BACKGROUND: Botryotinia fuckeliana (Botrytis cinerea) is a pathogen with a high risk of development of resistance to fungicides. Fungicide resistance was monitored during 2008-2011 in B. fuckeliana populations from both table-grape vineyards and greenhouse-grown strawberries in southern Italy. RESULTS:Isolates showing different levels of resistance to anilinopyrimidines (APs) were detected at high frequency (up to 98%) in fields treated intensively with APs (4-7 sprays season −1 ). A slight decrease in sensitivity to fludioxonil, always combined with AP resistance, was generally found at lower frequencies. The repeated use of fenhexamid on grapevine (3-8 sprays season −1 ) led to a strong selection of highly resistant isolates (up to 100%). Boscalid-resistant mutants were detected at very variable frequencies (0-73%). Occurrence of resistance to quinone outside inhibitors (QoIs) was also ascertained. Multiple fungicide resistance to 2-6 different modes of action were frequently recovered. Single nucleotide polymorphisms (SNPs) in the target genes Erg27, SdhB and cytb were associated with resistance to fenehexamid, boscalid and QoIs respectively. CONCLUSION: Resistance to the fungicides commonly used against grey mould on table grape and strawberry is quite common in southern Italy. This is an outcome of the incorrect use of fungicides, often because of the maximum number of detectable residues of plant protection products imposed by big international retailers, and underlines the crucial role of antiresistance strategies in integrated pest management.

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Fluopyram-resistant mutants are currently rarely detected in the field sprayed with boscalid, but this may change with intensive exposure of the fungal population to fluopyram. PCR assays/methods developed in the study provide tools for fast monitoring of field populations and observing possible changes in population composition following fluopyram introduction, useful for the setting-up of appropriate preventive measures.

Wheat, the main source of carbohydrates worldwide, can be attacked by a wide number of phytopathogenic fungi, included Alternaria species. Alternaria species commonly occur on wheat worldwide and produce several mycotoxins such as tenuazonic acid (TA), alternariol (AOH), alternariol-monomethyl ether (AME), and altenuene (ALT), provided of haemato-toxic, genotoxic, and mutagenic activities. The contamination by Alternaria species of wheat kernels, collected in Tuscany, Italy, from 2013 to 2016, was evaluated. Alternaria contamination was detected in 93 out of 100 field samples, with values ranging between 1 and 73% (mean of 18%). Selected strains were genetically characterized by multi-locus gene sequencing approach through combined sequences of allergen alt1a, glyceraldeyde-3-phosphate dehydrogenase, and translation elongation factor 1α genes. Two well defined groups were generated; namely sections Alternaria and Infectoriae. Representative strains were analyzed for mycotoxin production. A different mycotoxin profile between the sections was shown. Of the 54 strains analyzed for mycotoxins, all strains included in Section Alternaria produced AOH and AME, 40 strains (99%) produced TA, and 26 strains (63%) produced ALT. On the other hand, only a very low capability to produce both AOH and AME was recorded among the Section Infectoriae strains. These data show that a potential mycotoxin risk related to the consumption of Alternaria contaminated wheat is high.

Aspergillus flavus, the main aflatoxin B1 producing fungal species, Fusarium graminearum, a deoxynivalenol producer, and the fumonisin-producing species F. proliferatum and F. verticillioides are the main toxigenic fungi (TF) that colonize maize. Several strategies are available to control TF and related mycotoxins, such as chemical control. However, there is poor knowledge on the efficacy of fungicides on maize plants since few molecules are registered. The sensitivity of F. graminearum, F. proliferatum, F. verticillioides, and A. flavus to eleven fungicides, selected based on their different modes of action, was evaluated in both in vitro assays and, after selection, in the field. In vitro, demethylation inhibitors (DMI) showed excellent performances, followed by thiophanate-methyl and folpet. Among the succinate dehydrogenase inhibitors (SDHI), isopyrazam showed a higher effectiveness against Fusarium species than boscalid, which was ineffective against Fusarium, like the phenyl-pyrrole fludioxonil. Furthermore, both SDHIs and fludioxonil were more active against A. flavus than Fusarium species. In field trials, prothioconazole and thiophanate-methyl were confirmed to be effective to reduce F. graminearum (52% and 48%) and F. proliferatum contamination (44% and 27%). On the other hand, prothioconazole and boscalid could reduce A. flavus contamination at values of 75% and 56%, respectively.