Fire blight has been a serious problem and destructive disease in pear
orchards. The first appearance of the disease at Mammal EI-Kezaz in the region
between Alexandria and Damanhur provinces was proved in 1964. However, in 1982
sever outbreak of fire blight in the Nile Delta of Egypt was noticed. The disease spread
rapidly in most governorates and as a consequence of the disease numerous orchards
has been eradicated.
The identification of twenty-three isolates obtained during this study was
preformed by traditional bacteriological tests, BIOLOG system and serological
techniques (dotimmunobinding assay, DIA and immunoflourescens test, IF). Diseased
pear tissues with typical fire blight symptoms showed positive reaction with DIA and IF
using the specific antiserum of Erwinia emyaovcre.
All tested chemical compounds and antibiotics decreased growth of E. Amy%vora and
disease severity on immature pear fruitlets, in vitro. Starner 20% (oxolinic acid) and
nalidixic acid 20% were the most effective on the growth of E. Amy/ovora and disease
severity. Meanwhile, Kocide 101, Kocide 2000, Copper oxychloride 50%, Agrimycin 17,
(Strptomycin sulfate), Apromycin 20% were moderately effective and Kasugamycin was
less effective.
Field experiments were conducted using Le Conte pear cultivar during 2001,
2002 growing season at Kalubia governorate. Int&gration between organic manure,
mineral fertilizers (NPK) and Agrimycin 17 or Starner 20% greatly reduced the number
of infected clusters and significantly increased pear yield compared with the control
treatment. No differences were found between the copper compounds which used
spraying in dormancy stage. In order to develop a management strategy to control fire
blight in orchard., an integrated approach was adopted using organic manure, mineral
fertilizers and bactericides during blooming.