Question

“Red rot of sugarcane” and “white rust of radish” are respectively caused by-
A) Albugo candida and Cercospora
B) Collectotrichum and Fusarium
C) Pythium and Phytophthora
Albugo candida and Puccinia graminis
Colletotrichum and Albugo candida

Answer 1

Hint:Red rot is the most common disease of sugarcane and white rust of radishes is the common disease in radish, rapeseed, and wild mustards.The common point is that these two diseases are caused by the fungus.

Complete Answer:
Red rot of sugarcane is one of the most severe diseases of sugarcane caused by Collectotrichum, widely distributed throughout the sugar cane-growing countries of the world. The disease can be so severe that it can wipe out the sugarcane plantations in large areas. The symptoms of this disease include drooping, withering, and yellowing of the upper leaves which is followed by wilting of the entire plant shows infection and dies. At cellular level, the protoplasm changes colour due to a dark-red material which oozes out of the cells and it fills the intercellular spaces. The pigment present in this material is absorbed by the cell wall producing the characteristic red rot appearance.

The causative agent of white rust of radishes is a fungus named Albugo candida. The disease usually affects the leaves of the plant but it may affect other parts of the plant too. When the infection matures, the epidermis of the blister-like pustule ruptures due to which the powdery white spores are released. The spores are carried by wind or water for spreading the infection to other plants. Sometimes deformed stems, leaves or flowers can be observed due to the presence of pustules. Crop rotation can be used to reduce the risk of the disease by basically reducing the number of spores in the area. Plowing can also help reduce the risk but may increase the risk of soil erosion. Fungicides can also be applied to get rid of it.

Thus the correct answer is- E. Collectotrichum and Albugo candida

Note:The red rot of sugarcane appears due to pigment present in the red ooze secreted by protoplasm which gets absorbed by the cell wall producing the characteristic red rot appearance.
In white rust, the fungus is present as white pustules enclosing spores. The spots are usually observed on the ventral side of the leaves. It can only be observed in the brassicaceae family.