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ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Foodborne Toxin Detection and Prevention Research » Research » Publications at this Location » Publication #357878
Research Project: Biocontrol Interventions for High-Value Agricultural Commodities

Location: Foodborne Toxin Detection and Prevention Research

Title: Comparison of Aspergillus section Nigri species populations in conventional and organic raisin vineyards

Author
item Palumbo, Jeffrey - Jeff
item O Keeffe, Teresa
item QUEJARRO, BABY JOY - Former ARS Employee
item YU, ALAN - Former ARS Employee
item ZHAO, ALISON - Former ARS Employee

Submitted to: Mycotoxin Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/26/2019
Publication Date: 5/9/2019
Citation: Palumbo, J.D., O'Keeffe, T.L., Quejarro, B., Yu, A., Zhao, A. 2019. Comparison of Aspergillus section Nigri species populations in conventional and organic raisin vineyards. Mycotoxin Research. 76(7):848-854. https://doi.org/10.1007/s00284-019-01697-6.
DOI: https://doi.org/10.1007/s00284-019-01697-6

Interpretive Summary: Species belonging to Aspergillus section Nigri are widespread in the vineyard environment, both in soil and on plant surfaces. We used plate counts and droplet digital PCR (ddPCR) methods to compare populations of the four most prevalent species (A. carbonarius, A. niger, A. welwitschiae and A. tubingensis) over two consecutive years in conventional and organic vineyards, to determine whether management affects the potential distribution of mycotoxigenic Aspergillus species. In 2016, plate counts showed that soil populations of total filamentous fungi and of Aspergillus section Nigri species were not significantly different between conventional and organic vineyards. In 2017, while total fungal populations in soil were not significantly different, Aspergillus section Nigri populations were significantly higher in organic vineyard soil. In both years, there were no significant differences in total fungal populations and in Aspergillus section Nigri populations on fruit surfaces collected from conventional and organic vineyards. Likewise, ddPCR methods did not show significant differences in percent distribution of Aspergillus species in soil and fruit between conventional and organic vineyards. These results suggest that intervention strategies for preharvest control of potential mycotoxigenic fungi are likely to be equally compatible with either vineyard management strategy.

Technical Abstract: Black-spored Aspergillus fungi are commonly found in the grape environment, in soil and on the grapes themselves. Using a combination of microbiological methods and quantitative PCR methods, we studied whether the populations of these potential toxin-producing fungi are different in organic vineyards vs conventionally farmed vineyards. Over two consecutive growing seasons, we found no differences in the population size or proportion of four Aspergillus species on fruit from these vineyards. This suggests that the effectiveness of any strategy to reduce Aspergillus populations and the possible toxin contamination of fruit caused by these fungi should not be different based on vineyard management method.