Growth Stage 30, PGR Timing and More

The field season is well underway with much of the nitrogen on winter wheat, spring cereals being seeded and herbicide, fungicide and plant growth regulator (PGR) applications planned for the coming weeks. And yes, it is only April 16th!  The early spring brought a lot of excitement to the wheat crop with the recent rains being welcomed to help slow the pace.

 

Many are commenting this is one of the earliest springs they can remember, so the question is, are we early and by how much? When looking at Growing Degree Day (GDD) accumulations (a weather-based indicator for tracking and predicting cereal growth and development) since March 1st, accumulations are well above the 9-year average in many areas (Table 1). This would be why many early-planted fields are at or approaching Growth Stage (GS) 30 and why paying attention to growth stage rather than the calendar date is important.

 

 

GS 30 is important in winter wheat because this is when plants shift from vegetative to reproductive growth.  All meaningful tillering has been completed and the main stem and tillers start to synchronize. This stage is critical for nitrogen applications in order to influence the number and size of seeds on the head. This stage is also the beginning of the optimum window for PGR applications. Many early-planted fields are at or approaching this growth stage. Later-planted fields in Ontario are still at the tillering stage.