The deficiency of boron results in all except

Options

A. top sickness
B. browning of head in cauliflower
C. internal cork of apple
D. marsh spot disease

Answer

To solve the question regarding the deficiency of boron and its effects, we will analyze each option provided in the question step by step.

### Step-by-Step Solution:

1. **Understanding Boron Deficiency**:
- Boron is an essential micronutrient for plants. Its deficiency can lead to various physiological disorders and diseases in plants.

2. **Analyzing the Options**:
- We need to identify which of the listed conditions is **not** caused by boron deficiency.

3. **Option A: Top sickness in tobacco**:
- This condition is indeed associated with boron deficiency. It results in stunted growth and is a recognized symptom of insufficient boron in tobacco plants.

4. **Option B: Browning of head in cauliflower**:
- This is also a symptom of boron deficiency. Cauliflower heads can develop lesions and browning due to lack of boron.

5. **Option C: Internal cork of apple**:
- The internal corking in apples is another condition linked to boron deficiency. It affects the internal structure of the fruit.

6. **Option D: Marasmius disease in pea plants**:
- This disease is not caused by boron deficiency but rather by manganese deficiency. Marasmius disease leads to poor growth and is specifically associated with a lack of manganese.

7. **Conclusion**:
- Since options A, B, and C are all linked to boron deficiency, while option D is not, the correct answer to the question is **D (Marasmius disease in pea plants)**.

### Final Answer:
The deficiency of boron results in all except **D (Marasmius disease in pea plants)**.