Seasonal update 2022: warm days, berry development and fungal disease management

Thursday, August 4, 2022

As in the case of a couple of weeks ago, we’re experiencing a heat wave these days. Without precipitations our soils don’t have the same moisture conditions compared a couple of months ago. It’ll be expected to see the plants a little limp, the tips starting to dry and, in some cases, where the clusters are exposed to the sun, they’ll show some symptoms as well. It’s important to keep calm, scout the vineyard and check the areas with new vines or new plantations, as these will have a less developed root system and might require some water depending on the local conditions. According to the weather forecast, next week we will receive precipitations, which will help to refill the soil profile and allow the plants to recover their turgidity through that week.

Berry growth is moving nicely through different varieties, showing a nice progress in different locations. Hybrids, as they’re ahead of vinifera ones, are showing bunch closure or very close to achieve this phenological stage. On the other hand, Vitis vinifera are growing not so far from the hybrids, it’s even possible to see some of them very close to achieve bunch closure. In the case of vinifera varieties, it’s important to keep in mind spray applications against botrytis before the bunch is close, therefore, please take a look at your records and the areas with previous disease damage, as it will be beneficial this application.

Figure 1. On the left New York Muscat and on the right Frontenac.

Figure 2. On the left L’Acadie and on the right Chardonnay.

Mentioned the last weeks, Downy Mildew pressure has been quite high and appears the risk to see Powdery Mildew as well. Therefore, it’s necessary to keep an eye in the vineyard for symptoms on the canopy or the clusters scouting at least 3 times per week to keep the vines in good health conditions.

Figure 3. Leaf with Downy Mildew.

Figure 4. Chardonnay berries this season with Downy Mildew.

In the last weeks it has been recommended to:

  • Scout minimum 3 times per week the vineyard
  • Check the most susceptible varieties, and
  • Spray according to the situation.

Moreover, it’s necessary to check other diseases as well, differentiate with other fungal diseases to spray the proper fungicide to keep control in the vineyard. For this information and to have an access to the Grape Production guide, please check the previous publication in the following link about Downy Mildew management tips