In vitro sensitivity reduction of Fusarium graminearum to DMI and QoI fungicides

Abstract

Wheat (Triticum aestivum L.) is an important food crop in Brazil, where the annual consumption is currently around 11 million tons, of which 6 million tons are produced and 5.6 million tons are imported (5). Wheat production under prevailing warm and wet weather conditions, as in Southern Brazil, is a difficult task (15).Fungal diseases cause considerable damage to wheat production, particularly those difficult to control, such as fusarium head blight (FHB), caused by Gibberella zeae (Schw.) Petch. (Anamorph Fusarium graminearum Schw.). FHB was first described in the United States, in 1891 (19), and in Brazil, in Veranópolis County, Rio Grande do Sul, in 1942, by Costa Netto (7). RESUMOPalavras-chave adicionais: Giberela, fungitoxicidade, CI 50 , Triticum aestivum, trigo.Os danos causados pela giberela em trigo, no Brasil, podem chegara a 39,8%. Ainda não estão disponíveis cultivares resistentes para o controle da doença; desse modo, à curto prazo, o controle da doenças é baseado no uso de fungicidas. O primeiro passo para melhorar a eficácia do controle é monitorar a sensibilidade do fungo aos fungicidas para obter o manejo mais eficiente da doença. Experimentos foram conduzidos in vivo para avaliar a concentração inibitória (CI 50 ) de fungicidas tanto para o crescimento miceliano como para a germinação de conídios de dez isolados de Fusarium graminearum. Os seguintes fungicidas inibidores da desmetilação (IDM) foram testados: metconazol, protioconazol e tebuconazol. Também, foram testados os fungicidas inibidores da quinona externa (IQe) estrobilurinas, piraclostrobina e trifloxistrobina, bem Avozani, A.; Reis, E. M.; Tonin R. B. Redução in vivo da sensibilidade de Fusarium graminearum a fungicidas triazóis e estrobilurinas. Summa Phytopathologica, v.40, n.4, p.358-364, 2014. como suas misturas contendo metconazol + piraclostrobina, protioconazol + trifloxistrobina, e tebuconazol + trifloxistrobina. A média geral da CI 50 para o crescimento miceliano dos isolates foi: metconazol 0,07, protioconazol 0,1, e tebuconazol 0,19 mg/L. Para as misturas foi: protioconazol + trifloxistrobina 0,08, tebuconazol + trifloxistrobina 0,12, e metconazol + piraclostrobin 0,14 mg/L. Em relação a inibição da germinação dos esporos, a CI 50 para protioconazol + trifloxistrobina foi 0,06, para o tebuconazol + trifloxistrobina, 0,12 mg/L, e para os IQes isolados piraclostrobina, 0,09, e para a for trifloxistrobina, 0,28 mg/L. Demonstrou-se haver um diferença na sensibilidade entre os isolados e confirmou-se a elevada fungitoxicidade do protioconazol, metconazol e tebuconazol à F. graminearum. In Brazil, Fusarium head blight (FHB) affecting wheat can cause up to 39.8% damage. Resistant cultivars are not available yet; thus, short-term disease control relies on the use of fungicides. The first step to improve control is to monitor fungal populations that are sensitivity to chemicals in order to achieve efficient FHB management. In vitro experiments were conducted to evaluate the inhibitory concentration (IC 50 ) of fungi...

Phenotypic and molecular characterization of the resistance to azoxystrobin and pyraclostrobin in Fusarium graminearum populations from Brazil

“…A similar result was found when pyraclostrobin was compared to azoxystrobin against Cercospora spp. isolates, and even when pyraclostrobin was compared to trifloxystrobin against F. graminearum isolates (Avozani et al, 2014;de Mello et al, 2021). For the latter, a recent meta-analysis conducted in Brazil, which compared several DMI + QoI premixes for FHB control, showed that a premix containing azoxystrobin was less effective than one that used pyraclostrobin.…”

“…graminearum to this chemical group. To date, only one study has been conducted in the country, which used 10 FGSC strains from Rio Grande do Sul (RS) and Paraná (PR) states to characterize their EC 50 (effective concentration leading to 50% inhibition of conidial germination; Avozani et al, 2014). The objectives of this study were (a) to characterize the sensitivity of F .…”

“…This explains why the 143 mutation was not found in any rusts and Alternaria solani (Grasso et al, 2006). Information about the resistance in F. graminearum strains to QoI fungicides is scarce and controversial (Audenaert et al, 2010;Avozani et al, 2014;Duan et al, 2020). Audenaert et al (2010) showed that azoxystrobin did not affect the conidial germination of a wild-type strain.…”

“…Due to the importance of chemical control for managing FHB in Brazil, which includes the use of QoI fungicides in commercial premixes (Barro et al, 2021), it is urgent to characterize the sensitivity of F. graminearum to this chemical group. To date, only one study has been conducted in the country, which used 10 FGSC strains from Rio Grande do Sul (RS) and Paraná (PR) states to characterize their EC 50 (effective concentration leading to 50% inhibition of conidial germination; Avozani et al, 2014). The objectives of this study were (a) to characterize the sensitivity of F. graminearum that causes FHB of wheat in Brazil to two most used QoI fungicides (azoxystrobin and pyraclostrobin), and (b) to detect the presence of known point mutations associated with resistance to these fungicides.…”

Polymerase Chain Reaction-Assisted Evaluation of the Efficacy of Seed-Treatment Prevention of Sporisorium reilianum Infection in Sorghum Seedlings

“…piricola, respectively (Jian-lu et al, 2007). The mean EC 50 of tebuconazole, based on the inhibition of mycelial growth of 10 Fusarium graminearum isolates, was reported to be 0.19 mg/L (Avozani et al, 2014). The EC 50 and EC 90 values for 43% tebuconazole suspension concentrates against Phomopsis asparagi is 7.4241 and 47.1322 mg/L, respectively (Jia et al, 2009).…”