Tomato bronze stain virus
| Tomato bronze stain virus | ||||||||||||||||||||
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| Tomato spotted wilt tospovirus | ||||||||||||||||||||
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| TSWV | ||||||||||||||||||||
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The tomato bronze stain virus , colloquially also often called bronze stain virus , is a plant virus that occurs very frequently in horticulture . It is a plant virus of the genus Tospovirus from the family Peribunyaviridae (formerly Bunyaviridae ). The virus is spread worldwide and is internationally abbreviated as TSWV ( English: t omato s potted w ilt v irus ). It affects tomatoes less often, but is one of the most important viruses in this culture. Many other vegetables, ornamental plants and wild plants can also be infected.
Biological properties
More than 900 possible host plants are known for the bronze spot virus . It is known as the Emergent Virus . The virus is one of the few that is only transmitted as vectors by thrips . In Central Europe, Californian flower thrips ( Frankliniella occidentalis ), onion or tobacco thrips ( Thrips tabaci ) and black bladder thrips ( Thrips fusca ) play a role. The main route of distribution, however, is the introduction of young plants. In addition, the virus, often starting from infected ornamental plants or weeds, is later transmitted to tomato crops by vectors. Transfer with sap that sticks to working tools is also possible. However, little importance is attached to this transmission path. So far, the virus could not be transmitted via seeds.
Symptoms
Tomatoes and bell peppers often do not show the symptoms for a long time, which makes detection in young plants impossible without testing by a laboratory. The first symptoms appear on the leaves through slight lightening of the veins and faintly visible concentric rings. The latter symptom also occurs on the fruits. However, the appearance is quite different from variety to variety and depending on the time of infection. Mostly, light green to yellowish, red to purple discolorations, stripes and ring-like spots appear on the leaves, fruits and stems of the plant, which look like bronze. Black spots the size of a pinhead and three to eight millimeters in diameter are also possible on the leaves. The fruits are crooked and deformed and show similar color symptoms as other parts of the plant. Most of the colors of ripening fruits are red. The coloring of the green parts of the plant contributed to the naming of this virus disease.
Ornamental plants respond to the virus with brown, sickle-shaped spots that are often arranged around the central vein. Deformations of the leaves and shoots are also known. In particular, the flowering performance, which is important for ornamental plants, is adversely affected and growth is slowed down.
Distinction
In contrast to the cucumber mosaic virus , which is also found on tomatoes, necrotic stripes usually appear on the stalk of the bronze spot virus in the shoot tip.
Countermeasures
In order to avoid transmission by thrips, weeds in the cultivation of tomatoes should be eliminated and the joint cultivation with ornamentals should be avoided. If diseased plants are found, they should be removed from the stand immediately to prevent transmission to other plants. Direct control is not possible due to the lack of chemical products in plants. Thorough treatment of the thrips, which act as vectors, is important. However, controlling thrips is difficult and seldom completely possible. Therefore, resistances were sought and these crossed into newer varieties. There are varieties of peppers and tomatoes that are resistant to this virus. However, it is known from Italy that the resistance was broken by new variants.
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Individual evidence
- ↑ ICTV Master Species List 2018b.v2 . MSL # 34, March 2019
- ↑ a b ICTV: ICTV Taxonomy history: Akabane orthobunyavirus , EC 51, Berlin, Germany, July 2019; Email ratification March 2020 (MSL # 35)
- ↑ a b c d e f G. Crüger, GF Backhaus, M. Hommes, S. Smolka and H.-J. Vetten: Plant protection in vegetable cultivation , 4th edition, ISBN 3-8001-3191-9 , 2002, p. 205.
- ↑ a b c S.T. Koike, P. Gladders and AO Paulus: Vegetable Diseases - A Color Handbook , Academic Press (Elsevier), ISBN 0-1237-3675-7 , 2007, pp. 218–219 + 364–365.
- ^ R. Fritzsche and R. Keilbach: The plant, storage and material pests of Central Europe - with references to countermeasures , Gustav Fischer Verlag, Jena / Stuttgart, ISBN 3-3346-0531-0 , 1994, p. 74.
- ↑ a b G. Bedland: Vegetable diseases , Österreichischer Agrarverlag, Klosterneuburg, ISBN 3-7040-1565-2 , 1999, pp. 197-198.
- ↑ a b W.R. Jarvis and CD McKeen: Tomato diseases , Publication 1479 / E, Agriculture Canada, 1991.
- ↑ a b W. Gerlach et al .: Plant protection in ornamental plants , Eugen Ulmer KG, ISBN 3-8001-4409-3 , 2006, pp. 127 + 166.