Grapevine yellows (GY) are
disease
A disease is a particular abnormal condition that negatively affects the structure or function of all or part of an organism, and that is not immediately due to any external injury. Diseases are often known to be medical conditions that a ...
s associated to
phytoplasma
Phytoplasmas are obligate intracellular parasites of plant phloem tissue and of the insect vectors that are involved in their plant-to-plant transmission. Phytoplasmas were discovered in 1967 by Japanese scientists who termed them mycoplasma-lik ...
s that occur in many
grape
A grape is a fruit, botanically a berry, of the deciduous woody vines of the flowering plant genus ''Vitis''. Grapes are a non- climacteric type of fruit, generally occurring in clusters.
The cultivation of grapes began perhaps 8,000 years ago, ...
growing areas worldwide and are of still increasing significance. The most important grapevine yellows is
flavescence dorée.
Phytoplasmas are obligate cell wall-less bacterial pathogens (class Mollicutes), and rely on plants and homopterous phloem-sucking insects for biological dispersal. In plants, they are mainly restricted to the phloem tissue where they can move and multiply through the sieve tube elements. Almost identical symptoms of the GY syndrome are caused by different phytoplasmas and appear on leaves, shoots and clusters of grapevine. Typical symptoms include discoloration and necrosis of leaf veins and leaf blades, downward curling of leaves, lack or incomplete lignification of shoots, stunting and necrosis of shoots, abortion of inflorescences and shrivelling of berries. Those symptoms are related to callose deposition at the sieve plates and subsequent degeneration of the phloem. Although no resistant cultivars of ''
Vitis vinifera
''Vitis vinifera'', the common grape vine, is a species of flowering plant, native to the Mediterranean region, Central Europe, and southwestern Asia, from Morocco and Portugal north to southern Germany and east to northern Iran. There are curre ...
'' or
rootstock
A rootstock is part of a plant, often an underground part, from which new above-ground growth can be produced. It could also be described as a stem with a well developed root system, to which a bud from another plant is grafted. It can refer to a ...
s are known so far, the various grape varieties differ considerably as far as symptom severity is concerned. It ranges from fast decline and death in highly susceptible cultivars to tolerant rootstocks as symptomless carriers of the pathogen. Currently, the only available control strategies include early eradication of infected crops, early eradication of infected source plants (weed control), and chemical control
of vectors through regular insecticide treatments.
The main viticultural production areas in the Republic of North Macedonia were surveyed in 2006/2007/2008 for the presence of grapevine yellows. PCR and RFLP analyses were used to detect and identify phytoplasmas infecting grapevines. Only phytoplasmas associated with “
bois noir” disease (ribosomal subgroup 16SrXII-A or stolbur) were detected. Molecular analyses showed that all phytoplasmas identified belonged to tuf-type II (VKII).
References
External links
* https://archive.today/20120719204317/http://web.uniud.it/phytoplasma//pap/boud8290.Html
* https://web.archive.org/web/20120218082739/http://plantpathology.ba.ars.usda.gov/pclass/pclass_grapevine.html
{{DEFAULTSORT:Grapevine Yellows
Economy of North Macedonia
Bacterial grape diseases