Bt cotton is a genetically modified organism (GMO) or genetically modified pest resistant plant cotton variety, which produces an insecticide to combat bollworm.



Bt cotton is an insect-resistant transgenic crop designed to combat the bollworm. Bt cotton was created by genetically altering the cotton genome to express a microbial protein from the bacterium Bacillus thuringiensis

Introduction:
Biological control is a method used to control pests and diseases by utilizing living organisms such as microbes. These organisms can be beneficial in reducing the population of harmful pests or pathogens, thereby protecting crops and increasing agricultural yields. Among the given options, the example of carrying out biological control of pests/diseases using microbes is:

Option 3: Trichoderma sp. against certain plant pathogens

Explanation:
Trichoderma is a genus of fungi that are commonly used as biological control agents in agriculture. They have the ability to suppress the growth of plant pathogens and promote plant growth. Trichoderma species are known for their antagonistic activity against various fungal pathogens such as Fusarium, Rhizoctonia, and Pythium.

Benefits of Trichoderma in biological control:
1. Antagonistic activity: Trichoderma species produce enzymes and secondary metabolites that inhibit the growth of plant pathogens. They compete for nutrients and space with the pathogens, thereby reducing their population.
2. Induced systemic resistance: Trichoderma can induce the plant's defense mechanisms, making it more resistant to diseases caused by pathogens. This helps in preventing the spread and severity of diseases.
3. Nutrient solubilization: Trichoderma can solubilize nutrients, making them available to plants. This enhances plant growth and vigor, reducing their susceptibility to diseases.
4. Environmental sustainability: The use of Trichoderma as a biological control agent is environmentally friendly, as it reduces the reliance on chemical pesticides that can have negative impacts on ecosystems.

Application of Trichoderma in disease control:
Trichoderma is commonly applied as a biocontrol agent in the form of a bio-fungicide, either as a seed treatment or as a soil amendment. The spores or mycelium of Trichoderma are introduced into the agricultural system, where they colonize plant roots and the surrounding soil. This colonization helps in suppressing the growth of pathogens and protecting the plants from diseases.

Conclusion:
The use of Trichoderma species as a biological control agent against certain plant pathogens is an effective and sustainable approach in pest and disease management. It offers several benefits, including antagonistic activity, induced systemic resistance, nutrient solubilization, and environmental sustainability. Incorporating Trichoderma into agricultural practices can contribute to healthier crops, increased yields, and reduced reliance on chemical pesticides.