Sampling and isolation of the bacterial canker disease showed that the disease
occurs on branches, flowers, twigs, buds, leaves, and fruits. The most conspicuous
symptoms are the cankers that exude gum during latespring and summer on apricot,
peach and pear trees. Gumming is common on stone fruit trees, but occurs on trunks,
limbs, twigs or fruits when injuries occur. Cankerson the twigs are darkened areas
often at the base of buds. On limbs or trunks, theyare often darker than the normal
bark, sunken in their centers and they may extend for a considerable distance.
Moreover, the grown leaves and shoots may be cankered, wilted and died during the
growing season. In contrast, leaves and flowers from the other infected buds may
remain symptomless. Leaf infections appear as water-soaked spots then become
brown and dry. Fourteen bacterial isolates were isolated from different parts of peach,
apricot, pear and apple which collected from different localities of Egypt. In this
respect, the bacterial isolates coded as Pb-1, Ps-2and Pf-4 were isolated from buds,
stems and fruits respectively of peach in Daqahlyia(Mit-Ghamr). Meanwhile, the
isolates coded as Rs-3 and Lb-11 were isolated fromstem and bud of pear and apple
respectively in the same governorate (Mit-Ghamr). On the other hand, the bacterial
isolates coded as Pb-5, Pb-6, Ps-13 and Pl-15 were isolated from peach in Qualubia
governorate while, As-12 was isolated from apricot in the same governorate.
Meanwhile, the isolate coded as Rf-10 was isolated from pear in Qualubia
governorate (Moshtohor), while, the isolates coded as Pf-9 and Pb-14 were isolated
from flower and buds of peach respectively in Beheira governorate. The isolate Al-8
was isolated from leaf of apricot in the same governorate. Concerning identification
of isolated bacteria using the traditional techniques according to their inspected
morphological and cultural characteristics, these traditional tests revealed that these
isolates may be belong to three genera i.e., Erwinia, Bacillus, andPseudomonas .
Also, the other testes based on the biochemical andphysiological characteristics of
isolated bacteria revealed finally that two isolates i.e.Rs-3 and Lb-11 could be
identified asErwinia amylovora, while, the isolates i.e. Pb-6, Al-8 and Pb-14 could be
identified asPseudomonas syringae but the isolate As-12 as Bacillus polymyxa . On
the other hand, PCR-RAPD amplification by using theprimer- OP-A-11 for the three
bacterial isolates i.e.Pb-6, Al-8 and Pb-14 which identified as P. syringae by the
traditional identification verified that these three isolates are P. syringae were closely
related while three other primers proved that they may not be typical isolates. |
