Rust, smut and mushroom all belong to the group of pathogenic fungi. These fungi belong to the class basidiomycetes, and produce basidiospores. Mushroom are placed in the order agaricales. Amanita and Marasmius are pathogenic or disease causing fungi. Marasmius ordeades causes fairy rings on turf grasses. Rusts and smuts are included in the subclass teliomycetidae. Rust fungi comes under order uredinales, eg. Puccinia graminis causes black rust of wheat, $P$. recondita causes leaf rust of wheat. Smut fungi comes under order ustilaginales which produce teliotospores, eg. Ustilago tritici causes loose smut of wheat.