Microparticles containing gallic and ellagic acids for the biological control of bacterial diseases of kiwifruit plants

Over the last decades kiwifruit cultivation has spread all over the world, and for many countries, as Italy i.e., represents a key economic resource. This plant is quite robust but some bacterial diseases can seriously threaten its cultivation. The most dangerous one is the bacterial canker of kiwifruit caused by Pseudomonas syringae pv. actinidiae Takikawa et al., but also floral bud necrosis by Pseudomonas syringae pv. syringae van Hall and bacterial blight by Pseudomonas viridiflava (Burkholder) Dowson are serious diseases of kiwifruit plants throughout the world. Their control, as for any other bacterial disease, is particularly problematic and relies mainly on antibiotics, where allowed, and copper, although this adversely affects the environment. Alternative control measures are definitely needed. Here we investigate gallic acid and ellagic acid, substances easily obtainable from some plant tissues, for their antimicrobial activity in order to use them as support in biocontrol of kiwifruit bacterial diseases. These active principles were examined firstly as pure substances both in vitro and in vivo and then, aiming to improve their effectiveness and to extend their activity in the time, they were encapsulated in polymeric microparticles. Encouraging results obtained by microformulation of both gallic and ellagic acids even in field treatments point the way to future alternative biological control strategies against kiwifruit bacterial diseases