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Red node disease on beans in Florida, USA

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: Fri 10 Jan 2020

Source: University of Florida, Institute of Food and Agricultural Sciences (UF/IFAS) [edited] <http://blogs.ifas.ufl.edu/miamidadeco/2020/01/10/bean-red-node-disease-threatening-vegetable-industry-in-miami-dade/>

A severe outbreak of red node disease caused by tobacco streak virus

(TSV) in snap beans has occurred in a number of fields, which resulted in significant yield losses. Some growers have to completely destroy their crops without harvesting at all. The efficient control and management of such fatal disease is very challenging. Thrips [are] a vector for the disease. However, [there is] a lack of efficacy in chemical control or IPM [integrated pest management] because of insect resistance.

Growers are frustrated and struggling against this disease, which is severely threatening the local vegetable industry. Red node is not a new disease but it has never been so severe as in this [2019/20] growing season.

Symptoms are reddish discoloration of nodes, in severe cases plants will break. Leaf veins exhibit reddish-brown streaking. Reddish-brown rings may appear on pods, which become shriveled or puffy and do not produce seeds. Plants can be severely stunted and killed.

Environmental factors may also contribute to the disease. [Use of] pathogen free seeds is important because seed transmission has occurred in beans, chickpeas, and weeds.

[Byline: Qingren Wang]

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

[_Tobacco streak virus_ (TSV; type member of genus _Ilarvirus_] has a wide host range, including a number of crops such as vegetable bean (_Phaseolus vulgaris_), sunflower, peanut, maize, and soybean. It is probably distributed worldwide and has been reported to be spreading in North America and Oceania. Many viral variants exist in different regions and/or different hosts. Bean red node disease is considered to be caused by a distinct strain.

The virus is transmitted by thrips vectors (_Frankliniella occidentalis_ and _Thrips_ spp.), possibly by allowing virus from the surface of infected pollen to enter through feeding wounds. TSV can also be spread by mechanical inoculation, grafting, and by pollen to the pollinated plant; it is seed-transmitted in some species to different extents. Weedy hosts, for example _Parthenium_ species, may serve as pathogen reservoirs and potential sources of infected pollen (see previous ProMED-mail post no.

http://promedmail.org/post/20070419.1289). TSV is not transmitted by contact between plants.

Disease management is difficult and requires an integrated approach which may include vector control (for glasshouse crops), use of clean planting material (including seeds), control of weed hosts of virus and vectors, phytosanitary measures, as well as use of resistant crop cultivars if available.

Maps

USA:

<https://www.mapsofworld.com/usa/large-us-map.html> and <http://healthmap.org/promed/p/4730>

Individual states via:

<http://www.mapsofworld.com/usa/usa-state-and-capital-map.html>

Pictures

Red node disease on bean:

<http://nwdistrict.ifas.ufl.edu/phag/files/2016/09/Funderburk-Fig3_TSVBeanRedNode.jpg>,

<https://nwdistrict.ifas.ufl.edu/phag/files/2016/09/Funderburk-Fig4_TSVPodSymptoms-768x614.jpg>,

<https://d3qz1qhhp9wxfa.cloudfront.net/growingproduce/wp-content/uploads/2014/11/tobacco_streak_virus.jpg>,

via

<https://www.ipmimages.org/browse/Areathumb.cfm?area=89>, and <https://plantpath.ifas.ufl.edu/u-scout/bean/red-node.html>