Abstract
Three isolates of Alternaria sp. Two of these are Alternaria alternata, one Alternaria dianthi, and three Fusarium sp. and one belonged to the type Fusarium solani, other belonged to the type Fusarium verticilliodies, the third was Fusarium oxysporum. The pathogenicity of germinating radish seeds was tested, all isolates gave varying degrees in disease severity index (DSI), as the F.verticilliodies isolate obtained pathogenicity score of (6.5), followed by isolates fungus A.dianthi has a pathogenicity index of (5.2), which means that it is highly pathogenic. As for the rest of the isolates, their pathogenicity varied. The toxic effect of the studied fungus filtrates showed clear effect on the wilting of the branches of Gerbera, Felix and Eggplant plants, compared to branches of these plants immersed in water, which indicates the toxic effect. For the infiltrates of these fungi and their pathogenic ability, local necrosis test of leaves of these plants confirmed clear pathological effects of appearance spots and cell death in pricking areas. By analyzing the absorption spectrum of fungal filtrates using the Spectrophotometer. Two peaks appeared for F.verticilliodies, as well as two absorption peaks in curves of the fungus A.dianthi and A.alternata filtrates, which indicates the toxicity of the fungus F. verticilliodies the appearance of one peak with a retention time of 2.8 minutes/sec, which indicates presence of Fumisen B1 toxin at a concentration of 0.5 µg/ml. Also, a peak was obtained with a retention time of 2.84 minutes, which indicates presence of Alternariol (AOH) toxin at concentration of 1.1 µg/ml.
