The Effect of Some Plant Extracts on Pathogenic Fungi Alternaria spp. and Fusarium spp. that were Isolated from Greenhouses of Baqubah, Diyala Governorate

The development and spread of fungal infections via leaves, stems and soil in greenhouse crops poses a threat to many diverse crops due to the environmental conditions they provide, leading to economic losses. In this laboratory study, fungal species were isolated and identified from a variety of greenhouse plants, including peppers, cucumbers, chard, spinach, eggplant and strawberries. Following isolation and identification, the fungal genus Penicillium, Fusarium, Aspergillus, Alternaria and Rhizopus were identified as the cause of dark spots on the leaves of the studied plants. Alternaria spp. and Fusarium spp. fungi were used to test plant extracts and demonstrate their ability to inhibit their growth. Three aqueous extracts were tested separately: clove (Dianthus caryophllus), cinnamon (Cinnamomum verum) and ginger (Zingiber officinale) at two concentrations (25 and 50%), in addition to studying the interaction between these three plants. These extracts were tested against pathogenic fungi (Alternaria spp. and Fusarium spp.). The results showed that the aqueous extract of clove, at concentrations of 25 and 50%, achieved the highest inhibition of the radial growth of Alternaria spp. by 100%. For Fusarium spp., the clove extract also achieved the highest inhibition rate, which was 75.55% at a concentration of 25 and 88.88% at a concentration of 50%. Regarding the interaction between the extracts of the three plants, the inhibition rate of radial growth of both fungi was 100%. This opens the door to the possibility of using types of plant extracts and mixing them together to combat agricultural pests, as they contain active substances in varying proportions. When combined, they provide more inhibitory antibodies to pathogenic fungi and are used as environmentally friendly biocides.