Assessing the diversity of post-harvest pathogens on Swiss beetroot and evaluating the efficacy of pre-harvest treatments on storage diseases
2023
Härri, Tobias
In Switzerland, the consumption of organic vegetables, including organic beetroots, is increasing. Their prolonged storage leads to increased post-harvest losses over time due to rots, resulting in higher imports. To address this issue of storage rots, the present study examined the diversity and frequency of various pathogen species and investigated the effects of different cultivars and treatments. Infected beetroots sorted from storage were used to isolate the fungi. Their DNA was extracted, and species were identified through Sanger sequencing and comparison with the NCBI database. Nineteen different genera of storage pathogens were identified on the beetroots, with Phoma betae being the predominant pathogen, accounting for 55% of the samples. Unexpectedly, the genus Plectosphaerella, not previously described as a beetroot pathogen, was also prominently present. Compared to the previous season, there was a notable increase in the occurrence of Phoma. The three most prevalent pathogen genera Phoma, Plectosphaerella, and Fusarium remained dominant. The different treatments had only marginal or no positive effect on beetroot health compared to the control group, allowing limited comparisons between treatments. Differences in the number of diseased beetroots were observed between the two cultivars Betty and Boro, but P. betae was the predominant pathogen in both. The results imply that a control strategy against P. betae should be prioritized. The three main pathogen genera were predominantly soil-borne, suggesting a more in-depth investigation of the soil.
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