Tomato yellow leaf curl bigeminivirus (TYLCV)
English names: Tomato yellow leaf curl virus
Nordic names: Tomaatin keltakäppyrälehtivirus (FI)
Major host plants
The main host of TYLCV is tomatoes (Solanum lycopersicum). Ornamentals such as Eustoma grandiflorum can be severely damaged by natural infection. The plants which can be infected by the virus include 15 species in five different families.
Tomato plants infected at an early stage are stunted; their terminal and axillary shoots erect while leaflets are reduced in size and appear abnormal in shape. Foliar symptoms are the most diagnostic for this disease. Soon after infection, new leaves are cupped downward, whereas leaves developing later are chlorotic, deformed, and rolled upwards. Plants lose vigour and stop producing marketable fruits. If infection takes place at a later stage of growth, the fruits already present develop normally.
TYLCV was first described in the Middle East in the 1960s, and it started to spread when biotype B of its vector, the cotton whitefly Bemisia tabaci, started to spread through the EPPO region. The vector is now very widely distributed throughout the world.
A map can be downloaded from EPPO’s website. See instructions here.
It is usually the biotype B of Bemisia tabaci that acquires the virus by feeding on infected plants for 10–30 minutes and transmit the virus to healthy plants after 20–24 hours. At least 15 minutes of feeding on the new host is required for transmitting the virus. TYLCV can persist in the vector for 10–12 days, but it does not multiply within the whitefly, and it is not passed from one generation to the next. However, whitefly nymphs feeding on infected plants can acquire the virus and transmit it when they reach the adult stage. Symptoms appear 15 days after inoculation.
The primary way the virus is spread over short distances is by its vector, the whitefly Bemisia tabaci. Over long distances, the virus is spread through the movement of infected plants, especially tomato transplants. The virus is not seed-transmitted nor spread mechanically (e.g. by touch).
Detection and inspection
The disease is difficult to identify due to the great variation in symptoms. Accurate laboratory tests should be used to identify the virus as the symptoms alone cannot be used for definitive identification.
Pest status and importance
Whenever TYLCV is introduced into a new country where the vector is already present, it rapidly spreads throughout commercial tomato crops causing substantial losses.
Source of information
See further information here:
Author: Christiane Scheel and Elise T. Yamamoto Buch
Editor: Dorthe Vestergaard