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Composts are known to contain beneficial bacteria, which may be antagonistic to plant pathogens. This work evaluated whether carrot white mould, causal agent Sclerotinia sclerotiorum, can be reduced using antagonistic bacteria isolated from forestry compost. In vitro and in vivo experiments demonstrated that bacteria from the genera Pseudomonas and Bacillus can inhibit mycelial growth and reduce white mould. Bacillus subtilis strains F9–2 and F9–12 and Pseudomonas arsenicoxydans strain F9–7 showed the highest inhibitory properties. Three cyclic dipeptides (diketopiperazines) were characterized from the antifungal culture filtrates of P. arsenicoxydans F9–7. When assayed against S. sclerotiorum, the diketopiperazines showed the following inhibitory activity, in increasing order: cyclo-(l-Pro-l-Val), cyclo-(l-Pro-l-Phe) and cyclo-(l-Pro-l-Leu). The combination of these diketopiperazines indicated additive and, occasionally, synergistic antifungal effects. These results indicated a potential for some bacteria to inhibit the growth of S. sclerotiorum and reduce its associated disease on carrots postharvest. [ABSTRACT FROM AUTHOR] more...

Seabirds are globally recognized vectors of marine-derived materials, which get deposited on land at their breeding colonies, potentially altering local soil chemistry. We studied mercury (Hg) in soil cores on two islands in west Iceland that host thousands of nesting seabirds, predicting that Hg subsidies from nesting birds would result in elevated Hg in local soils. However, despite clear evidence from nitrogen isotopes of marine influence (seabird faeces) on coastal soil cores, O horizon Hg concentrations averaged 223 nanograms per gram (ng/g), were similar between reference and seabird-nesting sites, and were within the range of soils elsewhere in Europe and the Arctic. The concentration of Hg declined for samples deeper in the core, mirroring declines in organic content and concomitant increases in stable isotopes of nitrogen. A more detailed analysis of local pedogenic processes is required to determine the relative contribution of lithogenic, atmospheric, and anthropogenic Hg, but our data do not suggest that seabirds are markedly increasing local soil Hg through ornithogenic subsidies. [ABSTRACT FROM AUTHOR] more...

Carrot ( L.) chromosomes are small and poorly differentiated in size and morphology. Here we demonstrate that fluorescent in situ hybridization (FISH) signals derived from arbitrary PCR probes can be used for chromosome identification in carrot. To prepare probes, we searched for nonpolymorphic products abundantly amplified with arbitrary decamer primers in a group of accessions representing carrot genetic diversity. As a result, 13 fragments ranging in size from 517 to 1758 bp were selected, sequenced, and used as probes for fluorescent in situ hybridization. Four of these probes produced clear and reproducible hybridization signals. The sequences showed similarity to a number of carrot BAC-end sequences, indicating their repetitive character. Three of them were similar to internal portions of gypsy and copia LTR retrotransposons previously identified in plants. Hybridization signals for the four probes were observed as dotted tracks on chromosomes, differing in distribution and intensity. Generally, they were present in pericentromeric and (or) interstitial localizations on chromosome arms. The use of the four probes allowed discrimination of chromosome pairs and construction of more detailed karyotypes and idiograms of carrot. [ABSTRACT FROM AUTHOR] more...

The article presents a study on disease progression of sclerotinia rot of carrot resulting from Sclerotinia sclerotiorum from shoot to root before and after harvest. Histopathology of sclerotinia rot was investigated. Petioles of greenhouse-grown carrots were inoculated with mycelium of S. sclerotiorum. Disease progression between carrots in greenhouse and cold storage was analyzed. Result showed that cellular staining appeared rarely and leaf abscission did not occur in carrots placed in cold storage. more...

The article discusses the study of differential in production of sclerotia by Sclerotinia sclerotiorum from Alaska. The study involved the isolation of Sclerotinia sclerotiorum from lettuce that were grown in Alaska and inoculation to cabbage, lettuce, carrots, and celery. Findings of the study include the distinct rDNA intergenic spacer sequences between isolate A, which matches different isolates from US and Canada, and isolate B, which matches isolates from US, Canada, and New Zealand. more...

The article discusses the integration of disease monitoring, reduced fungicide practices, and host resistance for managing carrot foliar diseases. A study is conducted on the efficacy of combined pest management on two carrot foliar diseases, Alternaria dauci and Cercospora carotae. The study findings revealed that symptoms of foliar diseases in cultivars 'Gold King' and 'Carson', and that fungicide application intervals could be lengthened from 1 to 2 weeks without compromising disease control. more...