SUMMARYGrowth 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 (EC 50 ) 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. EC 50 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. EC 50 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. EC 50 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 EC 50 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.

Symptoms of bitter rot were observed on apple and pear fruits in the field and in storage in Croatia between 2009 and 2011. Fifteen Colletotrichum isolates from apple and two from pear were collected and identified by sequencing of the ITS1 and ITS2 regions of the ribosomal DNA. Phylogenetic analysis revealed that ten isolates from apple and two isolates from pear could be identified as Colletotrichum fioriniae, five isolates from apple were clustered in Colletotrichum clavatum, while one isolate was in the Colletotrichum acutatum A7 group. All isolates caused typical bitter rot symptoms when inoculated on apple and pear fruits.

Several species of the genus Fusarium can cause apple fruit to rot while stored. Since Fusarium taxonomy is very complex and has constantly been revised and updated over the last years, the aim of this study was to identify Fusarium species from rotten apples, based on combined morphological characteristics and molecular data. We identifi ed 32 Fusarium isolates from rotten apple fruit of cultivars Golden Delicious, Jonagold, Idared, and Pink Lady, stored in Ultra Low Oxygen (ULO) conditions. Fusarium rot was detected in 9.4 % to 33.2 % of naturally infected apples, depending on the cultivar. The symptoms were similar in all four cultivars: a soft circular brown necrosis of different extent, with or without visible sporulation. Fusarium species were identifi ed by the morphology of cultures grown on potato-dextrose agar (PDA) and carnation leaf agar (CLA). Twenty one isolates were identifi ed as Fusarium avenaceum and confi rmed as such with polymerase chain reaction (PCR) using specifi c primer pair FA-ITSF and FA-ITSR. F. pseudograminearum, F. semitectum, F. crookwellense, and F. compactum were identifi ed by morphological characteristics. F. avenaceum can produce several mycotoxins and its dominance in Fusarium rot points to the risk of mycotoxin contamination of apple fruit juices and other products for human consumption. Pathogenicity tests showed typical symptoms of Fusarium rot in most of the inoculated wounded apple fruits. In this respect Fusarium avenaceum, as the dominant cause of Fusarium rot in stored apple fruits is a typical wound parasite.

No abstract

No abstract