Gray speck of oats and marsh spots of peas are caused by:

Options

A. Deficiency of Mn
B. Deficiency of Mn and Mo respectively
C. Deficiency of Mo and Mn respectively
D. Excess of Mo

Answer

**Step-by-Step Solution:**

1. **Identify the Diseases:**
- The question mentions two specific diseases: Gray speck of oats and Marsh spots of peas.

2. **Understand the Cause of Gray Speck:**
- Gray speck of oats is associated with a deficiency of manganese. Manganese is a micronutrient essential for plant growth, particularly in leaves and seeds.

3. **Symptoms of Manganese Deficiency:**
- When there is a deficiency of manganese in oats, the following symptoms can occur:
- Development of gray spots on the leaves (Gray speck).
- Poor development of the root system.
- Intervenal chlorosis, where the veins of the leaves remain green while the areas between them turn yellow.

4. **Understand the Cause of Marsh Spots:**
- Marsh spots in peas are also caused by a deficiency of manganese.

5. **Symptoms of Marsh Spots:**
- In the case of marsh spots, the symptoms include:
- Brown spots in the center of the leaves.

6. **Conclusion:**
- Both gray speck of oats and marsh spots of peas are caused by a deficiency of manganese. Therefore, the correct answer to the question is that these diseases are caused by the deficiency of manganese.

**Final Answer:**
- The gray speck of oats and marsh spots of peas are caused by the deficiency of manganese.

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