Title: "Microparticles containing gallic and ellagic acids for the biological control of bacterial diseases of kiwifruit plants"
Authors: Antonio Rossetti, Angelo Mazzaglia, Massimo Muganu, Marco Paolocci, Maddalena Sguizzato, Elisabetta Esposito, Rita Cortesi, Giorgio Mariano Balestra.
The cultivation of actinidia to produce kiwis has become increasingly important in Italy as well as in various areas around the world. At the same time, however, bacterial diseases are affecting its cultivation. The most dangerous is without doubt the bacterial canker caused by Pseudomonas syringae pv. actinidiae (Pss) Takikawa et al., also known as Psa, which damages all vegetative organs.
Serious damage is caused also by the drop in temperatures in spring, as is the case this year, associated with other two bacteria - Pseudomonas syringae pv. syringae (Pv) van Hall, responsible for floral bud necrosis and Pseudomonas viridiflava (Burkholder) Dowson, the bacterial blight which affects leaves and floral organs.
In Italy, prevention is carried out by using copper salts as well as a biological control agent (B. a. subsp. plantarum ceppo D747) during blossoming. Other areas outside the EU employ antibiotics with serious repercussions on the environment and leading to the development of antibiotic-resistant bacteria strains.
This study assessed the effectiveness of gallic and ellagic acids, i.e. natural substances that are easily attainable from many vegetable tissues and with high anti-microbial properties.
These natural, active principles proved effective as pure substances both in the lab and in vivo (greenhouses, then open-field actinidia orchards naturally affected by Pss, Pv and Psa).
The vegetable active principles significantly reduced the various bacterial populations as well as the damage caused both through artificial contamination and by using them on orchards naturally affected by Pss, Pv and Psa.
In association with the intrinsic activities, the active principles proved particularly effective when employed through micro-formulations in micro-capsules, thus preventing alterations (physical-chemical) and enabling a controlled release of the principles over two weeks protecting all vegetable organs.
In addition, the activity of these formulations on both plant development and final production was also assessed. All parameters showed how these micro-formulations do not affect plant development (the plants treated with micro-capsules had a higher chlorophyll content in the leaves and the fruits, though with the same size and Brix level, were more compact).
The results obtained with this study represent a significant contribution towards the attainment of formulations that can successfully counter dangerous micro-organisms like those affecting actinidia with a sustainable/organic approach.
Reducing the use of copper salts to protect crops is a process dictated by the EU. As of January 2018, further reductions of Cu++ will be introduced, thus valid alternatives must be found.
This study suggests how gallic and ellagic acids, when formulated together in microformulations, can be successfully employed in sustainable/organic defence strategies against pathologies like those currently affecting actinidia.
The active principles and technology used in this research constitute an important base, as what described can be applied to different pathogens/ crops, thus reducing the use of chemicals and therefore chemical residue.
Additional studies are currently being carried out concerning organic nano-formulations for the protection of different crops both in the fields and during the storage and commercialisation stages. They aim at a further reduction of the (natural) active principles used, at a prolonged controlled release and at making it so that formulations can penetrate fruit/plants and target the pathogen.
Prof. Giorgio M. Balestra
DAFNE (Department for Agriculture, Forestry, Nature and Energy)
University of Tuscia
Via S. Camillo de Lellis
Tel.: (+39) 0761 357474
Cell.: (+39) 333 4246404
Fax: (+39) 0761 357473
Personal page: www.dafne.unitus.it/web/interna.asp?idPag=1118