The first bioherbicide developed in 1981 was based on

Options

A. Phytophthora palmivora
B. Phytophthora infestans
C. Bacillus thuringiensis
D. Azadirachta indica

Explanation

To solve the question regarding the first bioherbicide developed in 1981, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Concept of Bioherbicides**:
- Bioherbicides are biological agents used to control weeds. They can be derived from natural organisms, such as fungi, bacteria, or other plants.

2. **Identify the Year and Context**:
- The question specifies the year 1981, which is crucial for identifying the correct bioherbicide.

3. **Research the Specific Bioherbicide Developed in 1981**:
- The first bioherbicide developed in 1981 was based on a specific organism. In this case, it was based on the pathogen *Phytophthora palmivora*.

4. **Understand the Role of *Phytophthora palmivora***:
- *Phytophthora palmivora* is a fungus-like organism that is known to cause diseases in plants, particularly bud rot and root rot. It is classified as a mycoherbicide.

5. **Identify the Target Weed**:
- This bioherbicide was specifically used to control *Mimosa pudica* (also referred to as *Maurinia odorata* in some contexts), which is a weed that can be problematic in certain agricultural settings.

6. **Conclude the Answer**:
- Based on the above information, we can conclude that the first bioherbicide developed in 1981 was based on *Phytophthora palmivora*.

### Final Answer:
The first bioherbicide developed in 1981 was based on *Phytophthora palmivora*.

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