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Multiple viruses on capsicum in California, USA
A ProMED-mail post Date: Mon 25 Aug 2014 Surprising spring viruses in bell peppers ----------------------------------------- The 2014 spring cropping season in the Coachella Valley [Riverside County, California] brought quite a few surprises in the way of virus diseases for bell pepper growers. In February [2014], _Tomato spotted wilt virus_ (TSMV), vectored by thrips, was found in one field. The thrips could have arrived with transplants, indicating the need to inspect for insects and disease prior to planting. In April [2014], the aphid-vectored _Alfalfa mosaic virus_ (AMV) appeared [and] soon spread. In May [2014], _Cucumber mosaic virus_ (CMV), vectored by aphids, was found. In the fields infected with CMV, significant yield losses occurred. Since fields are planted next to each other it is not uncommon to see CMV hotspots in this area. Also in May, we received complaints about a red bell pepper field which allegedly had nematode damage. The described symptoms were leaf whitening and bleaching of the newer growth [and] were widespread. Since virus symptoms can overlap, we collected plant and soil samples [and] found _Beet curly top virus_ [BCTV] svr [curly top, severe strain]. Root-knot nematode levels were very similar to previous years from soil around plants displaying symptoms. What was new was the interaction of BCTV-svr. The affected plants had smaller roots and smaller fruit than healthy plants, [but] symptoms were not typical for this virus. In June [2014], fresh samples were collected [which] were found positive for BCTV-svr and AMV. The symptoms were different from those seen in fields infected with AMV at the earlier stage. These results linked the 2 viruses with the chlorosis observed in the field. Sometimes a crop can be infested with a combination of pests -- from nematodes to insect pests and viruses -- and the symptoms can be different from what is typical. [byline: Jose Luis Aguiar, Antoon Ploeg] -- 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 and can cause total crop loss. Early symptoms are often difficult to diagnose. TSWV is transmitted by various species of thrips, but is not seed transmitted. Transmission by mechanical means has been reported and 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. Host resistance breaking strains of TSWV on capsicum and tomato cultivars have been reported in recent years. _Alfalfa mosaic virus_ (AMV; type member of genus _Alfamovirus_) is transmitted by several aphid species and has a wide host range. It is also seed borne in lucerne (alfalfa) and spread to surrounding crops is common, but related to overall aphid activity. Capsicum varieties resistant to AMV are not available. _Cucumber mosaic virus_ (CMV; type member of genus _Cucumovirus_) is found worldwide affecting a large number of hosts, including many crops. It exists in numerous strains which may vary in their host range, symptoms, and means of transmission. In most hosts, it produces a systemic infection affecting newly formed tissues. It is one of the most important viruses of capsicum crops. In early infections, both quality and quantity of fruit are affected. CMV can be transmitted by more than 60 species of aphids. It can also be spread with infected plant material and very effectively by mechanical means. Seed transmission to varying degrees has also been reported in some host species, including some weeds. Disease management is difficult, since aphid vectors and virus reservoirs are widespread. Use of certified virus free planting material is essential. Control of weeds surrounding cropped fields has shown some success. Host resistance is available in some crops but may only be effective against some of the virus strains. _Beet curly top virus_ (BCTV; genus _Curtovirus_) causes curly top disease of tomato and capsicum which reduces plant vigour and can severely affect yield or even kill the plants. In California, tomato crops were severely affected by this disease in 2013 (ProMED-mail post 20140214.2277016). The virus has a wide host range and also affects other crops, including beans, spinach, sugar beet, cucurbit vegetables, as well as a range of ornamental and weed species. BCTV is spread by the beet leafhopper and can also be transmitted by grafting. The virus overwinters in the vector insects which migrate in spring and spread the virus. Weeds and volunteer crop plants may serve as vector and pathogen reservoirs. Disease management is difficult but may include control of vector insects and reservoir plants or cultural methods. Root knot nematodes (_Meloidogyne_ species) attack a wide