Julius-Kühn-Archiv (Feb 2014)
Role of Oxalis corniculata L. as plant virus reservoir with special regard to Tomato Spotted Wilt Virus (TSWV-RB) strain occurrence in rock-wool cultivation in Hungary
Abstract
The creeping wood sorrel (Oxalis corniculata L.) in Central Europe occurs mainly in anthropogenic areas, where it grows in parks and landfill sites or in protected cultivation sites like greenhouses and nurseries. In Hungary O. corniculata has been spreading since the 19th century. In glass- and greenhouses it is the only weed species that was able to settle and flourish on hydroponic rock-wool and coconut fibre growing media. Among virus pathogens of forced tomato (LYPES) and paprika crops (CPSAN) in Hungary the Tomato Spotted Wilt Virus (TSWV) has become an important one, severely affecting the plants and on occasions causing 100% yield losses. The spread of the virus was largely assisted by its effective vector the Western Flower Thrips (Frankliniella occidentalis Pergande). Initially the control of the disease was based on the control of the thrips, later, virus-resistant varieties were introduced. This however proved insufficient to fight the disease as it was discovered, quite recently, that in certain white pepper (CPSAN) varieties the virus was able to break up the resistance. According to data of the year 2012, those varieties that were considered resistant, showed up to 50% virus infection. Considering the wide spread of O. corniculata and increasing occurrence of the resistance-breaking TSWV isolates, surveys in greenhouses were conducted to examine whether the weed could serve as reservoir for TSWV. Samples were collected of the virus infected crop plants and O. corniculata growing in the same coconut fibre cubes. The samples were examined using test-plants, serological and RT-PCR methods. In result it was found that the symptoms were indeed caused by resistance-breaking TSWV isolates. However, no virus was found in the suspected O. corniculata samples. Therefore it was concluded that in this particular case the O. corniculata cannot be considered reservoir for the virus, in the hydroponic culture.
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