FIRE BLIGHT OF PEAR IN EGYPT: CHRONOLOGICAL BACKGROUND AND NEW FINDINGS | ||||
| Egyptian Journal of Agricultural Research | ||||
| Article 3, Volume 96, Issue 4, December 2018, Page 1291-1305 PDF (871.91 K) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/ejar.2018.141440 | ||||
 View on SCiNiTO | ||||
| Authors | ||||
| NAGLAA M. BALABEL; NABIL S. FARAG; TAHA E. EL-SHARKAWY; FATEN S. MANSOUR | ||||
| Plant Pathology Research Institute, Agric. Res. Center | ||||
| Abstract | ||||
| The pear disorder described as fire blight has long been disputed in Egypt due to relatively dry climate unfavourable for the disease epidemic. Efforts were carried out in the present work to clarify the cause of confusion and to elucidate some aspects of such discrepancies. Orchards inspections in El- Behera governorate revealed obvious scorching on the foliage of some trees, without noticeable seeping under any circumstances. The syndrome disputed plant pathologists in many institutions, because of the validated absence of such scorching on apple trees raised in the same pear orchard. Samples collected from different pear organs of sporadically affected trees were subject to isolate the pathogen on either high sucrose or Miller- Schroth (MS), media selective for Erwinia amylovora. Macroscopic, microscopic, biochemical and molecular determinations revealed no obvious variation among isolates recovered from different pear tree organs. The obtained results indicated that the isolated bacteria belonged to Erwinia amylovora. Isolates from cankerous branches, however, were more pathogenic compared to those recovered from other plant organs. The rootstocks dominating in Egypt are P.communis, P.betulaefolia and P.calleryana. The effect of such rootstocks on" MKM" grafted pear cultivar was compared. The differences in the blooming date and variation in the occurrence and severity of such a disorder were evaluated. The earlier blooming, as shown influenced by the rootstock effect, the lower the disease expression. P.calleryana and P.betulaefolia showed full blooming in the third week of March, and escaped severe infection. The remarkable late onset of flowering of P.communis grafted trees commencing at the end of March, resulting in greater disease complications, due to the possible discharge of bacteria from holdover cankers, coinciding with more favourable temperature and higher insect activity. The influence of different rootstocks on growth habits of pear grafts and their respective influence on the disorders in concern must be fully investigated. The occurrence of associated microscopic mites must be seriously considered, which may be contributing to the reported discrepancy among scientists and the contradictory remarks on fire blight epidemics in Egypt | ||||
| Keywords | ||||
| Erwinia amylovora; P.communis; P.betulaefolia P.calleryana; different rootstocks; pear organs and eriophyde mites | ||||
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