Bill Halfman, Extension Agriculture Agent
The late, wet spring we have had so far in 2019 has delayed corn planting, more so on some soils than others. In general, if all corn in Wisconsin could be planted on one day, that optimum date would be May 1 in the south and May 7 in the north. Once corn planting is delayed beyond these optimum dates then grain yield decreases AND grain moisture increases in most years. Last year we had a wet spring that delayed planting on many acres, but we were fortunate to have a late warm fall that helped the corn make it to maturity and dry down some in the field. There is no telling what this fall will be like.
By May 15, corn yield is decreasing 0.5 bu/A per day delay accelerating to 2.5 bu/A per day delay on June 1.
Our area of the state has had limited opportunities to get some planting done, and there are still a lot of acres to go.
Joe Lauer, UW Extension Corn Specialist, provides the following information to help growers for making an informed decision on if and when they should switch maturities for corn hybrids.
Typically, the switch date for corn ranges between May 20-25. The switch date decision is also influenced by the eventual use of the corn. If the field to be planted is intended for corn silage or high moisture grain, then switch dates can be later because there is less concern about drying costs. The crop needs to achieve between 25% kernel milk for silage and black layer for high moisture corn grain yield to optimize yield. When farmers switch to new hybrids they should shorten relative maturity of hybrids to be planted by 7-10 days.
Another factor influencing switch date is, what shorter-season hybrids do you switch to? Is a good high-performing hybrid available from the seed company? Remember the basics as you select new hybrids and don’t be pressured into switching into just any hybrid – make sure it is a good performer.
In addition, switch dates are influenced by geographical location. There is more flexibility for southern Wisconsin than northern Wisconsin. In southern Wisconsin, we have two or more possible switch dates for grain, May 20-25 and June 1-5. While in northern Wisconsin, we have only one switch date May 20-25. If corn planting is delayed until June 1 in northern Wisconsin and June 15 in southern Wisconsin, then growers should consider putting corn planters away and planting soybeans. The low corn yields seen in June will not recover the input costs required to produce the crop. This decision is influenced by corn price, price of the alternative crop (usually soybean) and the proportion of farm acres of each crop left to be planted. If the production objective is dry grain and you have been delayed, then you may want to begin pricing fuel for fall drying.
One last point is that late-planted corn often has increased pest pressure, especially from European corn borer (ECB). Planting a transgenic Bt-CB hybrid can help manage ECB if pressure is high.
For more information in this topic readers can go to the following webpage Corn Late Planting at: https://tinyurl.com/yxuywlky
Some fields may not get planted due to excessive moisture this year. Paul Mitchell, UW Extension Ag Economist, has prepared a fact sheet addressing prevent plant considerations related to crop insurance for 2019, and that can be found at the following link: https://tinyurl.com/y5pv2wqg