Black rust or stem rust of wheat is caused by

Answer: Option A

Black rust or stem rust of wheat is caused by Puccinia graminis tritici.
Stem rust, also known as cereal rust, black rust, red rust, or red dust, is caused by the fungus Puccinia graminis, which causes significant disease in cereal crops.
Crop species that are affected by the disease include bread wheat, durum wheat, barley, and triticale.
Stem rust on wheat is characterized by the presence of uredinia on the plant, which are brick-red, elongated, blister-like pustules that are easily shaken off.