Fermentation: An Unreliable Seed Treatment for Bacterial Fruit Blotch of Watermelon.

is a seedborne pathogen that causes bacterial fruit blotch (BFB), a global threat to watermelon production. Treating watermelon seeds to eliminate is a critical component of BFB management, and several strategies have been evaluated to mitigate the impact of the disease. In China, watermelon seed producers routinely incubate seeds in watermelon juice (fermentation) to reduce the risk of seed infection by and seedling transmission of BFB. However, there has been limited effort to evaluate the efficacy of fermentation in mitigating seed infection. The current study showed that fermented watermelon fruit juice could inhibit population growth and demonstrated that the low pH conditions, not the temperature dynamic, generated during fermentation might play a major role in growth inhibition and could induce the viable but nonculturable (VBNC) state in . We developed an effective method that was based on propidium monoazide PCR to detect viable cells under low pH conditions or in fermented watermelon fruit juice. We also provided evidence that VBNC cells induced by fermented watermelon fruit juice could not be resuscitated and did not retain their virulence on watermelon seedlings. However, VBNC cells could be resuscitated in Luria-Bertani medium. Based on these observations, we conclude that fermentation in watermelon fruit juice may not be an effective seed treatment for BFB because it may increase the seed infection by .