Articles
Bacillus amyloliquefaciens subsp. plantarum I3 and I5 growth characterization and activity against brown rot in peach
Article number
1256_39
Pages
281 – 288
Language
English
Abstract
Brown rot caused by the Monilinia genus, mainly by M. fructicola and M. laxa is the major pre- and postharvest decay in stone fruit in Spain.
Biological control agents (BCAs) have been recently used trying to replace or employed together with the chemicals applied in the pre- and postharvest phase.
Thus, a wide characterization of the biological control agents (BCAs) in terms of their growth at different temperatures and pHs and in presence of fungicides are previous and necessary steps in establishing the viability of BCAs.
Therefore, two strains belonging to B. amyloliquefaciens subsp. plantarum (I3 and I5) have been studied.
Firstly, temperature, pH and compatibility with six broadly active substances included in commonly used fungicides were determined in vitro followed by an in vivo growth study in peaches (pH 5.2) at room (20°C) and cool (4 and 10°C) temperatures.
Then, the efficacy against M. fructicola and M. laxa in Calante peaches was also conducted by wound and spray inoculation.
The results showed that the BCAs were mesophilic (30-37°C) and not tolerant to acidity (pH>5) but that they can survive at pH<5 and 20°C by forming spores and can germinate when the conditions are suitable for their multiplication.
Active substances such as iprodione and diethyl dithiocarbonate required 4-fold dilution whilst tebuconazole needed half concentration, comparing to reference doses.
Otherwise, phthalimide, fenhexamid and methylthiophanate allowed a proper BCAs growth at their reference doses.
All the BCAs were able to grow in peaches at 20°C and their populations remained stable at cool temperatures.
No incidence of brown rot in wounded and treated peaches were detected after 2 days at 20°C and it was significantly reduced after 5 days.
These results show the great efficacy of I3 and I5 against brown rot in peaches by reducing significantly the incidence of the disease.
This efficacy added to the compatibility with fungicides will allow a future pre- and postharvest application.
Biological control agents (BCAs) have been recently used trying to replace or employed together with the chemicals applied in the pre- and postharvest phase.
Thus, a wide characterization of the biological control agents (BCAs) in terms of their growth at different temperatures and pHs and in presence of fungicides are previous and necessary steps in establishing the viability of BCAs.
Therefore, two strains belonging to B. amyloliquefaciens subsp. plantarum (I3 and I5) have been studied.
Firstly, temperature, pH and compatibility with six broadly active substances included in commonly used fungicides were determined in vitro followed by an in vivo growth study in peaches (pH 5.2) at room (20°C) and cool (4 and 10°C) temperatures.
Then, the efficacy against M. fructicola and M. laxa in Calante peaches was also conducted by wound and spray inoculation.
The results showed that the BCAs were mesophilic (30-37°C) and not tolerant to acidity (pH>5) but that they can survive at pH<5 and 20°C by forming spores and can germinate when the conditions are suitable for their multiplication.
Active substances such as iprodione and diethyl dithiocarbonate required 4-fold dilution whilst tebuconazole needed half concentration, comparing to reference doses.
Otherwise, phthalimide, fenhexamid and methylthiophanate allowed a proper BCAs growth at their reference doses.
All the BCAs were able to grow in peaches at 20°C and their populations remained stable at cool temperatures.
No incidence of brown rot in wounded and treated peaches were detected after 2 days at 20°C and it was significantly reduced after 5 days.
These results show the great efficacy of I3 and I5 against brown rot in peaches by reducing significantly the incidence of the disease.
This efficacy added to the compatibility with fungicides will allow a future pre- and postharvest application.
Authors
H. Calvo, J. Navarro, I. Mendiara, D. Blanco, R. Oria, M.E. Venturini
Keywords
Monilinia spp., B. amyloliquefaciens, biocontrol, peaches
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