Bacillus velezensis K-9 as a Potential Biocontrol Agent for Managing Potato Scab.

Crop pathogen infections can lead to substantial economic losses, but biocontrol, an environmentally friendly approach, can be used to control infections. For the biological management of potato scab disease, we assessed the potential use of Bacillus velezensis as a biocontrol agent. B. velezensis K-9 inhibited up to 44.90% of the infection caused by Streptomyces scabies, the causative agent of potato scab. Treatment of the S. scabies-infected potato plants with B. velezensis K-9 resulted in a significant reduction in the depth of the disease lesions compared with the untreated infected potato plants. In a radish seedling test, the B. velezensis K-9 culture and cell-free filtrate significantly reduced (P < 0.05) potato scab disease symptoms, suggesting that the strain K-9 was able to reduce S. scabies pathogenesis on potatoes. In a field test, the disease and scab indexes for B. velezensis K-9 against potato scab were significantly different from the control. In 2021, the potato yield for the B. velezensis K-9-treated plants was 12.44% higher than that for the control plants. In 2022, the potato yield following B. velezensis K-9 treatment increased by 12.65% compared with the control. In conclusion, B. velezensis K-9 prevented potato scab and increased potato yield. Thus, B. velezensis K-9 substantially reduced the occurrence of potato scab and could be used as a potential biocontrol agent for the management of potato scab.