Question

Statement A: 2,4-D should be applied in grain Sorghum when it attains a height of 10-30 cm.
Statement B: 2,4-D should be applied in wheat 18-25 days after sowing

• A. Both A and B are true.
• B. Both A and B are false.
• C. A is true but B is false.
• D. B is true but A is false.

Hint:

Remember the critical stages:
- Wheat 2,4-D timing: 30-35 DAS (tillering). Never apply at CRI stage (18-25 DAS) to avoid crop injury.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
2,4-D is a selective, systemic herbicide used to control broadleaf weeds.
Its application timing is critical; applying it too early or too late can cause severe phytotoxic damage to the crop.

Step 3: Detailed Explanation:
1. Statement A: In grain Sorghum, 2,4-D must be applied only when the crop is active and has attained a height of 10 to 30 cm (typically 4-leaf to 8-leaf stage).
If applied earlier (less than 10 cm) or later (during booting), it damages the root system or causes spike/stalk malformation. Thus, Statement A is true.
2. Statement B: In wheat, 2,4-D should be applied 30 to 35 days after sowing (DAS) during the active tillering stage.
Applying it too early (18-25 DAS, during the Crown Root Initiation stage) causes severe crop damage, leading to malformed leaves ("onion leaf") and distorted ear heads. Thus, Statement B is false.

Step 4: Final Answer:
The correct option is 3, which corresponds to A is true but B is false.