In March, winter gives way to the first signs of spring, with rising temperatures and longer days. The streets come alive with café and restaurant terraces, inviting us to find a table and enjoy a glass of wine.
This is also the month when the vineyards begin to awaken from their long winter dormancy. Their biological activity resumes, activated by warmer temperatures and more daylight hours. It is the season of ‘sap bleeding’, when the sap seeps from the vines’ pruning cuts.
The growth cycle has commenced – not only for the vine, but also for other vegetation, the unfairly maligned weeds. Removing these wild plants often becomes necessary to prevent them from directly competing with the vines for nutrients and water. In the vineyard, herbicides represent the most commonly used method.
Herbicides might be accepted and widely used in farming, but in recent years they have been linked to soil erosion on agricultural land.
Do sustainable and effective alternatives to these products exist? Although there is no single definitive answer, the number of initiatives is on the rise, and as a result, so is their effectiveness.
In New Zealand, for example, winegrowers have used techniques like planting and cutting back cover crops as a form of weed control for over 20 years. These actions are carried out as part of the Sustainable Winegrowing NZ programme.
In the US, growing environmental awareness and herbicide-resistant weeds have led wine producers to work with cover crops like grasses and legumes. Winegrowers in Oregon have seen successful results in Chardonnay vineyards (Fredrikson et al., 2011).
In 2018, the European Commission emphasized (p. 2, Issue 504, 2018) the effectiveness of these practices as alternatives to herbicides, because they conserve biodiversity and allow for the growth of beneficial vegetation like certain grasses and legumes.
Are all weeds bad?
Not according to the Australian Ministry of Agriculture. Some of them protect the soil from the damaging effects of the sun, wind, and rain. They also provide a food source for pollinating insects and prevent the growth of harmful weeds. In addition, certain weeds that are harmful in one vineyard can be beneficial in another located elsewhere due to differences in soil composition, climate, age of the vineyard, and the individual goals of the winegrower.
Personally, I have observed the promising results of working with animals to eliminate weeds in rural areas of Galicia. The Misión Biológica de Galicia launched an initiative to use sheep grazing as an alternative to chemical products. The project was a success and showed that animals can help winegrowers rid their vineyards of unwanted vegetation.
There might not be one sure-fire technique to eliminate chemical herbicides from the vineyard, but these sustainable strategies gravitate towards traditional methods such as tillage and cover crops. Giving priority to natural alternatives in the vineyard is essential to preserving soil fertility and maintaining the vegetative-productive balance.