Question

Which of the following causes "Dead heart symptom" in the standing maize crop?
A. Army worm
B. Ear worm
C. Stem borer
D. Cut worm
Choose the correct answer from the options given below:

• A. A and C only
• B. B only
• C. C only
• D. B and C only

Hint:

The "dead heart" symptom in maize is caused by the stem borer (Chilo partellus) tunneling through the stem and destroying the central growing point of the plant.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Visual damage symptoms help farmers and agronomists identify insect pests in the field.
A "dead heart" is a classic symptom caused by boring insects that tunnel into the stem of a plant.
This tunneling severs the vascular system of the central growing shoot, causing it to wither and die while the older outer leaves remain green.

Step 2: Detailed Explanation:
In maize, the primary pest responsible for the "dead heart" symptom is the maize stem borer, Chilo partellus (C).
The young larvae first feed on the tender leaves, creating characteristic "shot-hole" symptoms.
As they mature, the larvae bore into the stem and tunnel downward.
If they damage the central growing point (the apical meristem), the flow of water and nutrients to the central leaf whorl is cut off.
This causes the central leaves to dry up and die, forming the characteristic "dead heart."
This symptom is easily recognized because the central shoot can be easily pulled out and often emits a foul odor due to secondary bacterial rot.
Other pests listed cause different types of damage:
- Armyworms (A) defoliate leaves.
- Earworms (B) feed on the developing kernels on the cob.
- Cutworms (D) sever young seedlings at the soil level during the night.
Therefore, only the stem borer is responsible for the dead heart symptom.

Step 3: Final Answer
The maize stem borer (C only) is the insect responsible for the "dead heart" symptom in maize.