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Abstract Sesame (Sesamum indicum L.) plants at all their growth stages were exposed to attacked by many phytopathogenic microorganisms caused serious diseases. Root-rot and wilt diseases considered the most destructive on sesame plants causing high amounts of losses in stand plants, seed yield and seed oil content. Several studies about this subject were carried out under the laboratory. greenhouse and field conditions. The obtained results could be summarized as follow ;_ I-Several pathogenic fungi were isolated from naturalJy diseased plant materials collected from seven localities, belonging to four. Governorates of Egypt. i.e.Giza, El-Sharkia, EI-Bihiraand Beni-Suef, Among isolated fungi, A1acrophomina phascoiina was the most frequent and isolated from all localities (seven locations) followed by R. solani and F ventricosum (three locations) and F. oxysporum; F solani and S. rolfsii (two locations). 2- The isolated fungi were differed in their pathogenicities. ScleroJium rolfsi! (isolate No.2) and M. phaseolina (isolate No.7) caused the highest incidence of damping-off at seedling stage. while F oxysporum (isolate No.2) caused the highest infection with root-rot and wilt disease on standing plants. The latter two pathogenic isolates were selected if 110totherwise was indicated for further laboratory and greenhouse studies. 3- The double interaction between pairs of some pathogenic fungi grown together on agar plates showed that the growth of F oxysporum was surrounded by M phaseolin a or R. solani; but the latter two slightly inhibited each other when placed together. Sclerotium rotfstt was grown superficially over M. phaseolina or R. solani; but not inhibited their growth, while the growth of F. oxysporum was clearly inhibited with superficial growth of the first fungus. 4- Mycelial growths of M. phaseolina and F oxysporum were significantly reduced by seed and root exudates of sesame cultivar Mutation 48 more than Giza 32 cv. compared with control treatment. 5- Mycelial growth of F oxysporum was more affected by antagonistic fungi than M. phaseolina. The different isolates of Trichoderma spp., particularly T viride was the most effective in this regard followed by GliocJadium penicilloides and Chaetomium bostrycoides. 6- The effect of age and concentration of culture filtrates of different antagonistic fungi on mycelial growth of either M. phaseolina or F oxysporum showed that growth of M. phaseolina was more affected by filtrates collected after 10 and 20 days, than 30 days. The culture filtrates of Chaetomium bostrycoides and Gliocladium peniciltoides added to growth medium was more effective on mycelial growth of M. phaseolina than filtrates of the other antagonistic fungi. Effectivity of filtrates was increased with increasing their concentrations from 10.0 to 50.0%. Mycelial growth of F. oxysporum was responded similarly filtrates from 20-days-old culture was more effective than those from 10 or 30-days-old. 7- The linear growth of M. phaseolina or F oxysporum was reduced significantly with increasing concentration of different tested fungicides. However, growth of M. phaseolina was completely suppressed at concentration over than 50 ppm of Benlate and Rizolex- T and 100 ppm of Ronilan, Swnisclex and Topsin-M, whereas slight growth was observed at 1000 ppm of Monceren-Combi and Chlorothocieb, The growth of F. oxysporum was completely ’stopped at concentration of 10, SODand 1000 ppm of Benlate, Rizolex- T and Monceren-Cornbi, respectively, but the growth not completely inhibited even 1000 ppm of other tested fungicides. 8- Percentage of pre- and post-emergence damping-off and root-rot and wilt diseases was increased and healthy standing plants were decreased with increasing the inoculum amount of either M. phaseolina or F’. oxysporum from 1.250/0 up to 10.0% of soil weight. At 10.0% inoculum potential M. phaseolina killed all plants at seedling stage. 9- The percentages of damping-off disease incited by M. phaseolinu , N.. solani and S. rolfsii under greenhouse conditions were significantly equalized (60.00/0) when each of them was alone in infested soil followed by F. oxysporum (35.0%). In soils infested with different combination of these four pathogenic fungi, percentages of dampingoff disease incidence was decreased to different extant compared with M. phaseolina • R. solani or S. rolfsii each alone. The only exception in which percentage of damping-off was increased (65.00/0) was in soil infested with M. phaseolina , R. solani and F oxysporum. The incidence of root-rot and wilt, however enhanced in soil infested with M. phaseolina + S. rolfsii or R. solani + S. rolfsii and retarded in • 1 other combination particularly M. phaseolina + F oxysporum. 10·Based on percentages of healthy plants standing in infected soil under greenhouse conditions, the different tested cultivars and strains could be described highly resistant cvs. as Mutation 48 cv. and B3S strain. resistant as B10 strain. moderate resistant as Giza 32 branched and Aceteru-M cvs., moderate susceptible as Giza 32 unbranched cv., B II strain and Mutant-AM (616890) CV.~ susceptible and highly susceptible as B16 strain and B51 strain, respectively. II-Oil content in sesame seeds from root-rotted and/or wilted plants of different tested cultivars and stains due to infection with M. phaseolinu and/or F. oxy.\jJO/’U/JJ was significantly reduced seed of healthy plants grown in control (non-infested). 12- Sowing date at IS!l:!May followed by l:i! May resulted in best disease control and increased percentages of healthy standing plants grown in soil infested with M. phaseolina and/or F. oxysporum. 13- Trichoderma harzianum followed by Chaetomium bostrycoides were the best antagonistic fungi for reducing root-rot and/or wilt disease incidence and increased percentage of healthy plants compared with other antagonistic fungi. \14- Soil inoculation with vesicular-arbuscular-mycorrhyzal (VAM) fungus Glomus macrocarpum decreased percentage of damping-off and rootrot and wilt diseases caused by M. phaseolina and/or F. oxysporum . Colonization of sesame roots with different tested VAM-fungi were clearly stimulated by F. oxysporum and inhibited by M. phaseolina. 15-Benlate and Rizolex- ~ fungicides seemed to be the best fungicides for controlling disease incidence caused by M. phaseolina and F. oxysporum with clearly increasing of healthy standing plants. 16-Under field conditions, the reaction of tested sesame cultivars and strains against infection with root-rot and wilt diseases was slightly differed compared with greenhouse conditions. Aceteru-M se~ame cultivar was the most resistant, whereas Giza 32 cv. was the most susceptible. However, best seed yield was produced by 5/91 and Bl1 strs., whereas Giza 32 and Accteru-M cvs, were the least in this respect. The percentages of oil content in sesame seeds of infected plants was significantly lower than those of healthy plants. The highest seed oil content was obtained by healthy and infected plants ofB35 str.compared with other cultivars and strains. 17- Applying the highest rates of phosphatic and potassic fertilizers and lowest rate of nitrogenous one was important for decreasing disease incidence and increasing healthy standing plants and oil contents in their seeds. Combined fertilization treatment consisted of 50:300: I00 or 50:300:50 kg/fed. as urea) calcium super-phosphate and potassium sulphate, respectively were the best in ~his respect. The highest nitrogenous rate (100 kg/fed. as urea) increased or had no effect on disease incidence compared with the low rates of nitrogenous fertilizer either used alone or combined with phosphorus and potassium fertilizers. 18-Ammonium sulphate fertilizer was the best nitrogenous source for minimizing incidence of root-rot and/or wilt diseases and increased seed yield and seed yield oil content followed by organic manure) ammonium nitrate. Urea was the least effective in this regard, compared with control (without ~-fertilization). 19-Rizolex- T or Benlate as seed treatment at rate of 3 g/kg seed combined with Chlorothocieb as soil treatment at rate of 5 kg/fed. were the most effective and superior treatments for controlling rootrot and wilt diseases and increased seed yield of sesame. |