Lotta chimica e biologica alla batteriosi dell'actinidia: prove in serra e in campo

In 2008 a new bacterial canker, already known in Asia, arose in Italy on kiwifruit. The disease is caused by Pseudomonas syringae patovar actinidiae (PSA). PSA is generally not invasive, but when it settles, it cannot easily be controlled. PSA spreads passively by using natural openings of the plant or by wounds created by wind, hailstorm, frost, agronomic operations, or other pathogens. The first outbreaks occurred on yellow pulp cultivars of kiwifruit, which are characterized by greater number of stomata. Evident symptoms appear on branches, with formation of cankers that produce a white or red bacterial exudate, which represents the new source of inoculum. On the leaf, PSA settles in the lower part where it spread and later penetrate inside through the stomata. Climatic factors favourable to PSA include high humidity and mild temperatures. The aim of this study was to test several commercial and experimental copper formulations, fertilizers, and reduce inducers against PSA. The evaluation was performed twice in glasshouse and once in open air. The first treatments were applied before the symptoms show up. The treatments with cooper alone and combined with acibenzolar-S-methyl showed significant results on pathogen control in open air trial. The treatments with copper, acibenzolar-S-methyl, fertilizers (potassium phosphite), resistance inducers (Fertirev), and aluminium fosetyl showed significant results on pathogen control in both glasshouse trials. The treatments with compost showed similar results to those from copper oxychloride treatment. Some phytotoxicity was detected on plants treated with copper and acibenzolar-S-methyl only in glasshouse trials. The treatments with alternative products such as essential oil, propolis, and zeolites showed also interesting results. Nowadays, prevention practices allow an evident reduction of pathogen presence and propagation of new infections.