Question

The Tristeza disease in citrus is caused by-

• A. Bacteria
• B. Fungus
• C. Virus
• D. Mycoplasma

Hint:

Tristeza = Citrus tristeza virus (CTV). Spread by aphids, causes decline in citrus rootstocks.

Answer 1

The Correct Option is C

Step 1: Identify the disease.
Tristeza disease is one of the most destructive diseases of citrus worldwide. The word "Tristeza" means sadness in Spanish, referring to the decline of infected citrus trees.
Step 2: Causal organism.
The causal agent is Citrus tristeza virus (CTV), which belongs to the genus Closterovirus. It is a phloem-limited virus transmitted by aphids, mainly Toxoptera citricida.
Step 3: Checking the options.
- Bacteria: Wrong, citrus canker is bacterial, not tristeza.
- Fungus: Wrong, tristeza is not caused by fungi.
- Virus: Correct, Citrus tristeza virus is responsible.
- Mycoplasma: Wrong, phytoplasmas cause diseases like little leaf, not tristeza.
Step 4: Conclusion.
Hence, Tristeza disease in citrus is caused by a virus.