Bacillus thuringiensis strains that belong to B. thuringiensis, B. kurstaki and soil-isolated B.t. were assessed in the following phytopathogenic: Rhizoctonia solani, that had their mycelial growth decreased after incubation in the presence of the bacterial strains. The bacteria have also pathogenic effect against the insect pest Spodoptera littoralis. The isolate B.t. D-1 and the B.t. kurstaki HD-203 were found to be inhibiting R. solani, the strain B. kurstaki HD-203 displayed the highest percentage of inhibition (64%) and B.t. D-1 showed 49% of inhibition. Antagonistic activity was maintained up to pH 8.5, and the antifungal activity was stable to heat at 70°C for 1 h. Minimal inhibitory concentrations were 152 and 131 μl/ ml for B.t. D-1 and B. kurstaki HD-203, respectively. The two strains also have high efficacy against S. littoralis larvae, B.t.-D1 gave 70% and the B. kurstaki HD-203 strain gave 80% mortality after seven days of treatment.
The effect of Sodium bicarbonate and three oils namely; garlic, anise and mineral oil individually and combination of Sodium bicarbonate + mineral oil were tested for their effect on powdery mildew of Matricaria chamomilla under greenhouse and field conditions. Disease severity was significantly reduced by all treatments in both greenhouse and field. Flowers number in greenhouse under infection of powdery mildew disease was highly significant in treatment with NaHCO 3 + mineral oil followed by Garlic oil and NaHCO 3. Fresh weight of flowers was significantly higher in NaHCO 3 + mineral oil followed by Garlic oil (5.24 and 3.45 g) compared to control (1.7g) respectively. On the other hand, dry weight was increased significantly in treatment with NaHCO 3 followed by Garlic oil (0.81 and 0.54g) compared to control (0.21g) respectively. Effect of sodium bicarbonate and oils on flowers fresh and dry weight and plant height under natural infection of powdery mildew in the field, was significantly increased in treatment with NaHCO 3 + mineral oil followed by NaHCO 3 (663.13 and 451.13g) compared with control (220.77g); respectively. Dry weight of flowers after 2 weeks was highly significant in treatment with NaHCO 3 followed by Anise oil (120.67 and 94.33g) compared to control (41.67g); respectively. On the other hand, after 4 and 6 weeks treatment with NaHCO 3 + mineral oil was the best treatment in fresh and dry weight followed by Anise oil.
Salicylic acid (SA) and Sil-Matrix 29% SL (SM) (potassium silicate, potassium salt of silicic acid) were used to manage white rot of onion caused by Sclerotium cepivorum Berk. at the rate of 1, 2 and 3mM of SA and 1.5, 3 and 6ml/L of SM as transplants dipping followed by foliar spray by the same concentrations at 6 and 12 weeks from transplanting under greenhouse and open field conditions. The fungicide folicure 25% EC (Tebuconazole 25%) was used as comparison. All treatments reduced white rot infection compared with non-treated plants either in greenhouse or field. SA at the rate of 3mM gave the best reduction where it gave 35.0% and 26.0% infection under greenhouse and field respectively. The best treatment of SM was 6ml/L which gave 45% and 38.2% infection under greenhouse and field respectively. Compared to non-treated plants, all treatments increased onion yield, bulb weight, and plants height. SA at the rate of 3mM gave 144.3% and 160.4% increase in yield and bulb weight respectively, while SM at the rate of 6ml/L gave 24% as best increase in plants height. Soluble protein, free amino acids, reducing sugars, phenolic compounds, peroxidase and polyphenol oxidase activity increased after dipping while it varied after spraying.
Alternaria porri (Ellis). Ciffen causes serious problems in onion plants. It is transmitted with naturally infected seeds and bulbs from the previous crop to infect the new flower stalk of the next crop. Also, onion bulb infection decreases seed vitality. Infected sample were collected from four locations; Giza, Sharkia, Kalubia and Menofia governorates to measure disease severity. Experiments have been done on naturally infected seeds and bulbs from the previous year by cultivating infected bulbs. Infection was classified into five categories based on the percentage of disease severity. Pathogen transmission by the onion seed was investigated, either as internal or external infection type, Five different ratios of blub infection was determined as; 14.2%, 25.2%, 41.5%, 61.1%, 87.5%. Also, trials were carried out in the current study to evaluate the efficiency of some botanical, biological and chemical as seed dressing treatments for infected seeds before sowing it, i.e. (Achook, Bougainvillea sp., Bacillus sp., Trichoderma sp. and Score). Results showed that disease severity was increased in the blub produced from previous crop, the number of flower stalk was reduced, and its disease severity was increased. Seeds produced from infected blub showed reduction in germination percentage. The most effective seed dressing treatment on seed germination were obtained by using score & Achook treatment compared with other seed dressing treatments. All treatments including Score, Achook, Bacillus sp., Bougainvillea sp., and Trichoderma sp.; respectively showed variable seed stimulation of germination compared with plants in the control treatment.
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