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Date: January 21, 2008
Source: Peppers Today [edited]
<http://www.pepperstoday.com/new.php?news_id=580>

Tomato spotted wilt virus threatens pepper recovery

The continued appearance of plants affected by tomato spotted wilt virus
(TSWV) in pepper [capsicum] crops since mid-December [2007] is making life very difficult for pepper growers in Almeria. Despite the overall success of the Almerian pepper campaign, as reported by the sector in early December [2007], there has been evidence this January [2008] of some significant losses, mainly in the latest crops transplanted at the end of July and August. With respect to the latest plantings in August, barely 10-15 per cent of the anticipated production volume has been harvested to date. Nor is the current price situation in mid-January offering growers much encouragement to continue with this crop.

According to Mr Pedro Pleguezuelo, product manager at Syngenta in Spain, the incidence of TSWV could also have an influence on how the pepper crop area develops in the next campaign: "Pepper growers in Almeria are considering the possibility of reducing the area assigned to this vegetable, mainly due to the risk of a high incidence of TSWV."

There has been a redistribution of the pepper plantation area in Almeria in the current campaign, with some farmers opting for other crops. This shows that some pepper producers foresaw certain difficulties of adaptation in the first campaign that employed integrated crop management. "However, it is clear that everyone believes that integrated crop management is the best and the safest technique for ensuring the highest fruit quality, and improvements will be seen in forthcoming campaigns," Pleguezuelo told Peppers Today.

The key vegetables which have gained hectares at the expense of peppers have been courgettes [zucchini], with a 15 per cent larger plantation area, cucumbers (> 8-9 per cent) and tomatoes (> 3-4 per cent). Areas growing aubergines and other types of cucumber have also shown an increase.

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

[Tomato spotted wilt virus (TSWV; type species of genus _Tospovirus_) has one of the broadest host ranges among plant viruses and is one of few affecting both dicot and monocot hosts. It is regarded as one of the most economically destructive plant pathogens and has had a serious impact on many crop species worldwide causing up to 100 per cent yield loss in some instances. Diseases attributed to TSWV were 1st reported in Australia about 1915. TSWV (and some other tospoviruses) constitute a severe threat to the cultivation of solanaceous, leguminous and cucurbit vegetables worldwide.
On capsicum and tomato, it affects both shoots and fruit causing leaf distortion, spotting, wilting and necrotic streaks as well as distortion, discolouration and ring patterns on fruit. Early symptoms are often difficult to diagnose.

TSWV is transmitted by various species of thrips, including the western flower thrips (_Frankliniella occidentalis_), the onion thrips (_Thrips tabaci_), and the chilli thrips (_Scirtothrips dorsalis_). Thrips are plant pests in their own right causing considerable leaf damage. The virus needs to be acquired during the nymph stage by feeding on infected plants, and insects retain the ability to transmit it for the remainder of their lives.
TSWV multiplies in the vector but cannot be passed on from infected females through the eggs. It is not seed transmitted but transmission by mechanical means and grafting has been reported. Weed species can serve as pathogen reservoirs. Disease management includes vector control, use of clean planting material, control of weed hosts of virus and vectors, and phytosanitary measures.

TSWV has been included on the quarantine list of the European Plant Protection Organisation (EPPO). So far the only efficient method to control TSWV in pepper and tomato crops in the Mediterranean region has relied on host resistance genes. However, resistance breaking strains of TSWV on capsicum and tomato cultivars have been reported in recent years both under experimental conditions and in the field. All the alternative crops suggested in the above report are also hosts of TSWV and its thrips vectors, and crossing over of TSWV between these hosts can occur. A mere change of host crop species is therefore not likely to eliminate the virus problem in the region.

