In vitro sensitivity of Fusarium graminearum isolates to fungicides

Abstract

Head blight of wheat is a disease of global importance. In Brazil, it can cause damage of up to 27%. As resistant cultivars are not available yet, short-term disease control relies on the use of fungicides. The first step to reach effective management is to identify potent fungicides. In vitro experiments were conducted to determine the inhibitory concentration 50% (IC50) for mycelial growth or conidial germination, according to the chemical group of fungicides, of five Fusarium graminearum isolates of different origins. The following demethylation inhibitor (DMI) fungicides were tested: epoxiconazole, cyproconazole, metconazole, prochloraz, protioconazole and tebuconazole. In addition, azoxystrobin, kresoxim-methyl, pyraclostrobin and trifloxystrobin were included in the study, representing Quinone outside inhibitor fungicides (QoI), as well as a tubulin synthesis inhibitor, carbendazim and two ready mixtures, trifloxystrobin + tebuconazole or trifloxistrobin + prothioconazole. DMI's showed lower IC50 values compared to the QoI's. For the five tested isolates, in the overall mean, IC50 considering mycelial growth ranged for DMI's from 0.01 mg/L (metconazole, prochloraz and prothioconazole) to 0.12 mg/L (cyproconazole) and considering conidial germination for QoI's from 0.21 mg/L (azoxystrobin) to 1.33 mg/L (trifloxystrobin). The IC50 for carbendazim was 0.07 mg/L. All tested isolates can be considered sensitive to the studied DMI's, although certain differences in sensitivity could be detected between the isolates originating from one same state.

Sensitivity of Fusarium oxsporum Isolates Collected from Strawberry Rots to QoI Fungicides Azoxystrobin and Trifloxystrobin

“…RF (Resistance Factor) values for resistant isolates differed among the isolates and ranged between 2.87 to 101.84 (table 4). the current results agreed with previous studies of Avozani et al (2014a) who determined the inhibitory concentration of 50% (IC50) for conidial germination and the IC50 for azoxystrobin was 0.21mg/L. Song et al (2022) studied the baseline sensitivity of F. fujikuroi to azoxystrobin (AZO).…”

Assessment of the Sensitivity of Some Plant Pathogenic Fungi to 6-Demethylmevinolin, a Putative Natural Sensitizer Able to Help Overcoming the Fungicide Resistance of Plant Pathogens

“…Tebuconazole has been reported to show a good effect against a wide range of Fusarium species and other fungi during plant treatments, and its in vitro inhibitory effect has been well documented [33][34][35][36]. On the other hand, a widespread application of tebuconazole-containing formulations may promote selection and accumulation of tebuconazole-resistant strains in fungal populations [34,37,38] that decreases or even nullifies the sensitivity to tebuconazole resulting in in vitro variability of its fungicidal activity [39].…”

Antifungal and Phytotoxic Activities of Essential Oils: In Vitro Assays and Their Potential Use in Crop Protection

“…The antifungal activity of common synthetic antifungal agents has previously been reported. Among others, demethylation inhibitor (DMI), quinone outside inhibitor (QOI) fungicides [41], pimaricin [42] and tetraconazole [43] have been investigated for their fungicidal properties against Fusarium graminearum and Fusarium spp. The most efficient fungicide evaluated was pimaricin, with an IC50 ranging from 2.5 up to 5 µg L −1 , whereas the IC50 reported for tetraconazole was 16 µg L −1 and the ones obtained with DMI and QOI were 0.01 mg L −1 and 0.2 to 1.3 mg L −1 , respectively.…”