The 2017 season has seen normal to above normal accumulation of corn heat units (CHU) in most areas from May 1st to August 13th: http://www.gov.mb.ca/agriculture/weather/pubs/percent-normal-chu.pdf.
So as we inch closer to September, producers start to wonder when their grain corn may reach physiological maturity (R6). At this stage, kernels have reached maximum dry matter accumulation and kernel moisture can range between 30 to 35% (but can vary by hybrid and environment). But more importantly, at physiological maturity the grain corn crop will be safe from a killing frost.
The following table was modified slightly from the original table found in NDSU’s Crop & Pest Report August 8, 2013. The table relates calendar days to corn kernel development and yield in general terms.
Table 1: Relationship between corn growth stages and calendar days to maturity, yield loss, and other kernel characteristics
The ranges listed are fairly large in order to take into account variances in temperature (climate) and the relative maturities of the hybrids grown (genetics). It is also important to remember that the various plant stages and the duration of those stages can also be influenced by soil fertility, cultural practices (plant populations) and water availability (dry conditions can hasten maturity).
Source: NDSU Crop & Pest Report August 8, 2013 http://www.ag.ndsu.edu/cpr/plant-science/characteristics-of-late-maturing-corn-08-08-13
Originally Posted on Crop Chatter in August 2016
Last Revised August 2017