This work was carried out to confirm and/or evaluate the efficacy of three Pseudomonas spp. strains against fire blight (Erwinia amylovora), southern bacterial wilt of tomato (Ralstonia solanacearum), bacterial spot/canker of stone fruits (Xanthomonas arboricola pv. pruni) and grapevine crown gall (Agrobacterium vitis). In the laboratory, there was a trend towards a higher colonisation of apple and pear flowers when Na-alginate (0.5%) was added to suspensions of freeze-dried cells of wild-types and rifampicin-resistant mutants of IPV.-BO G19 (P. putida) and IPV.-BO 4027C (a non-fluorescent Pseudomonas sp.) strains; E. amylovora populations on apple flowers were significantly reduced by strain IPV.-BO 4027C. In a field experiment, performed on actively growing shoots of pear scions ‘Abbé Fétel’ during Spring-Summer 2005, different treatments were also tested, including copper compounds the resistance inducers prohexadione-Ca (Regalis) and acibenzolar-S-methyl (Bion), and Serenade and BS-F4 (both based on Bacillus subtilis) etc. The strain IPV.-BO G19 plus Na-alginate was the most effective in reducing shoot blight incidence by 65% six weeks after wound inoculation with E. amylovora. A virulent R. solanacearum bv. 2, race 3 strain was inhibited by both these antagonists in vitro. When the pathogen was inoculated 48 h after their application (approx. 108 cfu/ml) to the root apparatus of tomato plants grown in a climatic chamber, bacterial wilt progression rate was clearly reduced; in particular, the strain IPV.-BO G19 was able to delay symptom expression and to reduce disease incidence by 100% and 37%, 9 and 21 days after inoculation, respectively. Under glasshouse conditions, BS-F4, Bion and IPV.-BO G19 reduced relative incidence of grapevine crown gall by 58%, 54% and 48%, respectively. The IPV.-BO G19 strain was also effective against X. arboricola pv. pruni: when sprayed on plum fruitlets it reduced disease incidence by 90% eight days after experimental inoculation with the pathogen.
Biological control agents as tools against some emerging bacterial plant diseases in Italy: a concrete perspective?
BIONDI, ENRICO;BINI, FEDERICA;LANCIONI, PIETRO;BRUNELLI, AGOSTINO;BAZZI, CARLO
2006
Abstract
This work was carried out to confirm and/or evaluate the efficacy of three Pseudomonas spp. strains against fire blight (Erwinia amylovora), southern bacterial wilt of tomato (Ralstonia solanacearum), bacterial spot/canker of stone fruits (Xanthomonas arboricola pv. pruni) and grapevine crown gall (Agrobacterium vitis). In the laboratory, there was a trend towards a higher colonisation of apple and pear flowers when Na-alginate (0.5%) was added to suspensions of freeze-dried cells of wild-types and rifampicin-resistant mutants of IPV.-BO G19 (P. putida) and IPV.-BO 4027C (a non-fluorescent Pseudomonas sp.) strains; E. amylovora populations on apple flowers were significantly reduced by strain IPV.-BO 4027C. In a field experiment, performed on actively growing shoots of pear scions ‘Abbé Fétel’ during Spring-Summer 2005, different treatments were also tested, including copper compounds the resistance inducers prohexadione-Ca (Regalis) and acibenzolar-S-methyl (Bion), and Serenade and BS-F4 (both based on Bacillus subtilis) etc. The strain IPV.-BO G19 plus Na-alginate was the most effective in reducing shoot blight incidence by 65% six weeks after wound inoculation with E. amylovora. A virulent R. solanacearum bv. 2, race 3 strain was inhibited by both these antagonists in vitro. When the pathogen was inoculated 48 h after their application (approx. 108 cfu/ml) to the root apparatus of tomato plants grown in a climatic chamber, bacterial wilt progression rate was clearly reduced; in particular, the strain IPV.-BO G19 was able to delay symptom expression and to reduce disease incidence by 100% and 37%, 9 and 21 days after inoculation, respectively. Under glasshouse conditions, BS-F4, Bion and IPV.-BO G19 reduced relative incidence of grapevine crown gall by 58%, 54% and 48%, respectively. The IPV.-BO G19 strain was also effective against X. arboricola pv. pruni: when sprayed on plum fruitlets it reduced disease incidence by 90% eight days after experimental inoculation with the pathogen.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
