Tomato yellow leaf curl virus

Tomato yellow leaf curl virus (TYLCV) can infect over 30 different kinds of plants, but it is mainly known to cause devastating losses of up to 100 per cent in the yield of tomatoes. Both field and glasshouse grown tomatoes are susceptible. TYLCV is vectored by silverleaf whitefly (Bemisia tabaci). Following recent detections, silverleaf whitefly is now considered established in Victoria.

TYLCV is a begomovirus, implying it has a wide host range on dicotyledons. There are two strains of TYLCV, a mild strain and a severe strain. The mild strain was considered responsible for the recent detection of TYLCV in tomato and weed plants in northern Victoria (David Lovelock pers. comm). The severe strain infects bean and tomato.

Symptoms of TYLCV

The most obvious symptoms in tomato plants are small leaves that become yellow between the veins. The leaves also curl upwards and towards the middle of the leaf (Figure 1).

In seedlings, the shoots become shortened and give the young plants a bushy appearance. In mature plants only new growths produced after infection is reduced in size. Although tomato production is reduced by the infection, the fruit appears unaffected.

Spread of TYLCV

TYLCV is transmitted from diseased to healthy plants by silverleaf whitefly, which feeds on a wide range of hosts (Figure 2). Levels of TYLCV can be correlated to the population size of its vector silverleaf whitefly. It is not known if native whiteflies can spread the virus.

The TYLCV strain occurring in Australia is not known to be seed transmitted or to be transmitted mechanically.

Hosts of TYLCV

TYLCV mainly infects tomatoes but has also been reported on glasshouse grown Capsicums. Bean (Phaseolus vulgaris) (Figure 3), petunia (Petunia x hybrida), and lisanthus (Eustoma grandiflorum) show severe symptoms.

Weeds such as thorn apples (Datura stramonium)  can show symptoms, others such as Marsh mellow (Malva parviflora)  are symptomless carriers, while cotton and aubergine, are immune to the virus.

List of common hosts of TYLCV (Walker 2006)

• Erect tar vine or erect spider vine (Boerhavia erecta)
• Capsicum or chilli pepper (Capsicum annuum and Capsicum chinense)
• Tick weed (Cleome viscose)
• Lobed croton (Croton lobatus)
• Cyanchum acutum (common name unknown)
• Common thorn apple (Datura stramonium)
• Euphorbia spp.
• Lisianthus (Eustoma grandiflora)
• Tomato (Lycopersicon esculentum)
• Macroptilium spp.
• Small-flowered mallow (Malva parviflora and other Malva spp.)
• Mercurialis ambigua (common name unknown)
• Beans (Phaseolus vulgaris)
• Physalis spp.
• Knot weed or wire weed (Polygonum spp.)
• Sida spp.
• Blackberry nightshade (Solanum nigrum)
• Hairy nightshade (Solanum luteum or Solanum villosum)
• Wissadula spp.
•  

TYLCV symptoms on bean

TYLCV (severe strain) infection on bean leaves has symptoms of yellow mosaic, crumpled, thickened and curled upwards or downwards leaflets (Figure 3). Apical and side shoots show abnormal growth (Figure 3). Fruit production is severely limited under glasshouse conditions.

Younger plants seem to be more susceptible to TYLCV or perhaps more attractive to the vector and hence the disease is more severe on plant infected at this stage. When grown together, tomato plants seem to be more susceptible than bean plants to TYLCV (Papayiannis et al 2007).

Epidemiology of TYLCV

TYLCV infected plants tend to be found randomly or in patches in a crop.

Overseas, all greenhouses infested with high populations of silverleaf whitefly have tomatoes infected with TYLCV. Autumn grown crops were the worst infected with TYLCV and crop losses were described as ‘drastically reduced’.

Distribution of TYLCV

TYLCV originated in the eastern Mediterranean in the 1960’s and spread worldwide, becoming a serious problem for tomato production.

The world-wide spread of TYLCV is suspected to be associated with the movement of commercial tomato and ornamental plants contaminated with virus infected whitefly.

It was eradicated from the Netherlands in 2008.

TYLCV was first detected in Australia in early 2006 in Brisbane on cherry tomatoes and in Bundaberg in both commercial and home garden tomatoes. TYLCV is also present in the Northern Territory.

Distinguishing TYLCV from other conditions

TYLCV can be confused with other diseases and disorders.

List of disease and disorder symptoms similar to TYLCV (Walker 2006)

References

Czosnek H, 2020. Tomato yellow leaf curl virus (leaf curl). Crop Protection Compendium. Wallingford, UK: CABI. DOI:10.1079/CPC.55402.20210104831

Navas-Castillo J, Sanchez-Campos S, Diaz JA, 1999. Tomato yellow leaf curl virus causes a novel disease of common bean and severe epidemics in tomato in Spain. Plant Disease, 83:29-32.

Papayiannis, LC, Paraskevopoulos, A, Katis, NI, 2007. First report of Tomato yellow leaf curl virus infecting common bean (Phaseolus vulgaris) in Greece. Plant Disease, 91(4), 465. doi: 10.1094/PDIS-91-4-0465C

Walker K, 2006 Tomato yellow leaf curl virus (TYLCV) (Tomato yellow leaf curl virus (TYLCV) Begomovirus)

Photo credits

Figure 1 John Thomas, Queensland Department of Industries and Fisheries

Figure 2 W. Billen, Pflanzenbeschaustelle, Weil am Rhein, Bugwood.org

Figure 3 Navas Castillo et al.