Tomato spotted wilt virus

Tomato spotted wilt virus (TSWV) causes serious diseases of many economically important plants representing 35 plant families, including dicots and monocots. This wide host range of ornamentals, vegetables, and field crops is unique among plant-infecting viruses. Another unique feature is that TSWV is the only virus transmitted in a persistent manner by certain thrips species. At least six strains of TSWV have been reported; the symptoms produced and the range of plants infected vary among strains Although previously a threat only to crops produced in tropical and subtropical regions, today the disease occurs worldwide. Largely because of wider distribution of the western flower thrips and movement of virus-infected plant material.

Symptoms
Symptoms vary depending on host, but may include:

Tomato
Symptoms expressed on leaves, petioles, stems, and fruit will vary, depending on the stage plants are infected. Young leaves may show small, dark-brown spots and eventually die. Dark brown streaks also appear on stems and leaf petioles. Growing tips are usually severely affected with complete cell death and greatly stunted growth. The plant may exhibit one-sided growth. Tomato fruit set on severely infected plants will display very characteristic symptoms: immature fruit have mottled, light green rings with raised centers.

Pepper
The virus may cause sudden yellowing and browning of young leaves which later die. Long streaks of dead cells appear on stems extending to the growing tips. Fruit formed after infection display large streaks of dead cells and spots while younger fruit may die completely.

Potato
Broad dark spots and necrotic ringspots, often with chlorotic halos, occur on both the lower and upper leaves of affected plants.

Treatment
None. Destroy infected plants. Sterilise soil and equipment.

Prevention
Use techniques to reduce the spread of TSWV by reducing unnecessary contact with plants. Reduce the movement and number of thrips by netting plants, netting points of entry to greenhouses and using yellow sticky cards to monitor thrips levels.

Hosts
Potential hosts of TSMV include:


 * Aubergine
 * Bean
 * Cauliflower
 * Celery
 * Cowpea
 * Cucumber
 * Endive
 * Lettuce
 * Peanut
 * Pepper
 * Potato
 * Spinach
 * Tobacco
 * Tomato