By Gregory W. Roth
Corn and soybeans have survived a rough spring with challenging weather and pest concerns but yield prospects have been improving during the last two weeks as we approached silking. Observations made during this time can help to determine stand health and predict silage harvest dates.
Corn throughout the state is silking or approaching silking. Observing fields for tassel development and silking can be a diagnostic tool to look for differences in crop growth and development. Frequently, areas that have experienced stress will be shorter and tassel later. This can be a simple tool to identify stressed areas in fields from compaction or fertility issues that may need attention in the future. Ideally one should strive for uniformity of silking and pollen shed throughout the field.
Silking can also be used to predict approximate silage harvest dates. A New York study showed that corn was ready for chopping at 68-69% moisture about 800 GDD after the silking date or about 35 to 45 days depending on the weather and hybrid maturity. In our region, this should be similar or maybe a few days less. This is not perfect since there are other factors involved but it does give you a rough guideline and indication that silage harvest is on the horizon.
Drought stress can delay silk emergence in stressed fields but this is a bit unusual with modern hybrids unless stress is severe. Under good conditions, you may see silk emergence prior to pollen shed. This is not an issue since the pollen silks remain viable for some time following emergence.
Many agronomists do the shake test following pollination to assess the effectiveness of the process. I usually wait until most or all silks are brown (an indication of pollination). I slice off the ends of the ear at the base and then gently pull off the husk leaves. Then I shake the ear to see the silks that remain attached to the ear. Sometimes you will notice that silks on the end of the ear will remain attached after pollen shed is over. My colleague Bob Nielsen has developed a great video detailing the process.
A little scouting at or after silking can provide some insight into the health and development of the crop. Take some time and check fields in your area to give you a heads up on the corn yield potential and issues that might be developing.