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Tomato leaf curl New Delhi virus on zucchini in Almeria, Spain

A ProMED-mail post <http://www.promedmail.org>
ProMED-mail is a program of the International Society for Infectious Diseases <http://www.isid.org>

Date: Mon 13 Nov 2017
Source: HortiDaily [edited]
<http://www.hortidaily.com/article/39132/Spain-New-Delhi-virus-reduces-and-delays-courgette-production>

The courgette [zucchini] season is developing in Almeria [Andalusia] with a lower production that was marked by the impact of the New Delhi virus. "The New Delhi virus has caused a delay in the harvest [and] is limiting the courgette production. This year [2017], there will be a lower production compared to previous years," says the Almeria-based company Escobi [which] handles a volume of around 20 million kilos [about 44 million lb] of courgettes. The demand for courgettes is on the rise.

Communicated by: ProMED-mail <promed@promedmail.org>

[_Tomato leaf curl New Delhi virus_ (ToLCNDV; genus _Begomovirus_) has been reported to cause severe yield losses on tomato and watermelon crops on the Indian subcontinent. It 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 can lead to considerable yield losses. Begomoviruses are transmitted by different whitefly vectors (such as _Bemisia tabaci_ biotypes), and many can also be transmitted by mechanical means and grafting, but they are not seed transmitted.

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.

Begomovirus control is particularly difficult in open field crops due to the widespread presence and wide host range of whiteflies. Disease management may include pathogen exclusion, vector control, as well as elimination of possible pathogen and/or vector reservoir plants. In some cases, crop cultivars with increased virus resistance are available.

ToLCNDV was limited to Asia until it was reported from Europe for the 1st time in 2013 on cucurbits in Spain (ProMED-mail post http://promedmail.org/post/20131223.2131729). It has since also been reported from Italy (ProMED-mail post

http://promedmail.org/post/20160327.4121164) and Tunisia and was included in the EPPO alert list. ToLCNDV has a wider host range than the related _Tomato yellow leaf curl virus_, which had previously been present in the region.

The source of the Mediterranean incursion so far remains unknown.

Recent research (see link below) has shown that a novel recombinant strain causes the severe damage to cucurbit crops in the region, but poorly infects tomatoes. In Spain, a genetically uniform virus population was identified which would be compatible with a recent introduction. Major concerns in the region are a continued spread, both geographically and in host range, and the potential of coinfections with other begomoviruses already present which may lead to synergistic enhancement of symptoms as well as emergence of further strains due to additional recombination events.

Maps

Spain:

<https://www.ezilon.com/maps/images/europe/political-map-of-Spain.gif>

and

<http://healthmap.org/promed/p/6672>

Provinces of Spain:

<http://www.venamicasa.com/wp-content/uploads/2012/03/spain_map3.gif>

Pictures

ToLCNDV symptoms:

<http://cienciacebas.files.wordpress.com/2013/09/aranda-1.jpg>

(zucchini) and

<http://cienciacebas.files.wordpress.com/2013/09/aranda-2.jpg>