Sydney NSW, Australia
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2021-09-17T06:21:00.0000000Z
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TOMATO YELLOW LEAF CURL VIRUS - AUSTRALIA: (VICTORIA)

ProMED

Source: HortiDaily [summ., edited]
https://www.hortidaily.com/article/9355143/tylcv-found-in-northeast-victoria-australia/
The Australian horticultural industry is encouraged to report any _Tomato yellow leaf curl virus_ (TYLCV) symptoms in tomatoes following the detection of the virus in northeastern Victoria. It is reported to cause severe damage to plant leaves resulting in an eventual reduction in crop yield.

Further information on the outbreak from Agriculture Victoria (see link below) states that, in response to the detection of TYLCV, producers of any host plants will be contacted to undertake surveillance over the next 3-6 months. Surveys will occur across the state to investigate potential distribution. Inspections will involve the collection of leaf samples for diagnostic analysis and installation of insect traps. Inspections will start with glasshouse growers and may move to field crops later on.

[Agriculture Victoria additional information:
https://ausveg.com.au/app/uploads/2021/09/TYLCV_September.pdf]
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Communicated by:
ProMED
<promed@promedmail.org>
[_Tomato yellow leaf curl virus_ (TYLCV; genus _Begomovirus_) originates from the Middle East and is one of the most damaging viruses of tomato worldwide. Field cropping of tomatoes has been abandoned in some areas due to TYLCV. The virus belongs to the tomato leaf curl and yellow leaf curl clades of the genus. Known species in these clades cause similar diseases on solanaceous and other crops and are considered to be the biggest constraint to solanaceous and cucurbit crops, both in terms of yield losses (up to 100 percent in tomato) and loss of fruit quality. TYLCV symptoms on tomato may be confused with some nutritional or environmental problems; they include interveinal yellowing and distortion of leaves; stunting and distortion of plants; withering and early abortion of flowers. Any fruits that may still be produced are not fit for consumption.

The virus is transmitted in a persistent manner by the silverleaf whitefly (_Bemisia tabaci_ biotype B). TYLCV can also be transmitted by mechanical inoculation (poorly), plant material (such as infected tomato transplants), and by grafting, but is not transmitted by seed or contact between plants. Tomato cultivars with increased levels of resistance or tolerance are available. Transgenic tomato plants incorporating TYLCV capsid protein genes have been found to be resistant to the virus.

Control of begomoviruses is particularly difficult in open field crops due to the widespread presence and wide host range of the vectors. Whiteflies in themselves are serious pests of many vegetable crops; if virus sources are available locally, high vector numbers are often reflected in high levels of the viral diseases they transmit. Disease management may include pathogen exclusion, vector control, elimination of possible pathogen and/or vector reservoirs, as well as use of resistant crop cultivars, if available.

Novel viruses have been shown to emerge from recombination events during co-infections of some of the viruses in the two leaf curl clades. The new recombinant viruses are often more aggressive and have a widened host range, compared to each of the partners, posing an increased risk to solanaceous and cucurbit crops worldwide.

Maps
Australia (with states):
https://www.nationsonline.org/maps/australia-political-map.jpg and
http://healthmap.org/promed/p/288

Pictures
TYLCV symptoms on tomato:
https://www.lsuagcenter.com/~/media/system/0/e/b/6/0eb68da93be56174506675198505a8b5/tylcv1.jpg,
https://c1.staticflickr.com/9/8057/8226402877_9abf151b5b_b.jpg,
https://www.plantmanagementnetwork.org/pub/php/research/2008/TYLCV/image/TYLCV2.jpg,
https://www.agric.wa.gov.au/sites/gateway/files/TYLCV%203%20bush.jpg, and
https://media.padil.gov.au/Species/136657/3489-large.jpg (affected field)
Photo gallery of symptoms of different begomoviruses:
http://www.forestryimages.org/browse/TaxImages.cfm?fam=651&genus=Begomovirus
Whiteflies:
https://www.planetnatural.com/wp-content/uploads/2012/12/whitefly.jpg and
https://www.pinpointpestcontrol.com/images/whitefly-on-plant.jpg

Links
Information on TYLCV:
https://gd.eppo.int/taxon/TYLCV0,
https://www.cabi.org/isc/datasheet/55402,
https://www.agric.wa.gov.au/plant-biosecurity/tomato-yellow-leaf-curl-virus-declared-pest-0,
https://www2.ipm.ucanr.edu/agriculture/tomato/tomato-yellow-leaf-curl/,
https://www.padil.gov.au/pests-and-diseases/pest/main/136657/3489,
http://www.ipm.ucdavis.edu/PMG/r783103311.html, and
https://doi.org/10.3389/fpls.2018.01198 (germplasm resistance)
Information on leaf curl viral diseases on different hosts:
http://www.oisat.org/pests/diseases/viral/leaf_curl__virus.html and via
https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/tomato-leaf-curl-virus
Virus taxonomy via:
https://talk.ictvonline.org/taxonomy/
Information on whiteflies:
http://www.issg.org/database/species/ecology.asp?fr=1&si=106 and via
https://projects.ncsu.edu/cals/course/ent425/text18/plantvectors.html
- Mod.DHA]


Tomato
Australia
Tomato_yellow_leaf_curl

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