Question

Given below are two statements, one is labelled as Assertion (A) and other labelled as Reason (R).
Assertion (A): Host resistance is one of the best methods of plant disease management
Reason (R): New pathotype can make the resistance non durable
In light of the above statements, choose the most appropriate answer from the options given below:

• A. Both (A) and (R) are true and (R) is the correct explanation of (A).
• B. Both (A) and (R) are true but (R) is NOT the correct explanation of (A).
• C. (A) is true but (R) is false.
• D. (A) is false but (R) is true.

Hint:

Host genetic resistance is the most economical and eco-friendly disease control method, but its durability is constantly challenged by the evolution of new pathogen pathotypes.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Using host plant resistance (genetic resistance) is widely recognized as the most effective and sustainable strategy for managing crop diseases.
However, plant breeders and pathologists must constantly monitor the durability of this resistance because pathogens can mutate and evolve rapidly.

Step 2: Detailed Explanation:
Let us analyze both statements:
- Assertion (A) is true: Host plant resistance is one of the best methods for managing plant diseases.
It is highly cost-effective for farmers, leaves no toxic residues in the environment compared to chemical pesticides, and is easy to adopt on a large scale.
- Reason (R) is true: Pathogen populations can evolve quickly under selection pressure.
A new pathotype (or physiological race) can arise via mutation or recombination that overcomes the host's resistance gene (especially monogenic, vertical resistance).
This causes a "breakdown of resistance," making it non-durable over time.
Although both statements are correct, the fact that new pathotypes can overcome host resistance does not explain *why* host resistance is one of the best methods of disease management.
Instead, it highlights a limitation and challenge of using host resistance.
Therefore, (R) is not the correct explanation of (A).

Step 3: Final Answer:
Hence, the correct option is (B).