Biological and Chemical Control of Some Tomato Fungal Diseases

Abstract

IN RESPONSE to environmental and health concerns about the extended use of pesticides, it exists a considerable interest in finding alternative control approaches. The current study compared the antifungal activities of some biocontrol agents. Three fungal strains were isolated from infected tomato. Two belonged to genus Aspergillus and the third was Fusarium sp. Ten morphologically different bacterial strains were isolated from intact tomato roots and rhizospheric soils, they were screened for their antagonistic effects against the fungal isolates. Achromobacter xylosoxidans produced the most potent antifungal activity as indicated by the percentage of fungal weight loss recorded (equivalent to 73, 77, and 99% for Aspergillus sp. 1, Fusarium sp., and Aspergillus sp. 2, respectively). Four tested plants: Inula (Dittrichia viscosa), Onion (Allium cepa), Basillic (Ocimum basilicum), and Quinoa (Chenopodium quinoa) were tested for their antifungal activities against the isolated fungal pathogens. Inula extract showed the highest inhibition of fungal growth among the tested plants. The MIC values were evaluated for the tested biocontrol agents and compared with the standard antifungal chemicals: Between and Logico. In vivo study was performed using seedlings of Tomato (Solanum lycopersicum). The seedlings infected with the fungal pathogens using spraying technique showed severe symptoms of fungal disease, while the tomato plants infected with fungal pathogens and treated with the biocontrol agents (cell-free supernatant of A. xylosoxidans or Inula extract) exhibited observed reduction in the percentage of disease severity.