TOMATO SPOTTED WILT VIRUS

In this presentation you will be learning about the SPOTTED WILT VIRUSES which is caused in TOMATO crop. And also its mode of establishment into the crop, deficiency symptoms, life cycle, life span of the virus, yield losses in that particular crop and at last its MANAGEMENT PRACTICES.

1. PAT301. Diseases of field and horticultural crops and their management (1+1) 🍅 Tomato spotted wilt virus

2. INTRODUCTION Tomato spotted wilt virus (TSWV) is a spherical shaped RNA virus. It is one of the 10 most economical destructive plant viruses Also called as Orthotospo virus
The host range of TSWV is Over 1000 species iof 85 families. Common hosts: . Tomatoes, peppers, potatoes, celery, eggplant, peanuts, lettuce, pineapple, cucurbits (melons, squash, cucumbers, etc.), many legumes, many ornamentals, and weeds such as field bindweed and curly dock

3. History This virus disease firstly identified in 1919 at Australia. The disease decreased in prevalence between the 1940s In 1940s to 1980s this disease caused heavy yield loss in tomato at USA and Hawaii.
.The worldwide spread of the western flower thrips ( Frankliniella occidentali s), an efficient TSWVvector, from the westernpart of the USA during the 1980s has certainly played an important role in TSWV emergence.

4. Classification Kingdom - Orthornavirae
Phylum - Negarnaviricota
Class - Ellioviricetes
Order. - Bunyavirales
Familly - Tospoviridae Genus. - Tospovirus

5. Symptoms Stunting is a common symptom of TSWV infection, and is generally more severe when young plants are infected . Chlorotic or necrotic rings form on the leaves of many infected hosts , and may also appear on the fruits of some hosts . Necrosis may develop in the foliage of some hosts,. Although TSWV is not seed transmitted, it may cause discoloration of seed produced on infected hosts . Hence, tomato spotted wilt may affect both the quantity and quality of plant products. Additionally, movement of infected plant material may result in TSWV being introduced into a new setting.

6. Pathogen It is a spherical shaped single stranded RNA virus
Size 80-110 nm In diameter It has 3 RNA’s inside the viral envelope which differ in and size and are called Large, medium, small. Frankliniella occidentalis , the western flower thrips, is considered to be the most important vector species because it is globally distributed and can transmit most tospoviruses

7. Disease Transmission TSWV is transmitted from infected plants to healthy plants by at least ten species of thrips. Thrips are tiny winged insects that feed on plants through sucking mouthparts. Thrips transmit the virus in a persistent propagative manner, which means that once the insect has picked up the virus, the virus replicates within the insect and the insect is able to transmit the virus for the remainder of its life.

8. Challenges in controlling Tospo virus diseases Broad host range Multiple vector species Evolution of new strains
Ability to overcome host plant resistance

9. Disease Management Controlling this disease is difficult. The wide host range, which includes many perennial ornamentals and weeds, enables the virus to successfully overseason from one crop to the next.   Controlling thrips is somewhat more effective in greenhouse situations. In greenhouses, however, growers should take care to avoid repeated sprays of similar insecticides because thrips are able to build up resistance to commonly used insecticides in a relatively short time.

10. Cultural practices Virus free planting material Remove all infected plants. Insect control by traps
Crop rotation Use mulching practices Check seed sources for new cultivars

11. Chemical practices Control of thrips may be obtained with pyrethroids, carbamates, chlorinated hydrocarbons, organophosphates, and soaps. Insecticides are most effective when applied in the morning, when the thrips are most active and the chance for plant damage is reduced.