Question

Whip smut of the sugarcane is caused by
A) Ustilago scitaminea
B) Puccinia graminis
C) Puccinia hordei
D) Ustilago maydis

Answer 1

Hint:Whip sugarcane smut is a fungal disease that affects sugarcane and is caused by a fungus. It is called so because of the presence of black or grey growth referred whip smut.

Complete answer:
Whip smut of sugarcane is due to the outgrowth of fungus on the stalk of the sugarcane. It affects a lot of sugarcane species and some bacterial species too. The disease mainly spreads through the spores that fly through wind but it can also be caused by using infected cutting. Plants affected with whip smut of sugarcane have thin and stunted stalks. Additionally, the leaves become weaker and more slender. Let us analyze the options to find out which fungus causes whip smut of sugarcane.

Option A: Ustilago scitaminea causes the fungal disease in the sugarcane called whip smut of sugarcane. In this the fungus usually grows within the meristematic tissue. This induces the formation of flowering structures, which it colonises to produce its teliospores. Followed by this the flowering structures are transformed into a whip-like sorus that grows rapidly and protrudes out between the leaf sheaths.Therefore, this is the correct option.

Option B: Puccinia graminis is a fungus that causes ste, balck and cereal rusts which affects the cereal crops. It usually affects bread wheat, durum wheat, barley and triticale. It attacks the part of the plants that are located above the ground and in case of severe infection plants may die.Therefore, this is the incorrect option.

Option C: Puccinia hordei is a species of fungus that causes fungal infection named as barely brown rust.Therefore, this is the incorrect option.

Option D: Ustilago maydis is a member of smut fungi that mainly infects maize plants. The disease is called corn smut. Therefore, this is the incorrect option.

Thus, the correct answer is option (A) Ustilago scitaminea.

Note:The disease is known as culmicolous as it affects the stalk of the sugarcane plant. It is a widespread disease and is most common in Central and South America. For the teliospores to germinate it is important that wet climate should be there.