Growing Degree Days (GDD) Summary
Here is a summary of the most up-to-date GDD from 13 weather
stations in wild blueberry fields.
Figure
1. GDD Summary, April 25, 2023
For fields/areas with GDD
above 150 GDD, pre-emergence herbicides (chikara, ignite, velpar, spartan etc.)
can be applied now, but please watch the 213 GDD threshold as after 213 GDD, plants
are actively growing and damage could occur to newly emerged tissues.
For crop fields and monilinia,
some very early fields (fields in the Southshore counties and fields around Newville
Lake and Halfway River in Cumberland County) are at or above 40% F2, but based
on the weather forecast for those areas, an application can be made until next
rain and wet period. Most average fields in Colchester and Cumberland are
around 20% F2. Fields in Pictou, Antigonish and Cape Breton are still looking
in between 5%-10% F2.
After fields reach 40% F2
and above, a Monilinia blight application should be made before a forecasted
wet/rainy period. But, if it is forecasted to be a dry period, then an application
can wait until before a wet period. If we are getting average temperatures of
10 or 14 degrees Celcius, a 6- 8 hours wetness duration could bring a high risk
of infection (Figure 2).
Figure
2. Severity Rating of Monilina Infectinn Periods