Weather update: temperature, precipitation and even hail!

Tuesday, July 27, 2021

Jeff Franklin is sharing this week the main observations of the season in terms of temperature and precipitation until July 26. Always good to remember, this information is coming from Kentville Research Development Centre (KRDC), therefore, some differences between locations are possible to be found.

The first table shows the temperature base 5 C and base 10 C from 2018 until 2021 accumulated each year from March 1 until July 26. At the end of each section, it’s possible to see the average of the last 5 and 10 years respectively.

 

Category

2018

2019

2020

2021

5 year average

10 year average

Plant development (Base 5ÂșC)

1036.9

941.7

1031.7

1121.2

1024.0

1039.1

Insect development (Base 10Âș)

604.5

503.1

609.5

643.9

581.6

589.1

Figure 1. Degree day accumulations as of July 26, 2021.  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 degree accumulation continues as the highest of the last 3 growing seasons, which has impacted positively in grapevine growth. Compared to the last weeks, the accumulation rate has decreased due the diminishment of the temperatures the last week. However, 2021 presents the highest accumulation with 643.9 compared with the 5- and 10-year average with 581.6 and 589.1 respectively.

In the following column graph, it’s possible to see the values from 2004 until 2021 and at the end you can see the average of the last 5 and 10 years respectively.

Figure 2. Degree day accumulations as of July 26, 2021 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.

In this graph, it’s easier to see how the difference of heat accumulation compared to the last 4 seasons has decreased, the only exception being 2019. It’s quite interesting to see how 2006 had even a higher accumulation until this date, similarly as in the case of 2012 and 2013.

In terms of precipitations, last week’s event affected very differently depending on the location. Between July 21 and 22 KRDC registered 87 mm of rain, but 50 mm were received just in 45 minutes on July 21 during the thunderstorms. This precipitation was highly variable depending on the location through the province.

Figure 3. Cumulative precipitation (mm) as of July 26, 2021. All data are taken from the Kentville weather station, based on a start date of January 1.

Finally, last Thursday July 22 evening different locations through Nova Scotia had a hail event, with varying the duration and intensity. Also, in the afternoon of Tuesday July 27 some areas had hail as well. If your vineyard had some damage in the leaves and the fruit zone, which means splits of berries, it’s recommended to scout these affected areas and keep in mind potential Botrytis infections. Depending on the varieties, the grapes can be between pepper-corn size up to almost bunch closure, therefore, keep in mind an application against Botrytis to protect the areas where berries has been split. The climatic conditions these days, warm temperatures and humidity, provide good conditions for fungal disease development, such as Botrytis and Downy Mildew. Thus, scouting the vineyard at least 2 times per week is highly recommended to have an effective protection in your grapevines.



Figure 4. Grapes affected by hail last Thursday July 22.






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