Alternaria alternata and Alternaria radicina are fungal species that occur in several food crops and may produce mycotoxins and phytotoxins. The toxigenic profile of A. alternata and A. radicina isolated from carrot and other umbelliferous plants was determined by growing the fungus on rice and carrot discs. Most of the tested isolates of A. alternata produced the mycotoxins tenuazonic acid, alternariol, alternariol methyl ether and altertoxin-I on rice. Only alternariol and alternariol methyl ether were produced on carrot discs. When cultured on rice, none of the isolates of A. alternata from umbelliferous plants produced AAL toxins and fumonisins. AAL toxins, but not fumonisins, were instead produced by A. alternata f. sp. lycopersici isolate NRRL 18822 isolated from tomato. A. radicina produced the phytotoxic compounds radicinin, epi-radicinol and radicinol on carrot discs, whereas it produced radicinin and radicinol on rice. Although A. alternata has been frequently found in organic carrots, none of the above mycotoxins was detected in carrot roots or in carrot commercial products. The reduction of alternariol and alternariol methyl ether during carrot juice processing at laboratory scale was estimated to be >98%. Based on these findings and previous reports, it can be concluded that Alternaria mycotoxins in carrots do not represent a hazard for consumers.

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Milk thistle (Silybum marianum (L.) Gaertn.) is one of the most important medicinal plants. The fungi infesting its seeds may negatively influence their germination and health-promoting properties. However, there is no standard method for S. marianum seed health testing. The aim of this study was to find a suitable method for the detection and identification of fungi in/on milk thistle seeds. The following tests were used: deep-freeze blotter test, blotter test with an addition of mannitol, blotter test with an addition of polyethylene glycol, agar test on potato-dextrose agar (PDA), agar test on PDA after seed disinfection, agar test on reduced PDA and an agar test on reduced PDA after seed disinfection. Seeds were incubated for 10 and 14 days. The most prevalent fungi were: Alternaria alternata, Botrytis cinerea, Cladosporium spp., Fusarium spp., Penicillium spp., Rhizopus nigricans and Verticillium spp. A deep-freeze blotter test followed by a blotter test with an addition of mannitol and a blotter test with an addition of polyethylene glycol performed for 14 days could be recommended for the further study of milk thistle seed health testing, as they favoured the growth of the most important fungi.

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Abstract:The objective of the work was to study the efficacy of carrot seed treatment with antagonistic microorganisms Clonostachys rosea, C. solani, and grapefruit extract (Biosept 33 SL TM ). Seeds were artificially inoculated with Alternaria radicina spores prior to treatment. The presence of fungi, seed germination and vigour were determined in laboratory tests, whereas seedling emergence and health were determined in sand and soil assays. Clonostachys spp. and grapefruit extract significantly reduced seed infestation with A. radicina and improved seed germination capacity. At a lower concentration of ioculum, treatment with Clonostachys spp. increased percentage of healthy plants in sand assay. At a higher concentration of inoculum, treatment with Biosept 33 SL TM at 0.5% was more effective. Inoculation with pathogen and, in most cases, the following treatments, did not affect total plant emergence in a soil assay.However, pathogen affected significantly a percentage of healthy plants. Treatment with Biosept 33 SL TM at 0.5% as well as with C. rosea increased their numbers significantly at both concentrations of inoculum.