When to switch corn hybrids in a wet spring

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Wet spring conditions across Ontario have some corn growers contemplating whether it’s time to switch hybrids and plant shorter season corn hybrids.

In Eastern Ontario, Pioneer Seeds Canada agronomist Paul Hermans is one of many agronomists fielding calls from growers looking for insight on when to make a swap. Planting progress varies from 15 percent in eastern areas of the province and Quebec, to up to 40 per cent in parts of Southwestern Ontario.

It’s an emotional time for many growers as they struggle with wet planting conditions, says Hermans, who acknowledges that frequent rains have prevented some farmers from turning a wheel. But as the calendar turns past the middle of May, growers on rain-soaked and heavier soils in shorter-season areas are looking at their options.

In these areas, Hermans says it’s important to look at data as well as recommended switch dates. Based on available hybrid research, Hermans is recommending growers “hold the line until May 20th to the 25th with what you are currently growing” for the eastern portion of the province.

Provincial research trials indicate corn still maintains 95 per cent of its yield potential when planted as late as May 25th in much of Ontario. Switching to shorter-season hybrids is not recommended until May 15 to May 20 in areas less than 2800 CHU, May 20 to May 25 in areas 2800 to 3200 CHU; and May 30th to early June in areas over 3200 CHU. General recommendations are to reduce hybrids 100 CHU for every week after these dates that planting is delayed.

In this interview with RealAg Radio host Lyndsey Smith, Hermans says farmers also need to consider their risk profile and the acres they need to cover when making switching decisions. (Story continues below the player)

How much of a yield reduction could growers take when switching to shorter season corn? Hermans says any good agronomist will tell you that depends on a number factors, including the hybrid and the reduction in heat units. He pegs the yield hit in dropping from 2800 CHU to 2700 CHU in the five to eight bushel range.

While growers may lose some bushels on the heat unit drop, Hermans is stressing patience and how sitting tight can pay yield dividends at season’s end. He notes that data shows growers gain only two to five per cent yield when they hit their optimum timing window for planting; they stand to gain five to 10 per cent, however, when plants emerge evenly.

“I would rather make sure that we’re doing a good job, have good emergence, and don’t mud it in,” says Hermans. “I can lose a lot more that way than I can by reducing my corn heat units units.”

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