Biological and Chemical Management of Aspergillus carbonarius and Ochratoxin A in Vineyards

Abstract

Ochratoxin A (OTA) is a widely distributed mycotoxin and potent carcinogen produced by several fungal genera, but mainly by Aspergillus carbonarius. Grape contamination occurs in vineyards during the period between veraison and pre-harvest, and it is the main cause of OTA's presence in wine. The aim of the current study was the evaluation of 6 chemical and 11 biological plant protection products (PPPs) and biocontrol agents in commercial vineyards of the two important Greek white wine varieties cv. Malagousia and cv. Savatiano. The PPPs were applied in a 4-year vineyard study as single treatments or/and in combinations as part of IPM systems. Subsequently, nine strains of Aspergillus carbonarius were investigated for their sensitivity against seven active compounds of synthetic fungicides. During the multi-year field trials, various novel management systems, including consortia of biocontrol agents, were revealed to be effective against Aspergillus sour rot and OTA production. However, expected variability was observed in the experimental results, indicating the dynamic character of biological systems and highlighting the possible inconsistency of PPPs' efficacy in a changing environment. Furthermore, the IPM systems developed effectuated an optimized control of A. carbonarius, leading to 100% inhibition of OTA contamination, showing the importance of using both chemical and biological PPPs for disease management and prevention of fungal fungicide resistance. Finally, the majority of A. carbonarius tested strains were found to be sensitive against the pure active compounds used (fludioxonil, azoxystrobin, chlorothalonil, tebuconazole, cyprodinil, pyrimethanil and boscalid), with only a few exceptions of developed resistance towards boscalid.

Keywords: Aspergillus carbonarius; IPM; biopesticides; biostimulants; fungicides; grapes; ochratoxin-A; vineyards.

Figure 1

Disease severity of Aspergillus sour rot in grape berries of cv. Malagousia variety after PPP treatment of vines in the years 2016–2019. Statistical analysis was performed using one-way ANOVA followed by Tukey’s multiple-comparison post hoc test (p < 0.05). Letters above the graphs indicate differences between treatments.

Figure 2

Disease severity of Aspergillus sour rot in grape berries of cv. Savatiano variety after PPP treatment of vines in the years 2016–2019. Statistical analysis was performed using one-way ANOVA followed by Tukey’s multiple-comparison post hoc test (p < 0.05). Letters above the graphs indicate differences between treatments.

Figure 3

Ochratoxin A levels (μg kg⁻¹) produced by Aspergillus carbonarius in cv. Malagousia after PPP treatment of vines in the years 2016–2019. Statistical analysis was performed using one-way ANOVA followed by Tukey’s multiple-comparison post hoc test (p < 0.05). Letters above the graphs indicate differences between treatments.

Figure 4

Ochratoxin A levels (μg kg⁻¹) produced by Aspergillus carbonarius in cv. Savatiano after PPP treatment of vines in the years 2016–2019. Statistical analysis was performed using one-way ANOVA followed by Tukey’s multiple-comparison post hoc test (p < 0.05). Letters above the graphs indicate differences between treatments.