Fungi imperfecti The fungi of this class mostly resemble to Ascomycetes or sometimes Basidiomycetes. Many species are
responsible for causing many diseases. The fungi of this class mostly resemble to Ascomycetes or sometimes Basidiomycetes, but they are known to produce neither asci nor basidia.
They reproduce by means of conidia which are very similar to those produced by many Ascomycetes or Basidiomycetes which have lost their ability to reproduce sexually. Thus, they lack always perfect or sexual stages. Thus, this class of fungi are known as Fungi imperfecti.
Many Deuteromycetes (Fungi imperfecti) are known to possess a parasexual cycle in which hyphal union, nuclear fusion and meiosis occur but not in a definite place or at a definite time in the life cycle. However, parasexual cycle is much less efficient, and does not produce spore fruits (e.g., ascocarps and basidiocarps) and spores (e.g., ascospores or basidiospores).
Several thousands of species of Fungi imperfecti are known. Many species are responsible for causing many diseases such as early blight of potato which is caused by Alternaria solani; red rot of sugarcane is caused by Colletotrichum falcatum; tikka disease of groundnut is caused by Cercospora personata and stripe disease of barley is caused by Helminthosporium gramineum.