What is UG99 Wheat Rust?

Wheat Stem Rust is a major disease of wheat crops and spread by UG99 fungus. Reddish-brown flakes on plant stalks are produced by Ug99 fungus. Fungus UG99 effects wheat crops and is spreading rapidly around the world so scientists fear that it will destroy nearly all wheat crops of the world. A large number of people are dependent on wheat for nourishment so the scientists are worried about this