Question

Puccinia graminis tritici causes:
A. Brown rust
B. White rust
C. Yellow rust
D. Black rust

Answer 1

Hint: Stem rust and cereal rust is caused by Puccinia graminis and it affects cereal crops mostly like bread wheat, durum wheat, which is mainly due to Fungus and can cause disease affecting crops.

Complete answer:
First of all you should know about all the given terms in the question. Stem rust and cereal rust is caused by Puccinia graminis tritici. It is a disease which affects cereal crops. Cereal crops which are affected by it include bread wheat, durum wheat, barley and triticale. It causes black stem rust of wheat and it is often used to illustrate the processes of infection. This disease is heteroecious which means that it required two hosts for the parasites to complete its life cycle. It is mainly stem rust of wheat, bluegrass and black rust of cereals.

So, if we look at the options now,
> Option A is Brow rust but as per the explanation above it does not cause brown rust but instead it causes black rust. Brown rust is caused by Puccinia triticina not by Puccinia graminis. So, this option gets eliminated and it is the incorrect one.

> Option B which is White rust. Puccinia graminis does not cause white rust too as it causes black rust of wheat and this white rust is caused by fungus like oomycetes So this option is also not the correct one and hence it gets eliminated too.

> Option C is Yellow rust and this option is also not the correct one as yellow rust is caused by basidiomycete fungus. Puccinia striiformis not Puccinia graminis. So, this option gets eliminated as it is also incorrect.

> Option D is Black rust and this option is the correct one as black rust is caused by Puccinia graminis tritici. It causes black stem rust on wheat.

Hence, the correct answer is option (D).

Note: Stem rust is also known as Black rust, it mainly causes disease in wheat, But also can cause slight infection or disease in other crops too like barley and rye.