By: Judit Monis, Ph.D.
This year I was invited to speak at different events organized by the Chilean Nursery Association (AGV) and Wines of Chile. While in Chile, I attended the 19th Congress of the International Council for the study of virus and virus-like diseases of the grapevine (ICVG). The ICVG meeting was held and hosted in Viña Santa Carolina Winery facilities near Santiago. While I was traveling in South America, I had an opportunity to visit vineyards in Argentina and Chile. Today I will share information I learned about winegrowing in Argentina and Chile. As you know my interests are in grapevine diseases, how to prevent disease development and spread in the vineyard. So, it will not be surprising that this article will focus on vine diseases.
Grapevine Diseases Originate Where Vitis Species Originate
It is easy to guess that grapevine pathogens (disease causing agents) originated at the same place where Vitis (the grapevine genus) species originated. These disease agents (bacteria, fungi, and viruses) were introduced to other places in the world with the propagation and planting material. Specifically, the varieties and clones that are grown in vineyards belong to the Vitis vinifera species (of Eastern European and Asian origin) while the rootstocks grown commercially belong to American Vitis species. When grape cultivation started countries were not set up with quarantine programs, neither modern diagnostic tools we use today (PCR, ELISA, etc.) to detect pathogens were available. Consequently, since the early days of grapevine cultivation European and American grapevine pathogens have been moving from one site to another for many generations.
Argentine and Chilean Grape growing Regions are Strikingly Different
Being from Argentina, I frequently visit vineyards and wineries in South America. Argentina ‘s viticulture is very different from what I am used to in California growing regions. Most of the vineyards in Argentina have planted vines on their own roots (i.e., not grafted onto a rootstock) as the philoxera pest is not commonly found in Argentine grape growing areas. Besides providing protection from philoxera, rootstocks confer resistance to nematodes, salinity, and can control the vigor of the vines in the vineyard. Consequently, more vineyards in Argentina are being planted with grafted vines, especially in Mendoza’s newer and more sophisticated growing regions (Valle de Uco). In contrast, the vineyards in Chile are very similar to the ones I visit in California and strikingly different from those in Argentina. The majority of the vines in vineyards are grafted and trained in a similar fashion to Californian vineyards. The Andes Mountains that divides Argentina from Chile influences the climatic conditions of each of the countries. Therefore, the rainy seasons, availability of water and stresses present in each winegrowing area are very different.
Grapevine Diseases are Found Wherever Grapevines are Grown
When it comes to diseases Argentine and Chilean viticulture is not different from other growing areas. As I mentioned earlier, common diseases caused by Leafroll viruses, Vitiviruses, Fanleaf, Agrobacterium, and fungal trunk diseases must have arrived on site when plant material was imported. These are important diseases that affect both grape quality, yield, and longevity of the vineyards. In Chile and Argentina, I have witnessed the presence of Syrah Decline, a disorder that affects both grafted and not grafted plants. At the ICVG meeting, Joshua Pucket from UC Davis Foundation Plant Services reported that Syrah Decline symptoms are linked to genetic markers present in certain Syrah and Shiraz clones. Interestingly, when symptomatic Syrah selections were subjected to the meristem tissue culture technique used to eliminate known viruses and viroids, the symptoms persisted, suggesting that Syrah Decline is not caused by any of these infecting agents. Research in France support these findings as symptoms are restricted to certain grapevine genotypes. The news that Syrah Decline is a genetic rather than pathologic disorder will help growers prevent planting certain genotypes to avoid loss of production. It is expected that we will learn more about this disorder as more research is published on this topic. To date, surveys in both Argentine and Chilean vineyards were not able to detect Grapevine red blotch virus (GRBV). The most likely reason for the lack of GRBV in Argentina and Chile is that these countries have historically imported grapevines from Europe and the virus so far has not been reported in EU vineyards.
None of these South American Countries have a Grapevine Clean Planting Certification Program
Grape growers and winemakers are aware of the detrimental effect of grapevine pathogens and would prefer to purchase and plant certified grapevines. Unfortunately, neither Argentina or Chile have a current certification program. In other words, certified pathogen free vines (scion or rootstock varieties) are not available. This is not completely true, as I learned that Argentina has one certified Malbec clone available. However, there is no use of having a certified scion if it is to be grafted onto a non-certified rootstock. Consequently, most nurseries and growers are grafting non-certified scion and rootstock varieties. In Argentine the grapevine certification program is going through administrative revision. The current law requires that all mother plants are tested every year using the woody indexing method. However, this is not practical as the results of this test are obtained two years after starting the index. The proposed changes include the application of molecular (PCR, ELISA) instead of biological testing (index) to detect viruses in the foundation and nursery increase blocks. In Chile, supported by public funding a virus tested germplasm collection is being preserved. It is expected that the material will become available to interested nurseries that could multiply and distribute the material for planting new healthy vineyards.
In both countries, the available planting material produced at the nurseries is not sufficient to fulfill the demand of the industry. Therefore, grafted vines can also be imported from “approved” nurseries primarily from Europe (France and Italy) and must pass the government quarantine and sanitation requirements. Generally, quarantine is done at facilities owned by the importing party as neither SENASA or SAG, the National sanitary authorities in each of the countries have the space to complete the quarantine in their facilities.
It is my hope that, with time, future changes will include the availability of certified pathogen free tested and true-to-type scion and rootstock planting material. Only with clean planting grapevine material these important wine grape growing areas will see an improvement of the health and longevity of their vineyards.
Judit Monis, Ph.D. provides specialized services to help growers, vineyard managers, and nursery personnel avoid the propagation and transmission of disease caused by bacteria, fungi, and viruses in their vineyard blocks. Judit (based in California) is fluent in Spanish and is available to consult in all wine grape growing regions of the word. Please visit juditmonis.com for information or contact firstname.lastname@example.org to request a consulting session at your vineyard.