Characterization of burkholderia [pseudomonas] solanacearum isolates causing bacterial brown rot of Potato in Minia and their effects of Potato cultivars

The causal bacterial pathogen was isolated from brown rot of potato tubers collected from different fields in Menia Governorate. The isolated bacteria caused wilt to potato plants and brown rot to tubers when experimentally inoculated into potato plants and grown in pots. The bacterial isolates were compared for their pathogenicity and differences in the specific symptoms induced in different hosts. They were also compared on the basis of the results of the physiological and biochemical tests and for pathogenicity to eight different hosts. Following Hayward's classification, the isolated bacteria were identified as Burkholderia [Pseudomonas] solanacearum Biovar III. Furthermore, on the basis of pathogenicity tests, the isolated bacteria were placed in race 2 of Burkholderia [Pseudomonas] solanacearum. The investigation of the effect of the isolated bacteria on ten potato cultivars revealed that cultivars Alpha, Dimonta, Gigant and Turbo were highly susceptible; whereas cultivars Accent, Agria, Aziza, Desia, Gazria and Mirakel showed a moderate susceptibility to infection with the isolated bacteria. The disease severity under the environmental conditions of summer and autumn seasons was compared

Susceptibility of certain varieties and genotypes and control of wilt and root rot diseases of sesame attributed to fusarium oxysporum f sp sesami and macrophomina phaseoli.

Eight fungal isolates were obtained from naturally diseased sesame plants suffering from wilt and root rot diseases. These isolates were identified as Fusarium oxysporum f. Sp. Sesami and Macrophomina phaseoli. Fusarium isolates infected sesame plants causing wilt symptoms and Macrophomina isolates infected sesame plants causing root rot and charcoal stem rot. Varietal resistance on different varieties and genotypes revealed that Giza 32 was less susceptible to infection with F. oxysporum and M. phaseoli than other tested cultivars. Among the tested fungicides, Benlate was the most toxic in vitro. Furthermore, the application of Benlate and Rhizolex-T as soil treatment at concentrations of 0.04-0.1% decreased the percentage of wilt and root rot diseases. Additionally, in a field trial, Benlate proved to be a very effective fungicide in decreasing infection with M. Phaseoli and F. oxysporum when applied at 0.5 g/hill. Bacillus subtilis was isolated from the rhizosphere of sesame plants and showed inhibitory effect against the fungi tested in vitro. The antagonists were able to suppress wilt and root rot diseases when applied to artificially infested soil. Moreover, the addition of 1% organic manure resulted in a greater reduction in infection with wilt and root rot diseases