Bacillus-based products for management of kiwifruit bacterial canker

Abstract

Pseudomonas syringae pv. actinidiae is an important pathogen of kiwifruit (Actinidia deliciosa), and bacterial canker of this host is managed by monitoring and chemical control strategies. The efficacy of the bio-pesticides Amylo-X® (based on Bacillus amyloliquefaciens subsp. plantarum strain D747) and Serenade Max® (strain QST713 of B. subtilis) was evaluated by in vitro and in vivo experiments. Both antagonists inhibited different biovars of the pathogen in in vitro assays; QST713 was more efficient than D747. The two Bacillus strains also colonized A. deliciosa flowers (c. 105-7 cfu per flower) up to 96 h after inoculation. D747 persisted on leaves (c. 104-6 cfu cm-2) up to 4 weeks after inoculation, during 2 years in Emilia Romagna and Latium regions of Italy. On flowers, the antagonists reduced pathogen populations, compared to untreated (control) flowers. On A. deliciosa and A. chinensis plants under controlled conditions, Amylo-X® reduced severity of bacterial canker, providing ca. 50% relative protection on A. deliciosa and 70% on A. chinensis. Serenade Max® was less effective, giving 0% relative protection on A. deliciosa and 40% on A. chinensis. In a field trial, on A. deliciosa plants, Amylo-X® reduced the severity of bacterial canker on leaves, providing ca. 40% relative protection. The sensitivity of both antagonistic strains to streptomycin sulphate was confirmed by testing the most used concentration where antibiotics are approved for management of bacterial pathogens.

Paenibacillus polymyxa YLC1: a promising antagonistic strain for biocontrol of Pseudomonas syringae pv. actinidiae, causing kiwifruit bacterial canker

“…7,8 Biocontrol agents have attracted increasing attention owing to their advantages of being environmentally friendly and not easily susceptible to drug resistance. To identify biocontrol agents against kiwifruit canker, Pseudomonas sp., 9 Bacillus sp., 10 Lactobacillus sp., 11 Aureobasidium sp., 12 Streptomyces sp., 13 and others have been studied and shown to inhibit Psa in laboratory tests. Formulations such as Aureo® Gold and BOTRY-Zen®have been used as biological control agents for KBC in New Zealand.…”

Antagonism and Antimicrobial Capacity of Epiphytic and Endophytic Bacteria against the Phytopathogen Xylella fastidiosa

“…The production of antimicrobial metabolites, mostly with broad-spectrum activities, has been reported for biocontrol bacteria belonging to Agrobacterium, Bacillus, Pantoea, Pseudomonas, and many other genera. Bacillus genera have been observed to produce several antimicrobial substances such as non-ribosomal lipopeptides (LPs), iturins, fengycins, surfactins, and serine proteinase subtilisin [11,12], while Pseudomonas genera have been more associated with antibiotic metabolites such as pyrrolnitrin and phenazine [13]. Indeed, the lack of any therapeutic formulation for curing infected olives further emphasizes the need to develop effective and sustainable control strategies.…”