Resistance to the fungicide boscalid in laboratory mutants of Botryotinia fuckeliana (Botrytis cinerea) was investigated. The baseline sensitivity to boscalid was evaluated in terms of colony growth (EC 50 =0.3-3 µg ml −1 ; MIC=10-30 µg ml −1 ) and conidial germination (EC 50 =0.03-0.1 µg ml −1 ; MIC= 1-3 µg ml −1 ) tests. Mutants were selected in vitro from wild-type strains of the fungus on a fungicide-amended medium containing acetate as a carbon source. Mutants showed two different levels of resistance to boscalid, distinguishable through the conidial germination tests: low (EC 50 ∼0.3 µg ml −1 , ranging from 0.03 to 1 µg ml −1 ; MIC>100 µg ml −1 ) and high (EC 50 > 100 µg ml −1 ) resistance. Analysis of meiotic progeny from crosses between resistant mutants and sensitive reference strains showed that resistant phenotypes were due to mutations in single major gene(s) inherited in a Mendelian fashion, and linked with both the Daf1 and Mbc1 genes, responsible for resistance to dicarboximide and benzimidazole fungicides, respectively. Gene sequence analysis of the four sub-units of the boscalid-target protein, the succinate dehydrogenase enzyme, revealed that single or double point mutations in the highly conserved regions of the iron-sulphur protein (Ip) gene were associated with resistance. Mutations resulted in proline to leucine or phenylalanine replacements at position 225 (P225L or P225F) in high resistant mutants, and in a histidine to tyrosine replacement at position 272 (H272Y) in low resistant mutants. Sequences of the flavoprotein and the two transmembrane sub-units of succinate dehydrogenase were never affected.

In the Mediterranean basin, Verticillium Wilt of Olive (VWO) is diffused throughout its range of cultivation, causing severe yield losses and tree mortality. The disease was reported in almost all the Mediterranean and Middle East countries, and in Lebanon it is of increasing significance also on many valuable crops. The disease has already been reported on potato, peach and almond in the Bekaa valley; however, to date no information is available about the incidence of VWO and the inoculum density of Verticillium dahliae microsclerotia in soil of the main agricultural areas of Lebanon. Results from the present investigations demonstrate a high V. dahliae frequency in soils (75.3%), coupled with a mean soil inoculum density of 17.0 MS g−1, clearly indicating a great impact on the production of susceptible hosts in Lebanon, mainly in Bekaa region. Molecular method to assess the microsclerotia inoculum density in soil allowed the detection of a higher frequency of infested soils, as compared with the traditional plating, thus confirming its higher sensitivity. The overall Verticillium wilt prevalence in the inspected olive orchards was 46.2%, and the frequency of V. dahliae‐infected trees was 25.7%. The widespread presence of V. dahliae in all olive growing areas of Lebanon enforces the adoption of measures aimed at reducing the soil inoculum density before any new olive plantation, and the use of strong phytosanitary regulations to improve the certification schemes of propagating material.

The tomato is one of the most consumed agri-food products in Lebanon. Several fungal pathogens, including Alternaria species, can infect tomato plants during the whole growing cycle. Alternaria infections cause severe production and economic losses in field and during storage. In addition, Alternaria species represent a serious toxicological risk since they are able to produce a wide range of mycotoxins, associated with different toxic activities on human and animal health. Several Alternaria species were detected on tomatoes, among which the most important are A. solani, A. alternata, and A. arborescens. A set of 49 Alternaria strains isolated from leaves and stems of diseased tomato plants were characterised by using a polyphasic approach. All strains were included in the recently defined phylogenetic Alternaria section and grouped in three well-separated sub-clades, namely A. alternata (24 out of 49), A. arborescens (12 out of 49), and A. mali morpho-species (12 out of 49). One strain showed high genetic similarity with an A.limoniasperae reference strain. Chemical analyses showed that most of the Alternaria strains, cultured on rice, were able to produce alternariol (AOH), alternariol methyl ether (AME), altenuene (ALT) and tenuazonic acid (TA), with values up to 5634, 16,006, 5156, and 4507 mg kg−1, respectively. In addition, 66% of the strains were able to co-produce simultaneously the four mycotoxins investigated. The pathogenicity test carried out on 10 Alternaria strains, representative of phylogenetic sub-clades, revealed that they were all pathogenic on tomato fruits. No significant difference among strains was observed, although A. alternata and A. arborescens strains were slightly more aggressive than A. mali morpho-species strains. This paper reports new insights on mycotoxin profiles, genetic variability, and pathogenicity of Alternaria species on tomatoes.

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