Apex method

Technical articles

Viticulture Viticulture

The apex method is a simple and effective technique used in viticulture to assess the vegetative growth of the vine and estimate the level of water stress. This method, based on observing the tip of the shoots (called apex), allows winegrowers to monitor the growth evolution of their vines and adapt their cultural practices accordingly.

Principle

The method consists of observing and classifying about 50 vine apices in a plot into three categories:

1. Full growth
2. Slowed growth
3. Stopped growth

This classification allows calculating a synthetic index called the apex growth index (iC-Apex), which characterizes the vegetative growth of the observed area.

Practical implementation

To apply the apex method, winegrowers must follow these steps:

1. Observe at least 50 apices on one or two previously identified and marked rows.

2. Classify each apex into one of the three categories mentioned above.

3. Calculate the growth index (iC-Apex) using the following formula:

   $\text{iC-Apex}=(\mathrm{\%}\text{growing apices}\times 1)+(\mathrm{\%}\text{slowed apices}\times 0.5)+(\mathrm{\%}\text{stopped apices}\times 0)$

ApeX Vigne mobile application

To facilitate the use of this method, the French Institute of Vine and Wine (IFV) and Montpellier SupAgro developed a free mobile application called ApeX Vigne. This application allows users to:

• Count and classify apices easily
• Automatically calculate the vegetative growth index
• Monitor the growth evolution of apices for each plot
• Interpret the level of water stress based on observations made

Interest for winegrowers

The apex method offers several advantages for winegrowers:

• Quick assessment of vegetative growth (about 5 minutes per plot)
• Estimation of water stress level
• Decision support for irrigation management
• Weekly monitoring of growth dynamics
• Complementarity with other measurement methods (tensiometry, modeling)

Limitations

Although the apex method is widely used, it is important to note that it has been mainly validated on five grape varieties: grenache, mourvèdre, cinsault, syrah, and carignan. However, experts believe the method can be extrapolated to other grape varieties.

In conclusion, the apex method, combined with the ApeX Vine application, offers winegrowers a simple and effective tool to monitor the growth of their vines and optimize their cultural practices, especially regarding irrigation.