Question

Monocyclic diseases are incited by soilborne pathogens
(A). Monocyclic diseases are usually observed in perennial crops
(B). Monocyclic disease complete one life cycle in a year
(C). Monocyclic disease can be controlled by soil treatment
(D). Monocyclic diseases are usually endemic in a particular location
Choose the correct answer from the options given below:

• A. (A), (B) and (D) only.
• B. (A), (B) and (C) only.
• C. (B), (C) and (D) only.
• D. (A), (B), (C) and (D) only.

Hint:

Monocyclic diseases lack secondary spread within a single season. Because they are caused by soilborne pathogens, soil sanitation and rotation are primary control strategies.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Plant diseases can be classified as monocyclic or polycyclic based on the number of disease cycles they complete per cropping season.
Monocyclic diseases complete only one disease cycle per season, relying entirely on primary inoculum with no secondary spread within the same crop cycle.

Step 2: Detailed Explanation:
Let us analyze the properties of monocyclic diseases:
Statement (A) is correct: Many monocyclic diseases affect long-lived perennial crops (e.g., vascular wilts like Dutch Elm disease, or root rots in orchard trees).
Since the host is present year-round, the pathogen slowly builds up over multiple years through a single annual cycle of infection.
Statement (B) is correct: By definition, monocyclic pathogens complete exactly one life cycle (or infection cycle) per year or growing season.
There is no secondary inoculum (like asexual spores) produced that can spread and initiate new infections within the same season.
Statement (C) is correct: Because monocyclic diseases are primarily caused by soilborne pathogens (such as Fusarium oxysporum or Verticillium dahliae) that rely on primary soil inoculum to infect, soil treatments are highly effective control measures.
These treatments include soil solarization, chemical fumigation, steam sterilization, and crop rotation.
Statement (D) is correct: Soilborne pathogens have limited mobility in the soil matrix.
As a result, monocyclic diseases tend to be highly localized or endemic to specific fields or locations where the soil has become contaminated over time.
Since all four statements are correct, Option (D) is the correct choice.

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