ISHS Acta Horticulturae 291: III International Mango Symposium
ATTEMPTS TO DEVELOP A BIOLOGICAL CONTROL OF BACTERIAL BLACK SPOT OF MANGOES. |
| Authors: | O. Pruvost, J. Luisetti |
| Abstract:
Epiphytic bacteria on mango leaves from Reunion orchards were investigated for two years to select strains antagonistic to Xanthomonas campestris pv. manqiferaindicae (X. c. pv. mi) in vitro in order to develop a biological control. Less than 20% of the isolated strains were antagonistic against X. c. pv. mi in vitro. Most of the (70%) were identified either as Bacillus subtilis or B. amyloliquefaciens. The remaining strains were Erwinia herbicola type. Experiments were then performed on detached mango leaves to determine the ability of 7 selected strains (5 Bacilli and 2 Erwinias) to colonise the leaf surface and to reduce the population level of the pathogenic bacterium in situ. The best results were obtained with the Bacillus strains. These multiplied within one week. In contrast, populations of the 2 Erwinia strains decreased quickly and did not affect the dynamics of X. c. pv. mi in situ. Further experiments were performed with only the 5 Bacillus strains using young mango plants grown in pots and kept under a plastic cover. Under these conditions the populations of antagonistic bacteria that were able to survive for at least 2 weeks on the leaf surface, significantly reduced the multiplication rate of the pathogenic strain. Moreover, a significant reduction in disease incidence occurred : 6% of infected leaves on treated plants compared to 54% for the control. Ways to improve the efficacy of such a biological method are discussed. | |
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