By Ryan Miller
Environmental stresses
The “heat dome”, hot temperatures during the early reproductive stages of corn development, what does it mean for Minnesota’s corn crop? The Minnesota corn crop is about a week ahead of normal and currently has adequate moisture but limited precipitation or chances for precipitation means things are drying out. Fortunately, the temperature conditions are expected to be cooler this coming week.
So how is the heat affecting corn that is pollinating or starting to pollinate? Current high temperatures have been in the low 90’s, and corn can tolerate those temperatures without issue. Things have been drying out with the lack of precipitation and during hot dry conditions we can see tasseling speed-up and silking slow down a bit, so some of the later emerging silks might not get pollinated under stressful conditions. Air temperatures in the mid-90s or above reduce pollen viability, but that is generally not a concern because most pollen shed occurs in the morning hours while temperatures are cooler. Cooler temperatures next week will benefit Minnesota’s corn crop as more corn starts to pollinate and corn that has been pollinated enters a critical phase of kernel retention.
A few days after pollination has started you may want to check if you had successful pollination. Silks grow about an inch per day and silks that have not been pollinated will continue to grow longer. To check pollination growers can carefully un-husk an ear and gently shake the cob to see if silks detach, silks that detach from the ear indicate successful pollination and silks remaining attached indicate they have not been pollinated. With modern hybrids, tassel emergence and silking tend to be quite synchronous, tassels will continue to drop pollen for several days after they start pollen release.
Ranking the critical periods for environmental stress and corn yield potential. The most important is the week of pollination (10 of 10), then the two weeks after silking (9 of 10), and then three to four weeks after silking (8 of 10). During this period we can see stress affect pollination and kernel retention.
Source : umn.edu