Distinct fungicides' in vitro, greenhouse and field efficacy on Alternaria solani, the causative agent of tomato early blight, and their effects on the biochemical components of treated plants

The study was carried out to evaluate the efficacy of three fungicides, i.e., Thiophanate-methyl (Topsin-M® 70% WP), Trifloxystrobin (Telfrec® 50% WG) and Propiconazole (Egyzole® 25% EC), used in traditional management methods on the incidence of early blight of tomato caused by Alternaria solani. The antifungal activities of fungicides against A. solani, isolated from tomato plants showing standard symptoms of early blight disease, in vitro, and their ability to suppress the disease under greenhouse as well as in field conditions were screened. In vitro, all the tested fungicides at varying concentrations reduced the linear growth of A. solani. The inhibition of fungal growth was increased with increasing concentration of all fungicides. Egyzole at 500 ppm caused the highest significant inhibition of linear growth of the fungus, followed by Telfrec. Under greenhouse conditions, spraying tomato plants with various fungicides after artificial infection of tomato plants by A. solani revealed that all tested treatments caused a significant reduction in symptoms of the disease. The effects of the tested treatments on some biochemical properties of tomato plants were also evaluated. All treatments caused changes in chlorophyll content and activities of peroxidase and polyphenol oxidase enzymes compared with control plants. In addition, the plant contents of phenolic compounds, amino acids, and proline were significantly affected.