Fusarium sambucinum: causing dry tuber rot of potatoes

Among the 140 isolates collected from symptomatic potato tubers in four different European regions of Russia in 2021–2022, as many as 37.8 % isolates were identified as Fusarium sambucinum. Randomly selected isolates (n=19) of F. sambucinum were identified with DNA sequence data of the TEF locus and morphological characteristics on nutrient media. The growth rate of strains on potato-sucrose agar was assessed in the temperature range of 5–35 °C. The temperature optimum for growth of all strains was set at 25 °C, the average growth rate of strains was 13.68 ± 0.67 mm/day. The upper critical temperature completely arresting growth of strains was 35 °C, while at the temperature of 5 °C the strains were still able to grow at an average rate of 0.85 ± 0.27 mm/day. Fusarium sambucinum strains were characterized by their ability to produce symptoms of rot in potato tubers after inoculation and further incubation at 5 and 23 °C. Most strains caused extensive necrosis at the higher temperature, but there were strains whose aggressiveness was not affected by temperature. There is no clearly defined relationship between the origin of F. sambucinum strains and their aggressiveness.