range of plants and cause significant economic losses in many vegetable and fruit crops. For more information see links below and previous ProMED-mail posts in the archives. Symptoms can be influenced by environmental and host factors, as well as by interactions of different pathogens. Therefore, they cannot be considered a reliable means of pathogen identification. The report above illustrates the importance of molecular diagnostics for crop health. Maps USA: <http://www.mapsofworld.com/usa/usa-state-and-capital-map.html> and <http://healthmap.org/promed/p/5514> California: <http://www.mapsofworld.com/usa/states/california/california-map.html> and <http://geology.com/county-map/california-county-map.gif> Pictures TSWV on capsicum: <http://www.longislandhort.cornell.edu/vegpath/photos/pepper_tswv.htm> and <http://vegetablemdonline.ppath.cornell.edu/PhotoPages/Tomatoes/Tom_SpWilt/Tom_SpWiltFS14.htm> TSWV on a range of hosts: <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> Thrips: <http://www.insectimages.org/images/768x512/4387048.jpg> AMV on capsicum: and <http://vegetablemdonline.ppath.cornell.edu/Images/Pepper/PepperViruses/PepperVirusCollage.jpg> CMV on capsicum: <http://www.longislandhort.cornell.edu/vegpath/photos/pepper_cmv.htm> BCTV on bell pepper: Photo gallery of curly top on other crops via: <http://www.forestryimages.org/browse/subimages.cfm?sub=11199> Beet leafhopper vector: <http://cals.arizona.edu/yavapai/graphics/beetleafhoper.jpg> and <http://www.cals.uidaho.edu/edComm/keys/images/plates/plate10.JPG>
Links TSWV information: <http://vegetablemdonline.ppath.cornell.edu/factsheets/Virus_SpottedWilt.htm>, <http://www.ipm.ucdavis.edu/PMG/r783102211.html> and <http://www.tomatospottedwiltinfo.org/vegcrops/index.html> TSWV description: <http://www.dpvweb.net/dpv/showdpv.php?dpvno=412> and <http://ictvdb.bio-mirror.cn/ICTVdB//00.011.0.05.001.htm> Break-down of TSWV resistance in capsicum and tomato: <http://www.bspp.org.uk/ndr/july2004/2004-34.asp> and <http://www.bspp.org.uk/ndr/jan2005/2005-08.asp> AMV disease on capsicum: <http://203.64.245.61/fulltext_pdf/FLYER/f0093.pdf> and <http://www.ipm.ucdavis.edu/PMG/r604101011.html> CMV disease on capsicum: <http://vegetablemdonline.ppath.cornell.edu/factsheets/Virus_Pepper.htm> CMV on other hosts: <http://www.extento.hawaii.edu/kbase/crop/type/cucvir.htm> CMV information and description: <http://www.dpvweb.net/dpv/showdpv.php?dpvno=400> and <http://ictvdb.bio-mirror.cn/ICTVdB/00.010.0.04.001.htm> Information on curly top disease: <http://entoweb.okstate.edu/ddd/diseases/curlytop.htm>, <http://cals.arizona.edu/yavapai/anr/hort/byg/archive/curlytopvirus2013.html>, and <http://www.ipm.ucdavis.edu/PMG/r783102011.html> BCTV description: <http://www.dpvweb.net/dpv/showdpv.php?dpvno=210> _Curtovirus_ species and strains: All virus taxonomy via: <http://ictvonline.org/virusTaxonomy.asp?version=2012> Information on plant virus vectors via: <http://www.cals.ncsu.edu/course/ent425/text18/plantvectors.html> Information on root-knot (and other) nematodes: <http://cals.arizona.edu/pubs/diseases/az1187.pdf> and <http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7489.html#LIFE> - Mod.DHA]
[See Also: Curly top, tomato - USA: (CA) new strains susp. 20140214.2277016 2013 --- Curly top, tomato - USA: (CA) 20130607.1760251 2012 --- Cucumber mosaic virus, muskmelon - India: (PB) susp. 20120509.1128172 2011 --- Cucumber mosaic virus & mildew, muskmelon - India: (PB) 20110505.1385 2010 --- Tospovirus complex, tomato - Brazil 20100719.2419 Viruses, virus-like pathogens - Pacific Islands 20100514.1572 2009 --- Banana viruses - Philippines (02): (CT) abaca ban 20091113.3926 Viruses & bacteria, multicrop - Solomon Islands 20090304.0887 Banana viruses - Philippines 20090204.0486 2008 --- Undiagnosed diseases, passionfruit - Kenya: (Rift Valley) 20081217.3961 Novel pathogens, tomato, potato - USA 20080820.2593 Cucumber mosaic virus, yams - West Africa 20080505.1533 Tomato spotted wilt virus, capsicum - Spain (Almeria) 20080123.0280 2007 --- Tomato viruses TSWV, TICV - Jordan: 1st reports 20071223.4123 Viruses, sweet potato - Papua New Guinea, Solomon Is. 20070901.2880 Iranian beet curly top virus, multicrop: 1st report, new curtovirus 20070712.2228 Viruses, sweet potato - worldwide: synergism 20070624.2042 Tomato spotted wilt virus, tomato - USA (CA) 20070608.1872 and older items in the archives] A ProMED-mail post ProMED-mail is a program of the International Society for Infectious Diseases <http://www.isid.org> More news from: ISID (International Society for Infectious Diseases) Website: http://www.isid.org Published: September 1, 2014 |
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