Pyrenophora tritici-repentis (telomorph) and Dreshslera tritici-repentis (anamorph) is a necrotrophic plant pathogen of fungal origin Phylum Ascomycota. The pathogen causes a disease commonly called tan spot, yellow leaf spot, yellow leaf blotch or helminthosporiosis. At least eight races of the pathogen are known to occur based on their virulence on a wheat differential set.The tan spot fungus was first described in 1823 and was identified in Europe, the USA, and Japan in the early 1900s. The disease is one of the most important fungal disease on wheat and the fungal pathogen is found to infect in all parts of the world wherever wheat and other susceptible host crops are found. P. tritici-repentis overwinters on stubble, and due to recent heavily no-till/residue retention cultural practic