces ASR severity by 84.2%, 65.8%, and 50.4%, respectively. Disease reduction on the next, untreated trifoliate by T23 (53%), T16 (41%), HZL (42%), and 6PAP (32%) suggests a translocation or systemic activity of the SMs and their producers. To our knowledge, this study provides the first proof for controlling ASR using antifungal SMs of Trichoderma. Our findings strongly recommend the integration of these innovative metabolites, particularly 6PAP and/or their producers in ASR management strategies.

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Effect of adding fungicide to mixtures of triazoles and strobilurins in the control of downy mildew and Asian soybean rust

Cited by 9 publications

References 18 publications

Alternative Products to Control Soybean Downy Mildew in the Field

Alternative Products to Control Soybean Downy Mildew in the Field

Performance and Profitability of Rain-Based Thresholds for Timing Fungicide Applications in Soybean Rust Control

New Approaches to Manage Asian Soybean Rust (Phakopsora pachyrhizi) Using Trichoderma spp. or Their Antifungal Secondary Metabolites

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