Ref rot of sugarcane is caused by

1. Anguina tritici
2. Meloidegyne incognita
3. Colletotrichum falcatum
4. Sugarcane Mosaic Virus

The correct option is 3.
Red rot is one of the major constraints in the profitable cultivation of sugarcane in many states of India. Except Maharashtra, the disease has been recorded in all the states. This disease drastically retards the yield and considerably deteriorates the juice quantity and quality thus hitting both the cane growers and millers. Many good varieties have gone out of cultivation due to red rot.

Causal organism: Colletotrichum falcatum Went, Glomerella cingulata