AFTER CORN SILKS HAVE TURNED BROWN, CORN GROWTH IS CHARACTERIZED BY A PERIOD OF RAPID DRY MATTER ACCUMULATION IN THE KERNEL.

The cob has reached its full length and diameter by the roasting-ear stage. Almost all of the potassium and 70% of the nitrogen and phosphorous needed by the corn plant has been taken up from the soil. Below are some kernel development facts.

1) BLISTER STAGE - This stage occurs 10 to 14 days after silking. The kernel is white in color and resembles a blister. It contains a clear inner fluid in which the developing embryo can be seen. Starch has just begun to accumulate and the kernel is beginning its dry matter accumulation or seed fill period. The kernel is about 85% moisture at this time.

2) MILK STAGE - This stage is characterized by a yellow kernel color and the inner fluid is milky white. The milk stage occurs approximately 18-22 days after silking. The embryo can now be easily seen and the kernel is at about 80% moisture. This is also known as the roasting-ear stage.

3) DOUGH STAGE - The inner fluid in the kernel has now turned into a paste or dough like material due to accumulated starch formation. The kernel is about 70% moisture and has accumulated about half of its mature dry weight. This stage occurs about 24 to 28 days after silking.

4) DENT STAGE - This stage occurs about 35-42 days after silking. All or nearly all the kernels will be dented at the top of the kernel as a result of the starch beginning to dry down at the top of the kernel. This hard layer of starch will continue to advance towards the cob. Silage producers often refer to the boundary between the hard starch and soft starch as the milk line and use it as an indicator to signal silage harvest. Kernels will be at about 55% moisture in the dent stage.

5) PHYSIOLOGICAL MATURITY - This stage is often referred to as the black layer. Black layer formation occurs when the kernels have attained maximum dry weight. If one scrapes the tip of the kernel on the germ side, a black layer will be seen when physiological maturity has been reached. Black layer occurs about 55 to 65 days after silking and kernel moisture is approximately 35 percent.

POLLINATION IN CORN HAS VERY GOOD ODDS.

A typical corn tassel will shed between 2 and 5 MILLION pollen grains and a normal corn ear typically has 600 to 850 kernels that need to be pollinated. This means there are between 3000 to 8000 pollen grains per silk. Corn is a cross pollinated crop; by this I mean that approximately 97% of the pollen which lands on the silks is from another plant. Each kernel has a silk attached to it and this silk grows out of the ear and emerges at the tip of the husk. A corn plant's tassel will shed pollen a few days before silk emergence and will continue a few days thereafter. Pollen shed is not a continuous process. Pollen shed ceases when the tassel is too wet or too dry. Peak pollen shed usually occurs from 9 A.M. to 11 A.M. Shortage of pollen is a rare problem in corn and is almost never a limiting factor in grain yield.

WILL IRRIGATION INTERRUPT THE POLLINATION PROCESS?

First time corn irrigators often ask this question because they fear irrigation water will wash pollen off the silks. The answer to this question is No! There are two reasons why irrigation will not interfere with the pollination process. Number one, a pollen grain will germinate within minutes after coming in contact with a receptive silk. Number two, the irrigation water will not cover the entire field at the same time, 24 hours per day, for the entire pollination period. By all means irrigate if the crop is in need of water!