Objective Pseudomonas syringae pv. actinidiae (Psa), pathogen of the bacterial canker disease severely affecting the kiwifruit production in Fujian, was studied and effective bactericidal agents selected.
Methods Colony count on petri dishes and pathogenicity by leaf stabbing inoculation were used to determine the conditions optimal for Psa propagation. Control efficacy of 9 bactericides at the supplier’s recommended dose was observed by spraying the agents separately on the Psa-inoculated kiwifruit leaves.
Results The Psa population increased in culture at 25 ℃ at a relatively constant rate for 48-72 h but did not survive under 70 ℃ for 10 m. Either LBA or NA medium could be used appropriately for the culture, and LBA for the inoculation. The strain dependent pathogenicity of different strains of Psa, FJ02, FJ04, and FJ08, on kiwifruit and tomato leaves were substantial. Of the 9 bactericides tested, 5 were more potent: (a) 200x aqueous suspension of 6 billion Bacillus amyloliquefaciens gemmae·mL−1+ 1,000x aqueous dilution of 3% ZhongShengmycin, (b) 1,000x solution of 52% methionate·ZhongShengmycin wettable powder, (c) 500x solution of 10% kasugamycin wettable powder, (d) 1,000x aqueous dilution of 3% ZhongShengmycin, and (e) 500x solution of 18% copper rosinate emulsion. Respectively, they provided the prevention effects of 82.99%, 79.45%, 64.92%, 58.39%, and 43.97% and the control effects of 76.33%, 65.08%, 85.80%, 52.65%, and 74.85%. The germicidal treatments were deemed safe on kiwifruit leaves.
Conclusion The biological characteristics of Psa and the effective canker preventive and control bactericides for kiwifruits were successfully determined. The tested agents (a), (b), and (c) were recommended for field application.
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