Detection of the fire blight biocontrol agent Bacillus subtilis BD170 (Biopro�) in a Swiss apple orchard

Abstract

Fire blight, caused by Erwinia amylovora, is a major disease threat to apple, pear and other pome fruit worldwide. The disease is widespread in Europe and has recently become established in Switzerland. Antibiotics are the most effective controls used in North America but these are not permitted for agricultural use in most European countries. A newly registered biological control product Biopro Ò , based on the antagonist Bacillus subtilis strain BD170, is being used as an alternative strategy for fire blight management. A specific molecular marker was developed for monitoring the spread of this agent on blossoms after Biopro Ò spray application in a Swiss apple orchard throughout the bloom period for 2 years. Direct spraying resulted in efficient primary colonisation of pistils in flowers that were open at the time of treatment. Subsequent bacterial dissemination (secondary colonisation) of flowers that were closed or at bud stage at the time of treatment was observed but was found to be dependent on the timing of treatments relative to bloom stage in the orchard. Foraging honeybees were shown to be disseminators of Biopro Ò . We also report detection of the biocontrol agent in honey collected from hives where bees were exposed by placing Biopro Ò at the entrance or in the hatching nest and from hives that were simply placed in sprayed orchards.

Antibiosis and dark-pigments secretion by the phytopathogenic and environmental fungal species after interaction in vitro with a Bacillus subtilis isolate

“…The bacterium studied has shown good antifungal activity to environmental fungi and phytopathogens, particularly by antibiosis. As expected, B. subtilis that presented biocidal effectors against fungi has been utilized as a biocontroller of phytopathogenic fungi (Broggini et al, 2005). Precipitation lines between Bacillus and fungi colonies have been reported (Cornea et al, 2003).…”

Floral traits affecting fire blight infection and management

“…Similarly, foraging honeybees were shown to be disseminators of Bacillus subtilis (Biopro Ò ), and this biocontrol agent was detected in honey collected from hives where bees were exposed to Biopro Ò and from hives that were placed in sprayed orchards (Broggini et al 2005). In comparison to the mason bee (Osmia cornuta), honeybees proved to be less efficient as carriers of the biocontrol agent Trees (2012) 26:47-66 55 B. subtilis BD170 from sprayed flowers to new ones (Maccagnani et al 2009), which is in agreement with the higher pollinating potential known for the mason bee when foraging on rosaceous plants (Monzon et al 2004).…”

“…fluorescens (BlightBan Ò A506) and B. subtilis (Biopro Ò , Serenade Ò , Micosat F Ò ) Broggini et al 2005;Elmer et al 2005;Fravel 2005;EPA 2006a, b). Yeasts or yeastlike species being evaluated in commercial preparations include Aureobasidium pullulans, Candida sake and Metschnikowia pulcherrima (Duffy et al 2006;Jelkmann and Lindner 2008;Pusey et al 2009).…”

“…The authors found that establishment and growth of C9-1S on pome fruit flowers was not strongly affected by streptomycin or by competition from indigenous bacterial epiphytes and, as with E. amylovora, temperature is an important environmental variable affecting successful spread of this biological control agent from flower to flower. Broggini et al (2005) developed a specific molecular marker for monitoring the spread of B. subtilis strain BD170, the antagonist found in the biological control product Biopro Ò . Direct spraying resulted in efficient primary colonization of pistils in flowers that were open at the time of treatment.…”

Potential for Augmentation of Fruit Quality by Foliar Application of Bacilli Spores on Apple Tree

“…Among the bacilli products, B. subtilis QST-713 produces more than 30 lipopeptide antibiotics and is marketed under the trade name Serenade; it is used mainly for the control of foliar diseases (AgraQuest, Davis, USA). Increasing numbers of bacilli strains or their metabolites have been reported to be effective in the control of foliar diseases like early leafspot, Cercospora leaf spot, grey mold and fire blight (Broggini et al, 2005;Gueldner et al, 1988;Hang et al, 2005;Kiewnick and Jacobsen, 1998;Kokalis-Burelle et al, 1992;Toure et al, 2004). The foliar application of a mixture of a *Corresponding author.…”