A study on epiphytic population of Erwinia amylovora on pear trees

This study was carried out to determine epiphytic populations of the fireblight pathogen Erwinia amylovora on blossoms and shoots of pear trees. Washings of blossoms and shoots were collected from naturally infected pear trees from to tenfold dilutions in PBS were plated onto each of 3 plates each of Ishimaru and Klos's CCT, Miller and Schrot's MS and Crosse and Goodman's CG selective media. Population on asymptomless blossoms ranged from 10(3) to 10(5) cfu/ml, shoot populations ranged from 0 to 3.1 x 10(4) cfu/ml. Symptoms were late observed on shoots due to favorable weather conditions for fireblight. Using these data some of the forecasting models were also concluded.