Potato mop-top virus (PMTV) is a plant virus that primarily affects potatoes, causing tuber quality issues and economic losses. Here’s some information on its symptoms, recommendations, causes, and preventive measures:

Symptoms:

1. Tuber Symptoms: The most characteristic symptom of PMTV is the development of corky rings or necrotic lesions on the surface of potato tubers, often referred to as “mop-top” symptoms.
2. Internal Necrosis: In severe cases, internal necrotic lesions can also develop within the tubers, affecting their quality and marketability.
3. Foliage Symptoms: Infected plants may exhibit mild to moderate leaf curling and yellowing, but foliage symptoms are usually not as prominent as tuber symptoms.
4. Reduced Yield: Severe PMTV infections can lead to reduced yields due to poor tuber quality and plant vigor.

Recommendations:

1. Use Certified Seed Potatoes: Plant certified disease-free seed potatoes obtained from reputable sources to minimize the risk of introducing PMTV into fields.
2. Crop Rotation: Rotate potato crops with non-host crops to reduce the buildup of PMTV inoculum in the soil.
3. Sanitation: Practice good sanitation measures to prevent the spread of PMTV, including cleaning and disinfecting equipment, and removing and destroying infected plant material.
4. Vector Control: Manage soil-borne vector populations, such as the powdery scab fungus (Spongospora subterranea), which can transmit PMTV to potatoes.
5. Resistant Varieties: Plant potato varieties that are resistant or tolerant to PMTV, where available.

Causes:

1. Soil-Borne Vector Transmission: PMTV is primarily transmitted to potatoes through the soil-borne vector, the powdery scab fungus. The fungus can harbor the virus and infect potatoes during tuber formation.
2. Contaminated Plant Material: Using infected seed potatoes for planting can introduce PMTV into new fields.
3. Environmental Persistence: PMTV can persist in soil and infect subsequent potato crops if proper management practices are not followed.

Preventive Measures:

1. Vector Management: Implement measures to manage powdery scab fungus populations, such as maintaining optimal soil pH and fertility levels and using resistant potato varieties.
2. Sanitation Protocols: Ensure proper sanitation practices are followed, including cleaning and disinfecting equipment and machinery between fields and seasons.
3. Crop Monitoring: Regularly monitor potato crops for symptoms of PMTV and take appropriate action if detected.
4. Certified Seed Potatoes: Source seed potatoes from certified disease-free sources to reduce the risk of introducing PMTV into fields.
5. Soil Management: Implement soil management practices that promote healthy soil conditions and reduce the survival and spread of PMTV and its vector.

By implementing these recommendations and preventive measures, potato growers can help minimize the impact of Potato Mop-Top Virus on their crops and reduce the risk of virus transmission within their fields, thereby preserving tuber quality and maximizing yields.