On the 20. of March, spring arrived in the Northern hemisphere, and with warmer days, nature is slowly waking up from winter hibernation. Depending on the wine-growing region, March and April are the months when vines wake up and start to grow in the Northern hemisphere.
The season of vine growth is closely linked to the daily air temperature and soil temperature at a depth where most of the roots are located. When in the early spring, the average daily temperatures reach 8-12°C, the “vine juices” (water containing a low concentration of organic acids, hormones, minerals, and sugars) start to flow (from the root system upwards to the vine parts above the ground). Bud swelling begins when the soil temperature at approximately 40-60 cm depth rises to 7-8 °C. At that time vine start to “bleed,” which means that “vine juices” starts to drain from the cuts (or “wounds”) on canes and cordons left over from the winter vine pruning. Budburst in the Northern hemisphere usually starts in late March or early April if the temperatures are appropriate. That is when the average daily temperature for a longer period exceeds 10 °C. In colder spring, the budburst can be delayed to the start or the second half of April, depending on the vine-growing region. Budburst starts because “vine juices” flow up from the roots towards the buds, which begin to swell and force the buds to open – “burst.”
During this time, the temperatures are also suitable for the development of most of the vine pests. As soon as the bud burst starts and the first leaves are unfolded, there is a threat of fungal disease development. Since no grower wants fungal disease on their vines, it’s crucial to suppress vines against primary fungal infections. And since we are all responsible for taking care of the environment, and no one wants to eat grapes or drink wine full of pesticides, it’s important to spray and protect vines only when the weather is suitable for fungal development. A great way to know the appropriate time to protect vines against specific fungal diseases is to use a decision support system, which helps you decide the best spray timing.
The amount of rain that falls in spring is closely related to primary infection pressure. Therefore, by knowing the exact amount of rainfall in your vineyard, you can decide the best spraying time and adjust the times between spraying. On the other hand, spring rainfall is the most welcome to moister soil and gives vines the best chance to grow and develop healthy canopies.
Since several vine diseases, pests, and vineyard management activities are related to the vine growth phase, it is super helpful for winegrowers to know and calculate growing-degree days (GDDs). GDDs start calculating at the beginning of the growing season, so the start of March or April. If you want to learn more about why it is important to calculate GDD in the vineyard, see the detailed explanation here.
Another reason why it’s best to set up a weather station in your vineyard in March and April is to give the software an opportunity to learn about the vineyard, the weather in the vineyard, and your activities from the beginning of the season. Yes, software like eVineyard can learn too. The more information eVineyard has about your vineyard and activities in the vineyard; the more knowledge absorbs and gives better and more punctual advice for you and your vineyard.
So, if you haven’t already set up a weather station in your vineyard, now is the time.
Still, hesitating?
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Sources:
Different wine growing manuals
Annual growth cycle of grapevines, Wikipedia
