ABSTRACT
Fungi are an extremely diverse group of organisms with about 250,000 species widely distributed in essentially every ecosystem. The total weight of fungi on earth has been estimated as 4 × 1014 g, thus exceeding that of humans. In contrast to the situation in animals, in which fungal diseases are less frequent, many plant diseases are caused by fungi. Approximately 120 genera of fungi, 30 types of viruses, and 8 genera of bacteria are responsible for more than 11,000 diseases that have been described so far in plants.
