Abstract

The bacterial antagonist Pantoea agglomerans P10c was evaluated for efficacy to control fire blight in Morocco. It was evaluated in the laboratory on detached blossoms (pre and post-inoculation of pathogen) and under field for its ability to suppress growth of Erwinia amylovora on blossoms of pear trees (Pyrus communis); and for its aptitude to establish on and to colonize the blossoms of apple tree (Malus domestica) under field conditions. Results revealed that the installation of P. agglomerans P10c strain on detached blossom before the inoculation with the E. amylovora (preventive treatment) allows an efficient control of the disease (96%), with an incidence that never exceed the level 2.5%. but for curative treatment the incidence increased to 40% and the efficiency was only about 32%. Under field, P. agglomerans P10c applied a twice (10 and 60% bloom time) at 10⁸ CFU/ml reduced significantly the incidence of fire blight by 64.7 to 76.9%. The experiment of the establishment and the survivability of P. agglomerans P10c in the stigma showed a positive evolution which increased from 4.5×10⁴ to 7.6×10⁵ CFU/flower. Results from this work illustrate that this antagonistic strain is able to control efficiently fire blight in apple  and pear trees under the conditions of the arias of Meknes.

Keys words: Erwinia amylovora, Pantoea agglomerans P10c, antagonist, blossom, preventive treatment, apple tree, pear tree, Meknes.