Question

Arrange the following events prior to spread of the pathogen of the crop from the start:
A. Recognition and acceptance by susceptible host.
B. Contact with host
C. Dispersal
D. Pathogen survival
E. Primary inoculum

• A. A, B, C, D, E
• B. B, C, A, D, E
• C. C, A, D, B, E
• D. D, E, C, B, A

Hint:

A disease cannot start unless the pathogen survives the winter/summer first. Always look for "Survival" as the logical first step in a disease cycle.

Answer 1

The Correct Option is D

Concept: The disease cycle involves a chain of events that leads to the infection and spread of a pathogen within a crop population.

Step 1: Identify the starting point of the cycle.
The cycle begins with the Pathogen survival (D) during the off-season, often in soil or plant debris. This surviving population becomes the source for the Primary inoculum (E).

Step 2: Follow the physical movement to the host.
The primary inoculum must undergo Dispersal (C) via wind, water, or vectors to reach a new crop. Once dispersed, it makes physical Contact with host (B).

Step 3: Identify the final pre-infection stage.
After contact, there is a biochemical Recognition and acceptance by susceptible host (A), which triggers the actual infection process. Thus, the sequence is D-E-C-B-A.