Fumonisin B1 and zearalenone contamination of wheat in Croatia and influence of fungicide treatments

In Croatia, a trial was conducted to determine the presence of the Fusarium mycotoxins fumonisin B1 and zearalenone in wheat kernels and to evaluate the efficacy of nine fungicides on Fusarium head blight severity as well as fumonisin B1 and zearalenone accumulation in wheat grain. Fumonisin B1 and zearalenone were detected in all grain samples in mean concentrations ranging from 182.0 to 446.6 µg kg-1 (fumonisin B1) and from 2.59 to 5.33 µg kg-1 (zearalenone). No significant differences were found among fumonisin B1 and zearalenone content in wheat grain for the different fungicide treatments. No correlation was revealed between Fusarium head blight severity and fumonisin B1 or zearalenone content in wheat grain, nor between fungicide efficacy and fumonisin B1 or zearalenone content in wheat grain. Under conditions of high disease pressure, efficacy of the fungicides was between 85.7% (tebuconazole + triadimefon) and 72.1% (carbendazim).Un essai a été effectué en Croatie afin de déterminer la présence de fumonisine B1 et de zéaralenone, des mycotoxines de Fusarium, dans des grains de blé et d'évaluer l'efficacité de neuf fongicides à réduire la gravité de la brûlure de l’épi causée par le fusarium ainsi que l’accumulation de fumonisine B1 et de zéaralenone dans les grains de blé. La fumonisine B1 et la zéaralenone ont été détectées dans tous les échantillons de grains, avec des concentrations moyennes variant entre 182,0 et 446,6 µg kg-1 (fumonisine B1) et entre 2,59 et 5,33 µg kg-1 (zéaralenone). Aucune différence significative n’a été trouvée entre les différents traitements fongicides quant à la teneur en fumonisine B1 et en zéaralenone dans les grains de blé. Aucune corrélation positive n’a été obtenue entre la gravité de la brûlure de l’épi causée par le fusarium et la teneur en fumonisine B1 ou en zéaralenone dans les grains de blé, ou encore entre l’efficacité des fongicides et la teneur en fumonisine B1 ou en zéaralenone dans les grains de blé. Sous des conditions sévères de maladie, l’efficacité des fongicides se situait entre 85,7 % (tébuconazole + triadiméfon) et 72,1 % (carbendazime)

In vitro osetljivost vrsta Fusarium graminearum, F. avenaceum i F. verticillioides na karbendazim, tebukonazol, flutriafol, metkonazol i prohloraz

Growth of 13 F. graminearum isolates, 6 F. avenaceum isolates and 6 F. verticillioides isolates was analysed on potato-dextrose agar amended with 0.1, 0.33, 1, 3.3 and 10 mg l-1 of carbendazim, tebuconazole, flutriafol, metconazole, and prochloraz. Average concentration which reduced mycelial growth by 50% comparing it to control (EC50) was calculated for each isolate. Among fungicides tested, prochloraz was shown to be the most effective in growth inhibition of all three species, while flutirafol was proven to be the least effective. Metocnazole was more efficient in comparison with carbendazim and tebuconazole. EC50 values of all isolates on prochloraz were lower than 0.1 mg l-1, while on flutirafol they ranged between 1.66 and 8.51 mg l-1 for 18 isolates, or were higher than 10 mg l-1 for 7 isolates. EC50 values on carbendazim were 0.39-1.41 mg l-1 for F. graminearum isolates, 0.91-1.35 mg l-1 for F. avenaceum, and 0.47-0.6 mg l-1 for F. verticillioides. EC50 values on tebuconazole were 0.85- 2.57 mg l-1 for F. graminearum, 0.85-1.58 mg l-1 for F. avenaceum and 0.22-0.85 mg l-1 for F. verticillioides, while on metconazole EC50 values ranged between less than 0.1 mg l-1 to 1.66, 0.56, and 0.17 mg l-1 for F. graminearum, F. avenaceum and F. verticillioides, respectively. Average growth inhibitions of different Fusarium species and all Fusarium isolates together on different concentrations of fungicides tested were significantly different. Significant differences in growth were not determined among isolates of the same species on neither one of fungicides tested, indicating that no decreased sensitivity to the fungicides exists among isolates included in the study.U istraživanju je ispitan rast 13 izolata Fusarium graminearum, 6 izolata F. avenaceum i 6 izolata F. verticillioides na krompir-dekstroznoj podlozi s dodatkom 0,1, 0,33, 1, 3,3 i 10 mg/l karbendazima, tebukonazola, flutriafola, metkonazola i prohloraza. Za svaki izolat izračunata je srednja efektivna koncentracija (EC50), pri kojoj je prosečni rast izolata bio inhibiran za 50% u odnosu na kontrolu. Prohloraz je bio najučinkovitiji u inhibiciji rasta sve tri vrste, dok je flutirafol pokazao najmanju učinkovitost. Metkonazol je pokazao višu učinkovitost u poređenju s karbendazimom i tebukonazolom. EC50 vrednosti svih izolata na prohlorazu bile su manje od 0,1 mg/l, dok su na flutriafolu varirale između 1,66 i 8,51 mg/l za 18 izolata, ili bile veće od 10 mg/l za sedam izolata. EC50 vrednosti na karbendazimu bile su 0,39-1,41 mg/l za izolate F. graminearum, 0,91-1,35 mg/l za F. avenaceum, te 0,47-0,6 mg/l za F. verticillioides. Na tebukonazolu EC50 vrednosti bile su 0,85-2,57 mg/l za F. graminearum, 0,85-1,58 mg/l za F. avenaceum i 0,22-0,85 mg/l za F. verticillioides, dok su na metokonazolu utvrđene EC50 vrednosti između manjih od 0,1 do 1,66, 0,56 i 0,17 mg/l za F. graminearum, F. avenaceum i F. verticillioides. Prosečne inhibicije rasta različitih Fusarium vrsta i svih Fusarium izolata ukupno na različitim koncentracijama različitih fungicida značajno su se razlikovale. Nisu utvrđene značajne razlike u rastu između izolata unutar pojedinih Fusarium vrsta na niti jednom od ispitanih fungicida, što pokazuje da ne postoji smanjena osetljivost na fungicide kod izolata uključenih u istraživanje

Shoot necrosis caused by Phoma incompta, a new disease of olive in Croatia

Reddish-brown lesions on young shoots, withering of leaves, cankers on older shoots and shoot necrosis were observed on some olive trees in southern Croatia. The fungus Phoma incompta was identifed as the causal agent of the disease. Pathogenicity of P. incompta isolates was confrmed by inoculating young olive plants in a greenhouse; these plants developed symptoms similar to those observed in the field