Jeff Franklin, from AAFC Kentville, is sharing with us this week weather information with increasing growing degree values. Precipitations have helped to refill the soil profile, grapevines are showing a positive development, grapes are still growing and, in some cases showing the first signs of veraison. In specific cases it’s possible to observe vines with sun burn from previous weeks, which is minimum and nothing to compromise this year’s production.
The first table shows the temperature base 5⁰ C and 10⁰ C from 2019 until 2022 accumulated from March 1 until August 16. At the end of each section, it’s possible
to see the average of the last 5 and 10 years respectively.
|
Category |
2019 |
2020 |
2021 |
2022 |
5 year average |
10 year average |
|
Plant development
(Base 5ºC) |
1270.0 |
1406.9 |
1443.8 |
1445.5 |
1382.3 |
1382.8 |
|
Insect development
(Base 10º) |
726.4 |
879.8 |
861.5 |
868.0 |
830.4 |
827.4 |
Figure 1. Degree day accumulations as of August 16, 2022. All data are taken from the Kentville weather
station, based on a start date of March 1, and calculated using the single sine
method.
At this time, we can see 2022 with almost the values than
2021. Compared to the 5- and 10-year average, 2022 maintains a higher
accumulation in these last 7 days. In cases where the grapes are exposed to the
sun, locations with higher accumulation of degrees and where early varieties
are present, it’s possible to see the first berries turning color.
In the following
column graph, you can see the values from 2004 until 2021 and at the end the
average of the last 5 and 10 years respectively.
Figure 2. Degree day accumulations as of August 16, 2022 base 10⁰ C. All data are taken from the
Kentville weather station, based on a start date of March 1, and calculated
using the single sine method.
The trend is similar to last week, values have increased and
it’s almost like 2021. Currently, 2022 is higher than the 5- and 10-year
average. Compared to previous seasons, 2020 and 2018 are slightly higher than
the current season and the most notorious years are 2021 and 2006. Let’s keep
an eye on how moves the rest of the week!
Last week we’ve seen the damage caused by the sun on the exposed grapes through the heat wave. This damage can stay on the grapes, it’ll be mainly on one side of the bunches, the side with more exposure to the sun. In the following photo, it is possible to see a bunch with sun burn and mechanical damage.
Figure 3. Bunch
with sun burn and mechanical damage.
Last week we shared
that many hybrids reached bunch closure and some of them were in progress. At
the beginning of this week, it was possible to see the first berries starting
veraison in the earliest hybrids, such as Castel or Lucie Kuhlmann. On the
other hand, vinifera are still in progress with good berry development and in
some cases even at bunch closure. In places with the most suitable conditions, the
next 2 weeks it might be possible to see veraison. Moreover, with veraison
approaching, it’s important to remind that this is a good time for tissue
sampling for nutritional purposes. How to proceed with this? Please,
watch the following video and
fact sheet Grape Tissue Sampling to have more
information on how to proceed.
Figure 4. On the left Castel and on the right Lucie
Kuhlmann starting veraison.
Figure 5. On the left Chardonnay
and on the right Riesling.
Quite repetitive the last month, Downy Mildew pressure has
been quite high with the current conditions, high moisture, and warm
temperatures. Even though the conditions have been changed to less humidity and
warmer, such as last week, these conditions can be suitable for other diseases such
as Powdery Mildew. It’s necessary to keep an eye in the vineyard for symptoms
on the canopy or the clusters, please take a look at the following pictures.
Figure 7. Leaf and berries with Powdery Mildew this
week.
It has been recommended the last couple of weeks 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.