Tomato Spotted Wilt Virus
Class: Viruses
Common Name
Tomato Spotted Wilt Virus
Scientific name
Tomato Spotted Wilt Virus
Potential Hosts
Tobacco, peanut, tomato, pepper, potato, eggplant, lettuce, endive, celery, bean, cowpea, spinach, cucumber, cauliflower, and many more
Who am I?
Tomato spotted wilt virus (TSWV) is from the tospoviruses genus and is common worldwide due to the spread of its main vector, the western flower thrips. The infection results in spotting and wilting of the infected crop, reduced yield, and in a later stage it will lead to death of the plant. Early symptoms show on the stems and leaves, while symptoms upon fruits appear at a later stage. Foliage and stems: appearance of circular stains of about 5.0 cm in diameter and quickly become necrosis. Fruits: round halo-like and sometimes spiral spots. When plant is fully infected then the leaves have all over chlorosis with formations of necrotic spots and delayed development.
The virus is transmitted by thrips (mainly the western flowers thrips), and it is not seedborne. There are a large number of hosts, such as weeds, that allow the virus to remain present even after the contaminated crop was harvested. This can cause the weeds to contaminate crops the following season and makes disease control difficult.
Control measures
There are no treatment for viruses. Infected plants with tomato spotted wilt virus should be removed from the field and destroyed as soon as possible. Since the virus might have already spread before the symptoms appeared, focus should be on prevention and usage of resistant varieties.
Prevention of infection should focus on eliminating thrips, which can be difficult. Thrips can only be infected in the larval phase when there is contact with an infected plant. Infected thrips that have matured can transmit the virus by flying and landing on healthy plants.
Cultural
Grow Inside Structures: keep the structure closed and the nets free of holes.
Get rid of weeds, use pests monitoring techniques and traps, and cover the ground with a reflective black-silver cover.
Conventional (chemical)
It’s hard to manage thrips effectively with insecticides. They have high maneuverability skills and their egg and pupa stages are protected. Another common issue that reduces effectiveness of treatments is inadequate coverage when spraying insecticides as it difficult to spray all the areas.
Try to avoid using organophosphate, carbamates, or pyrethroids insecticides; they will effectively eliminate natural enemies and pollinators, while leaving most of the thrips population intact and unharmed.
Organic
Spinosad-based products are not cheap, but possibly the best insecticides available today to combat thrips. Spinosad-based insecticides are fermented products of a naturally occurring bacterium and certain formulations are organically acceptable. Keep in mind that combining horticultural oil with each spray application is essential and will increase overall effectiveness.
Biological
A successful commercially available natural enemies of thrips are of the genus Orius (“minute pirate bug”), omnivorous bugs in the Anthocoridae family.
Caution and careful notice should be taken when using any plant protection products (insecticides, fungicides, and herbicides). It is the grower’s sole responsibility to keep track of the legal uses and permissions with respect to the laws in their country and destination markets. Always read the instructions written on labels, and in a case of contradiction, work in accordance to the product label. Keep in mind that information written on the label usually applies to local markets. Pest control products intended for organic farming are generally considered to be less effective in comparison to conventional products. When dealing with organic, biologic, and to some extent a small number of conventional chemical products, a complete eradication of a pest or disease will often require several iterations of a specific treatment or combination of treatments.