Question

Given below are two statements, one is labelled as Assertion (A) and other one labelled as Reason (R).
Assertion (A) : Bacterial phytopathogen do cause explosive epidemics.
Reason (R) : Bacterial phytopathogens have short generation time by binary fission.
In light of the above statements, choose the correct 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:

Exponential growth driven by binary fission is the primary reason why bacterial infections can escalate from a few localized leaf spots to a field-wide epidemic within a few days when warm, wet weather occurs.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
This question focuses on the epidemiological dynamics of bacterial plant diseases.
Bacterial phytopathogens can cause devastating, rapid outbreaks (explosive epidemics) under favorable environmental conditions due to their unique reproductive capacity.

Step 2: Detailed Explanation:
Let us analyze the assertion and reason:
Assertion (A): "Bacterial phytopathogen do cause explosive epidemics."
This statement is correct.
Bacterial plant diseases, such as fire blight of apple (*Erwinia amylovora*) or bacterial blight of rice (*Xanthomonas oryzae*), can spread rapidly through entire orchards or fields within days under favorable warm, humid conditions.
These outbreaks are often sudden and highly destructive, causing explosive epidemics.
Reason (R): "Bacterial phytopathogens have short generation time by binary fission."
This statement is correct.
Bacteria reproduce asexually via binary fission, where a single cell splits into two identical daughter cells.
Under optimal conditions, many plant-pathogenic bacteria have extremely short generation times, doubling their population once every 20 to 30 minutes.
This rapid reproduction leads to exponential population growth, allowing a few initial bacterial cells to multiply into billions within a short time.
This rapid population growth drives the explosive spread of the disease across host crops, making (R) the correct explanation for (A).

Step 3: Final Answer:
Both (A) and (R) are true, and (R) is the correct explanation of (A).
This corresponds to Option (1).