Different strategies to control potato brown rot disease / Maryan Makram Youssef Saad ; Supervised Maurice Sabry Mikhail , Basita Abbas Hussein , Nevein Anwar Shehata Messiha

Thesis (Ph.D.) - Cairo University - Faculty of Agriculture - Department of Plant Pathology and Physiology

The aim of the present study was to evaluate the antibacterial activity of four different groups of treatments i.e., five antagonistic bacterial isolates; two speciesof trichoderma; three species of cyanobacteria and three types of Nanoparticle materials (NPs) against the growth of Ralstoniasolanacearum, the causal agent of potato brown rot disease, in vitro and their effect on the disease suppression, as well as the plant growth under greenhouse conditions. The changes in some chemical constituents of the treated plants werealso estimated. Fourteen virulent isolates of the pathogen isolated from infected potato tubers were used in this study. Identification tests confirmed that the 14 isolates belonged to R. solanacearum. In vitro experiments, five antagonistic bacterial isolates acinetobacter baumannii (PD 3138), bacillus cereus (STDF2905/31), bacillus ST1, bacillus ST2 and bacillus ST3 were suppressive to the growth of R. solanacearum. The highest inhibition zone of 12.39 mm was recorded for B. cereus.The cultural filtrates of T. harzianumand T. viride inhibited R. solanacearum growth. The higherinhibition zone diameter of 8.00 mm was recorded for T. harzianum. Three cyanobacterial species namely: Nostoc muscorum, spirulina platensis and anabaena flos-aquae were used. The most suppressive cultural filtrate, against R. solanacearum growth, was A. flos-aquae with 13.7 mm inhibition zone. Five concentrations of three Nanoparticles i.e., zinc oxide, iron oxide and alloy of both, were tested against the pathogen growth

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