ISHS Acta Horticulturae 473: International Symposium on the Importance of Varieties and Clones in the production of Quality Wine
GRAPEVINE SANITARY SELECTION AS A SCREENING METHOD FOR CLONES |
| Authors: | Z. Korošec-Koruza, A. Topolovec, B. Koruza, I. Tomazic |
| Abstract:
In Slovenia more than 70 V. vinifera cultivars are grown and all of them are included in standard positive mass selection. This selection comprehends the five years individual pomological evaluation of the tentative mother vines. For about 90,000 vinifera and 35,000 rootstock vines the selection has been finished already, for 240,000 vines the procedure will be concluded in the following years. Clone selection originates back to 1956 when the first clones of 'Laški rizling' ('Welschriesling') and 'Sauvignon' were selected. The work was centralised and supported by the Ministry of Agriculture. Five years in a row all the vines were inspected for the known symptoms of virus diseases, (infectious degeneration, leaf roll and rugose wood), and lately they are also being inspected for "Flavescence dorée" and Yellows, the phytoplasma diseases. In preliminary ELISA screening (Korošec-Koruza, 1992) we found out that about 12% of infectious degeneration and up to 38% of leafroll and similar diseases were not detected in field inspections due to their latency. Sanitary selection with ELISA and indexing has been proposed in 1990/91 for all former and new clones. Therefore two selection stations - nuclei were formed (Ormoz for the continental and Vipava for the littoral part of the vineyards). Their program is based on the international guidelines proposed by I.C.V.G. and O.I.V. (Frison and Ikin, 1991, Walter and Martelli 1996, Walter and Martelli 1997). In indexing procedures the traditional grape green-grafting was used. The grafts were enhanced in mist chamber. Standard indicator vines were used, as well as some of our local vinifera varieties ('Zametovka'). The virus free status of our own indicators was obtained by meristem culture (6). For ELISA, leaf samples (for NEPO viruses only) were collected in May, or wood shavings were used during winter dormancy. Sanofi -Plantest and Bioreba ELISA test diagnostic kits were used for GFV, ArMV, GLRaV I and III, and GVA. Some 400 elite plants issued out of the standard selection and old clones of 20 cvs and 5400 plants of new clone selections have been tested already. We performed 2000 to 3500 tests/year, the detectability and reliability of the tests is high enough (96%) to use the ELISA as a routine test in clone selection. 20% of vines tested with ELISA were included in the indexing and were observed for two years. Local white cultivars ('Zelen', 'Glera', 'Rebula', 'Vitovska grganja', 'Danijela', 'Poljsakica', 'Volovnik', 'Cividin') expressed high incidence of GFV (38%) and lower (8%) for closteroviruses. The drop of potential clone candidates for some varieties is more than 90%. The economically important cultivars were submitted to further meristem culture to avoid risk and long lasting search for one pomological and sanitary suitable plant of a variety. No ArMV infections were detected in the old varieties (Koruza and Sibila Jelaska 1993). For the Karst red cv. 'Refošk' with 52 clone candidates, 5% were GLRaV I and 10% were GLRaV III positive. The last five years no natural spread of the leafroll has been observed in the clone vineyard. Two of the clone candidates with each 20 offsprings, expressed a severe rugose wood in the field. The one with symptoms only on the vinifera part of the trunk gave complete GLRaV I positive reaction, the other one with the rugose wood on the rootstock (SO4) gave negative ELISA. There was no positive reaction in indexing. From previous research we know that the cv.'Refošk' was heavily infected with | |
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