Bioactivity and Control Efficacy of the Novel Antibiotic Tetramycin against Various Kiwifruit Diseases

Tetramycin, a novel polyene agriculture antibiotic, has excellent antimicrobial activity against many plant pathogens. In this study, the antimicrobial activities of tetramycin and conventional antibiotics on eight common pathogens and their field control efficacies against four serious diseases in kiwifruit were investigated. The results show that 0.3% tetramycin aqueous solutions (AS) exhibited the superior antibacterial and antifungal activity against Pseudomonas syringae pv. actinidiae, Pseudomonas fulva, Agrobacterium tumefaciens, Botryosphaeria dothidea, Phomopsis sp., Alternaria tenuissima, Armillariella mellea and Phytophthora cactorum of kiwifruit pathogens with EC(50) values of 1.21, 1.24, 0.72, 0.14, 0.09, 0.16, 0.06 and 0.17 mg kg(−1), respectively. These EC(50) values of tetramycin were much higher than those of conventional kasugamycin, zhongshengmycin or polyoxin. Meanwhile, 0.3% tetramycin AS possessed the good field control efficacies for canker, soft rot, blossom blight and brown spot disease of kiwifruit with 74.45, 83.55, 84.74 and 89.62%. Moreover, 0.3% tetramycin AS application notably increased fruit resistance substances contents, activated fruit superoxide dismutase and polyphenoloxidase activities, as well as remarkably enhanced fruit growth, improved fruit quality and storability. This study highlights that tetramycin can be used as a preferred alternative to conventional antibiotics in kiwifruit production.