Comments. Submit. More than 8,000 types of fungi have the ability to precipitate diseases in plants, according to the University of Wisconsin's Plant Pathology website. Fungi use spores to reproduce and often the spread of these spores infects a healthy plant host with the fungus, leading to the disease.Some fungal diseases such as leaf spot and powdery mildew occur in a wide variety of plants, while others such as Dutch elm disease target a particular host.omments. Submit. More than 8,000 types of fungi have the ability to precipitate diseases in plants, according to the University of Wisconsin's Plant Pathology website. Fungi use spores to reproduce and often the spread of these spores infects a healthy plant host with the fungus, leading to the disease.