Question

Bakanae disease of Rice is due to
A. Erysiphe
B. Gibberella
C. Phytophthora
D. Albugo

Answer 1

Hint: Most of the plant diseases caused by different pathogens infect the plant and deprive it of nutrients. There are some common pathogen classes including bacteria, fungi, mycoplasma, viruses, viroids, nematodes etc.

Complete answer:
Bakanae disease was observed as a disease of rice in Asia but now observed in California since 1999. It is very damaging in Asian region but the extent of bakanae effect is unknown on the California rice production.

In the diseased plants of bakanae the plant senesce and die, mycelium of the fungus may emerge from the nodes and visible above to the water level. After draining of the water, the fungus sporulates profusely on the stems of diseased plants. Appearance of cottony mass shows the sporulation which contaminates healthy seed at the time of harvest. The bakanae pathogen can also remain in the soil and plant residue. However, infected seeds act as the most important source of inoculum.

This disease is found in Japanese plants that infects rice plants and also called as a foolish seedling. It is caused by a fungus named Gibberella fujikuroi which produces surplus of gibberellic acid, this hormone acts as a growth hormone and leads to hypertrophy in plants. The plants which are visibly etiolated and chlorotic are found infertile with empty panicles, and produce empty grains, even worse that they are incapable to handle their own weight and die.

Therefore, the correct answer is option B.

Note: The first known report of bakanae from 1828 was scientifically described in 1898 by Japanese researcher Shotaro Hori, who concluded that the causative agent was fungal. Presently, the fungus affects rice crops in Asia, Africa, and North America. At the time of epidemic cases yield losses may reach up to 20% or more.