Symptoms
- Leaves are mottled and streaked with white
- Dead spots or patches on the leaves
- Colourless veins (see right)
- Translucent patches on the leaves
- Stunted plants
- Malformed outgrowths of the leaves
- White streaks on the flower petals
Warning:
Some of these symptoms can be confused with nutrient deficiencies.
However, sweet peas are unlikely to show such symptoms if
the precaution is taken to supply good quality balanced fertiliser
before planting.
Other crops affected
Broad beans, peas, clover and other legume plants. Some viruses also affect lettuce, daisy-flowered plants and other members of the Compositae.
Cause
There are at least 11 viruses that affect sweet peas in the UK. The most important are spread by aphids which feed on the sap of infected plants and carry the infection to other plants on their mouthparts. Different viruses cause different symptoms and more than one virus may be present in a plant. Affected plants lose vigour and in extreme cases the plants may die.
Non-chemical control
- Eliminate legume weeds such as clover, which may provide natural reservoirs of disease.
- Avoid growing other vulnerable plants nearby.
- Use virus-free seed.
- Remove and destroy affected plants as soon as seen.
- Control aphids
Chemical control
There are no chemicals available that will kill viruses. None of the insecticides currently available to home gardeners are likely to give sufficient control of aphids to prevent virus infection.