Potato
Potato Mop-Top Virus
PMTV
Virus
5 mins to read
In a Nutshell
- Bright yellow blotches and ring patterns on lower or middle leaves.
- Mosaic patterns on upper leaves.
Can also be found in
Potato
Symptoms
On stems, characteristic patterns develop with bright yellow blotches and ring or line patterns on lower or middle leaves. A less common symptom is the existence of pale, V-shaped chlorotic pattern on the leaflets of young upper leaves resulting in distinct mosaic. Mop-top causes an extreme shortening of internodes accompanied by crowding or bunching of foliage. Some smaller leaves may have wavy or rolled margins resulting in dwarfed and bunched growth. Concentric rings of 1 - 5 cm diameter are present on the surface of the tubers. Tubers may also develop brown necrotic lines, arcs and rings in the flesh.
Recommendations
Organic Control
Monitor the presence of the virus by isolating the virus using soil and bait plant methods and practise early detection through the use of indicator plants. Plant potato cultivars that do not express tuber necrosis symptoms.
Chemical Control
Always consider an integrated approach with preventive measures and available biological treatments. There is no effective, environmentally safe chemical control of the disease and the best method to prevent the spread of the disease is to plant virus-free tubers on PMTV free land.
What caused it?
The damage is caused by the potato mop-top virus (PMTV), which survives in the soil within dormant resting spores of its fungal vector. Powdery scab fungus (Spongospora subterranea) is a soil-borne organism and is the only known vector of the virus. The virus can also be transmitted secondarily through activities resulting in the movement of soil and tubers may also become contaminated during storage and grading through dust originating from a contaminated seed lot. The virus and its vectors are found in cool and humid climates. The presence of this disease can result in substantial yield losses in sensitive cultivars due to decreased tuber production and quality.
Preventive Measures
- Plant virus-free tubers on virus-free soils.
- Monitor fields regularly for the presence of the virus.
- Maintain sanitary practices on the fields.
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