锈菌或锈菌目(Uredinales)是植物寄生菌重要的一类,每年对农业和林业引起巨大的损失。这一类的所有锈菌都是专性寄生菌,即它们只能侵害活的植物,并在其上完成他们的发育。其它许多寄生菌,它们生活史中生长活动的一部份是在死的组织上渡过;这个时期称为腐生阶段。因为锈菌是专性寄生菌,所以它们没有腐生阶段。典型锈菌的生活史是复杂的,如五种类型的孢子产生在两种不同而且没有关系的寄主上,有些 Uredinales, an important class of plant parasites, cause huge losses to agriculture and forestry each year. All rusts in this category are obligate parasites, that is, they can only invade living plants and complete their development thereon. Many other parasites, part of their growth activity in the life cycle, pass through dead tissue; this period is called the decay stage. Because rusts are obligate parasites, they have no saprophytic stage. The life cycle of a typical rust is complex, as five types of spores are produced on two different and unrelated hosts, some