Effect of fungicides on the complex of Fusarium species and saprophytic fungi colonizing wheat kernels

Abstract

Fusarium head blight of wheat, often associated with mycotoxin contamination of food and feed is caused by various Fusarium species. The efficacy of fungicide sprays for the control of the disease and mycotoxins varies from being highly effective to even increasing mycotoxin levels. The potential role of antagonistic fungi in this variability was investigated assessing sensitivity of Fusarium species and saprophytic fungi colonizing wheat kernels to fungicides. Saprophytes were tested for their antagonistic activity to the prevalent Fusarium species Fusarium avenaceum, Fusarium culmorum, Fusarium graminearum, and Fusarium poae. Fungal isolates from mature winter wheat kernels were Alternaria alternata, Arthrinium sp., Aspergillus niger, Epicoccum sp., Microdochium spp., Rhizopus oryzae and Trichoderma sp. In dual culture A. niger, R. oryzae and Trichoderma hamatum were more effective in reducing mycelial growth of Fusarium species than Microdochium majus; A. alternata and Epicoccum sp. were ineffective because of slow growth rates. Saprophytic fungi were sensitive to triazoles; however, prothioconazole and tebuconazole had stronger effects on mycelial growth of Fusarium species. ED 50 values also indicated significant differences in the sensitivity of Fusarium species to triazoles (range 0.1-1.7 mg l −1 ). Azoxystrobin and fluoxastrobin were largely ineffective in inhibiting in vitro growth of Fusarium spp.; sensitivity of the other fungi was generally lower, except for M. majus which was highly sensitive. Due to differences in fungicide sensitivity among Fusarium spp. and ear-colonizing fungi antagonistic to Fusarium spp. fungicides are likely to modify the balance within the mycoflora of wheat ears which may also affect the mycotoxin contamination of grain.

In vitro sensitivity of Fusarium graminearum, F. avenaceum and F. verticillioides to carbendazim, tebuconazole, flutriafol, metconazole and prochloraz

“…In this study, the mean growth inhibition of F. graminearum isolates on 1 mg l -1 of tebuconazole was 50%, while it was 83% on the same concentration of carbendazim. However, the results of this study determined for fungicide tebuconazole were relatively similar to results of Müllenborn et al (2008). In a similar experiment, ED 50 values recorded for different Fusarium isolates on tebuconazole were from 0.24 mg l -1 to 6.5 mg l -1 (Müllenborn et al, 2008).…”

Efficacy of Biological Control and Cultivar Resistance on <i>Fusarium</i> Head Blight and T-2 Toxin Contamination in Wheat

“…However, under field conditions, fungicides have low efficacy levels and hence the efforts to seek alternative FHB management strategies. Under greenhouse conditions, none of the fungicides completely controlled the FHB pathogens but only suppressed them concurring with earlier findings [31][32][33].…”

Study of metabolite profiles in winter wheat cultivars induced by Fusarium infection

“…It is very difficult to refer to this fact in view of the results collected so far. The observed differences between contents of fungal metabolites and phenolic acids between the population of K and OCH samples may be explained by the fact that sublethal concentrations of fungicides trigger trichothecene biosynthesis (Ochiai et al 2007;Müllenborn et al 2008). On the other hand, all fungicides (prothioconazole, tebuconazole, metconazole and prothioconazole + tebuconazole) used in the study reduced FHB index and deoxynivalenol (DON) levels according to Amarasinghe et al (2013).…”