GDD & PHENOLOGY TRACKER

Growing Degree Days (GDD) Tracker 

Introduction: Growing Degree Days (GDD) is a measure of heat accumulation based on the daily temperature. GDD helps to indicate and assess crop growth stages such as plant emergence, bud burst, flowering and crop maturity during the growing stage. We start to calculate GDD depending on the crop and their GDD models. From the start calculation date, each date will generate a GDD value based on its daily temperature. The accumulation of daily GDD will help to determine where your wild blueberry field stage is at, compared to the model we used in Nova Scotia. Here is a factsheet to help you understand GDD in Wild Blueberry Production: https://www.perennia.ca/wp-content/uploads/2022/05/Understanding-Growing-Degree-Days-in-Wild-Blueberry-Production.pdf.

 Table 1. Wild Lowbush Blueberry Growing Degree Days Model (White 2012)

Non-bearing (Sprout) Year		Bearing (Fruit) Year
Stages	Cum. Degree-days	Stages	Cum. Degree-days
Plant emergence- start	270 GDD	Stems with open flowers- start	390 GDD
Plant emergence- 10%	290 GDD	Stems with open flowers- 10%	412 GDD
Plant emergence- 25%	325 GDD	Stems with open flowers- 25%	440 GDD
Plant emergence- 50%	405 GDD	Stems with open flowers- 50%	480 GDD
Plant emergence- 90%	750 GDD	Stems with open flowers- 90%	600 GDD
Tip Dieback- start	690 GDD
Tip Dieback- 10%	834 GDD
Tip Dieback- 25%	940 GDD
Tip Dieback- 50%	1080 GDD
Tip Dieback- 90%	1475 GDD

*GDD start calculation date: April 1; Base T= 0 °C; GDD calculation method: averaging method (GDD = Tmean – Tbase)

*GDD thresholds in this table were updated on April 24, 2022, from Dr. Scott White’s research data

*Example to interpret this table: wild blueberry plant emergence starts in sprout fields at around 270 GDD

Please compare your current GDD from the interested location (weather station) to the above table and determine what stage your fields are at. Please note, that variation happens so please make your management decision after you visit your fields. 

 

Figure 1. Growing Degree Days from Weather Stations located in Nova Scotia Wild Blueberry Fields (running from April 1 to Oct 31)

*Please use the zoom-in and zoom-out functions to change the size of the map and you will be able to see the exact locations of weather stations. 

*Click on the weather station (location) you are interested to know, it will show you the most current accumulation GDD on the date reported. 

*Click on the link under "Current Conditions", and you would be able to see more detailed weather information from the station.

Percentage of Wild Blueberry Fruit Bud F2 Stage Tracker

Introduction: Wild blueberry buds are at a susceptible stage when 40% or more of flower buds are at the F2 stage. Current recommendations suggest that fungicide application be considered to protect crops when fields reach 40% F2 or above and weather conditions (temperature and wetness period) are conducive to infection.

The below map gives growers ideas of F2 bud stage development in various production areas in NS. Those data were generated based on my observation and reports from growers in those regions. Please check your field and determine your management plant. If you would like to share information with me about the blueberry plant growth stage in your areas, please contact me at 902-890-0472 or email me, at hlyu@perennia.ca. I appreciate your information.

Figure 2. Percentage of Wild Blueberry Fruit Bud F2 Stage Tracker in NS (running during floral bud development period)

*Please use the zoom-in and zoom-out functions to change the size of the map and you would be able to see more bud development in different data available locations. 

*Click on the location you are interested to know, it will show you % F2 in that area and location (data collected date)

*Please note, light green (0-20% F2), dark green (20-30% F2), yellow (30-40% F2) and red (40-100% F2). Once you see yellow points in your interested areas, plan and watch for the weather; if you see red points in your interested areas, plan to apply products to avoid disease infection in those fields.