Monday, August 8, 2011

Relax Fellows, Life Is Good

Customers have been asking what my badly dented crystal ball has to say about the corn planted in June. 
They are actually asking two questions.  Will my crop make maturity?  How will it yield?
The first question is easy, because the short answer is yes.  Corn planted in June responds by using less heat to get to tassel than corn planted in May.  It is a built in safety defense mechanism to save itself in shorter growing years.  Using local figures, May 10 corn needed about 1700 heat units to reach tassel and June corn reached tassel with about 1450 heat units.
The normal silking date for corn in our area is the last week in July through the first week in August, so the June corn is pretty much on schedule.
This is one June field that you can see was tasseling last week with silks beginning to emerge.

It has been a week since these pictures were taken, so pollination will be moving along quickly.
After pollination, corn advances through 5 stages of 12 days each, or a total of 60 days, to reach physiological maturity.

1-12. Milky embryo or blister stage
12-24. Young sweet corn stage
24-36. Beginning dent stage
36-48. Half milk line stage
48-60. Hard dent stage

Corn pollinating in early August will be frost hardy by early October. 

The average fall frost date for this part of Ontario is the first week in October.  Problem solved, June corn has an excellent chance to make maturity thanks to the warm June and July.

How will the June corn yield?  Today my crystal ball says very well.  But my crystal ball also predicts the May corn to be a bit better.  This is because early grain fill for May planted corn is done during longer daylight hours.  Yield is a function of turning sun energy into plant energy.  Daylight is a huge factor, along with moisture availablity and plant health.  Heat during grain fill is not as important as it is during early growth. 

Heat becomes more important in the drydown phase, but there will be time to talk about that later.

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