Identifying grape rootstock can be a challenging task, but there are several methods and techniques that can be used to determine the rootstock of a grapevine. Here, I will share some insights on how to identify grape rootstock based on my experience as a sommelier and brewer.
1. Visual Examination: One of the first steps in identifying grape rootstock is through visual examination. Look for specific characteristics such as leaf shape, color, size, and the arrangement of veins. Different rootstocks may have distinct leaf characteristics that can help in the identification process. For example, some rootstocks may have larger leaves with more pronounced lobes, while others may have smaller leaves with a different shape.
2. Observation of Shoots and Canes: Another important aspect to consider is the growth pattern of the shoots and canes. Pay attention to the color, thickness, and texture of the shoots and canes. Some rootstocks may exhibit specific growth patterns, such as a more vigorous or compact growth, which can provide clues about the rootstock.
3. Analysis of the Vineyard: Understanding the history and management practices of the vineyard can also offer valuable insights. If the vineyard has a record of the rootstocks used, it can significantly narrow down the possibilities. Additionally, observing how the vines perform in terms of vigor, disease resistance, or tolerance to specific soil conditions can provide further indications of the rootstock.
4. Soil and Climate Analysis: Soil and climate conditions play a significant role in determining the suitability of a rootstock. Different rootstocks have varying tolerances to soil pH, moisture levels, and temperature extremes. By analyzing the soil composition and climate conditions of the vineyard, you can make educated guesses about the rootstock based on its known preferences.
5. DNA Testing: While visual examination and analysis can provide valuable information, the most accurate method to identify the grape rootstock is through DNA testing. DNA testing can determine the specific genetic makeup of the vine, confirming its rootstock identity beyond any doubt. Foundation Plant Services is a reputable institution that offers DNA testing services specifically for grapevines. Although this method incurs a cost, it is the only way to definitively determine the cultivar or rootstock identification.
In my experience, a combination of visual examination, analysis of growth patterns, understanding vineyard history, and considering soil and climate conditions can often provide a good indication of the rootstock. However, if you want to be absolutely certain about the cultivar or rootstock identification, DNA testing is the most reliable and accurate method.
Remember that identifying grape rootstock can sometimes be challenging, especially in cases where multiple rootstocks have been grafted onto the same vineyard. Therefore, it is essential to gather as much information as possible and seek professional assistance if needed.