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Seventeen pathogenic isolates of brown rot pathogen were collected from field soil, potato tubers, weeds and irrigation water at major potato districts in Egypt. Isolates recovered produced pink, or light red, colour with whitish margin on tetrazolium chloride medium (TZC) indicated possible virulent Ralstonia solanacearum pathogenic isolates. Pathogenicity test revealed the ability of the isolates to cause wilt symptoms in potted potato plant and three leaved tomato seedlings. Morphological, physiological and biochemical tests were used in identification. The biovar determination was made using for oxidization of disaccharides (maltose, lactose, and cellobiose) and confirmed the identity to R. solanacearum, race 3, biovar II equivalent to phylotype II, sequevar 1. A polymerase chain reaction (PCR) confirmed the identity of highest virulent isolates from tuber (T6) and from water (W11) to R. solanacearum. The application of biological agents Pseudomonas fluorescens, Bacillus subtilis, Pseudomonas aeruginosa and Trichoderma spp. decreased R. solanacearum infected plants and caused greater decrease in severity.

Blue and green molds caused by Penicillium italicum Wehmer and Penicillium digitatum Sacc. are the most important diseases affecting lime fruits. Some component of volatile oils i.e. limonene, linalool, citral and nerol were extracted from orange peel, coriander seed, lemon grass and petitgrain (Bitter orange) respectively, and were tested for their effect on linear growth of P. italicum and P. digitatum. Nerol and citral at 0.4% showed 100% reduction of linear growth. Sodium carbonate (SC) and sodium bicarbonate (SBC) showed complete inhibition on linear growth of the tested fungi at the concentration 2.0%. Effects of citral and SC or SBC singly or in combination for controlling blue and green molds of lime fruits were studied. The most effective treatments were the combined treatments between citral at 0.5% and SC or SBC at 2.0% which completely inhibited disease severity for blue and green molds of lime fruits under artificial infection and during storage for three weeks at 13± 1C. However under natural infection, the combined treatments with citral at 0.5% and SC or SBC at 2% completely inhibited percentages of infection during storage for three weeks. All treatments decreased the loss of fresh weight of lime fruit and vitamin C content but total soluble solids increased.

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