Maps
Spain:
<http://www.map-of-spain.co.uk/large-map-of-spain.htm>  and <http://healthmap.org/promed?v=40.2,-3.6,5>
Provinces of Spain:
<http://www.data-spain.com/map.html>
Almeria:
<http://www.sun-homes.co.uk/images/maps/almeria_detailed_map.jpg>
Worldwide distribution of TSWV (September 2006):
<http://www.eppo.org/QUARANTINE/virus/Tomato_spotted_wilt_virus/TSWV00_map.htm> 

Pictures
TSWV symptoms on capsicum:
<http://vegetablemdonline.ppath.cornell.edu/PhotoPages/Tomatoes/Tom_SpWilt/Tom_SpWiltFS14.htm> 

TSWV symptoms on tomato:
<http://www.ag.auburn.edu/aaes/organicveg/images/clip_image002_000.jpg>  and <http://www.ces.ncsu.edu/copubs/ag/fnv/veg/005/spottedwilt.gif>
TSWV on a range of hosts (including _Capsicum_ spp.), picture galleries:
<http://www.eppo.org/QUARANTINE/virus/Tomato_spotted_wilt_virus/TSWV00_images.htm>
and
<http://vegetablemdonline.ppath.cornell.edu/PhotoPages/Tomatoes/Tom_SpWilt/Tom_SpWiltPhotoList.htm> 

Western flower thrips:
<http://www.insectimages.org/images/768x512/4387048.jpg>
Onion thrips:
<http://www.insectimages.org/images/768x512/1327078.jpg>
Chilli thrips:
<http://www.insectimages.org/images/768x512/5207031.jpg>
Links
TSWV information:
<http://www.oznet.ksu.edu/dp_hfrr/extensn/problems/tomswv.htm>,
<http://www.ipm.ucdavis.edu/PMG/r783102211.html>,
<http://www.defra.gov.uk/planth/pestnote/tswv.htm>  and <http://www.apsnet.org/online/feature/tospovirus/>
TSWV fact sheet:
<http://vegetablemdonline.ppath.cornell.edu/factsheets/Virus_SpottedWilt.htm>
Break-down of TSWV resistance in pepper and tomato:
<http://www.bspp.org.uk/ndr/july2004/2004-34.asp>  and <http://www.bspp.org.uk/ndr/jan2005/2005-08.asp>
TSWV taxonomy:
<http://phene.cpmc.columbia.edu/ICTVdB/11005003.htm>
Description of western flower thrips vector:
<http://www.gladescropcare.com/wfthp.html>
Thrips information:
<http://www.cals.ncsu.edu/course/ent425/text18/plantvectors.html>
EPPO quarantine alert list:
<http://www.eppo.org/QUARANTINE/listA2.htm>  - Mod.DHA]

[see also in the archive:
2007
---
Tomato viruses TSWV, TICV - Jordan: 1st reports 20071223.4123 Tomato spotted wilt virus, tomato - USA (CA) 20070608.1872
2005
---
Tomato viruses - Ecuador 20051125.3418
Tomato spotted wilt, Sw5 resistance gene - Italy 20050329.0914
2004
---
Tomato spotted wilt, Iris yellow spot, onion - USA (GA) 20041031.2938 Tomato spotted wilt, pepper - Spain 20040605.1519
2003
---
Tomato spotted wilt, tomato - USA (FL & GA) 20031009.2539
2002
---
Tomato spotted wilt, tomato - USA (MA): Correction 20020627.4618 Tomato spotted wilt, tomato - USA (Massachusetts) 20020626.4608 Tomato spotted wilt, tomato - USA (North Carolina) 20020622.4565 Tomato spotted wilt, tomato - (USA) Virginia 20020620.4545
2001
---
Tomato spotted wilt tospovirus, soybean - Iran 20011229.3130 Tomato spotted wilt, peanut - Iran 20011220.3069 Tomato spotted wilt disease, tomato - Kenya 20011109.2778 Tomato viruses - Tunisia 20010926.2349 2000
---
Tomato spotted wilt tospovirus, crops - USA (Georgia) 20000617.0989 Tomato spotted wilt tospovirus - Europe 20000302.0286 Tospoviruses - Argentina 20000213.0197 Tospovirus, zucchini, courgette & cucumber - Brazil 20000129.0145]

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