Which of the following is not correctly matched

Options

A. Root knot disease – Meloidogyne javanica
B. Smut of bajra – Tolysporium penicillariae
C. Covered smut of barley – Ustilago nuda
D. Late blight of potato – Phytophthora infestans

Explanation

To determine which of the following is not correctly matched, we will analyze each disease and its corresponding pathogen.

1. **Root Knot Disease**: This disease is caused by *Meloidogyne* (a genus of plant-parasitic nematodes). This match is correct.

2. **Smut of Bajra**: This disease is caused by *Ustilago* (a genus of fungi). This match is also correct.

3. **Covered Smut of Barley**: This disease is caused by *Ustilago nuda*. However, in the transcript, it incorrectly states that it is caused by *Ustilago* (without specifying the species). This match is incorrect.

4. **Late Blight of Potato**: This disease is caused by *Phytophthora infestans*. This match is correct.

Now, summarizing the findings:
- Root Knot Disease - Correct
- Smut of Bajra - Correct
- Covered Smut of Barley - Incorrect (should be *Ustilago nuda*)
- Late Blight of Potato - Correct

Thus, the disease that is not correctly matched is **Covered Smut of Barley**.

### Step-by-Step Solution:
1. Identify the diseases listed in the question.
2. Research or recall the pathogens responsible for each disease.
3. Compare the pathogens with the ones provided in the question.
4. Identify any discrepancies in the matches.
5. Conclude which disease is not correctly matched based on the analysis.