Look to stand count first, uniformity second

Replanting decisions should be based on stand numbers and yield potential

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As cold rain and snow fell in mid-May, Ontario farmers wondered whether early-planted grains could endure.

Fortunately, it appears most have. But where replanting might be required, agronomists say it’s overall numbers that matter first.

Why it matters: When determining whether replanting is necessary, calculate stand count first. Look at uniformity afterwards, as well as what’s actually causing stand gaps.

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An east-west rundown

“Ninety-five per cent of the corn is in the ground in southwestern Ontario. Most of it is in really good shape,” says Bob Thirlwall, market development agronomist with Bayer Canada, based in Glencoe.

With a substantial number of corn acres planted before and during May’s cold precipitation events, says Thirlwall, initial replant estimates were much higher — particularly for those working heavier, crusting-prone soils. However, timely showers in the last two weeks of the month helped alleviate some concerns.

“We are replanting corn a lot less than we were originally concerned about,” he says, adding that there is a fair amount of ongoing “crust busting” work.

Even in cases of uneven emergence – caused by too much cold moisture hitting the seed bed — most farmers were able to achieve a good stand.

Conditions in Eastern Ontario are similar. Clare Kinlin, certified crop advisor with MacEwen Ag, says corn replanting has been largely confined to “touch-up” work. However, stand reductions of 10 to 12 per cent are not uncommon, due in part to crusting issues.

“It’s more than adequate to get good corn yields,” says Kinlin.

Soybeans are a more complicated story. Fields planted near the beginning of May require additional seeding, though most planting did not occur so early.

“Some very early planted beans are at 40,000 to 50,000 plants. We are going to thicken them up, maybe drill-in another 50,000,” Kinlin says.

He adds the spring wheat planting went well overall but forages did not fare well.

“The forage crop is terrible. We had fall rye heading-out at eight inches tall when it’s normally four feet.”

Is a replant necessary?

Determining whether a replant is necessary starts with determining stand count and uniformity.

In corn, Thirlwall says a good minimum to consider is 22,000 plants per acre.

“Once you’re at 15, 000, it’s time to replant. Stand count is definitely the most important thing,” he says.

In the east, Kinlin lists 18,000 plants as the threshold at which replanting should be considered.

Both Thirlwall and Kinlin reiterate uneven stands can also be an issue if the differences are severe enough. Making the call to replant based off gaps alone, though, is more difficult since the issues could have been caused by a variety of environmental and management-related causes (e.g. a poor planter setup).

“Take the emotions out of it and just look at the numbers,” says Kinlin. “Look at yield potential, why it didn’t come up, and make those decisions on an individual basis.”

Is the ground ready?

Whether the ground is ready for planting is critical in early spring. Thirlwall says soil temperature should ideally sit at five to eight degrees Celsius, with an ideal planting depth of one and three-quarter to two inches for most soils (planting depth can be deeper in sand, however).

He also reminds growers to keep an eye on the sky.

“You don’t want the first moisture that corn soaks up to be cold rain.”

Kinlin reflects a similar sentiment.

“That’s the importance of having a good seed bed. Where people thought the ground was ready to no-till beans, it really wasn’t. It was still cold and wet underneath. The high-level residue seems to have kept things down,” he says.

Regardless, both agronomists reiterate modern genetics and seed treatments are much more effective than older technologies at helping seeds withstand stress.

“Seed treatments hide a lot of mistakes,” Kinlin says.

About the author


Matt McIntosh

Matt is a freelance writer based between Essex County and Chatham-Kent. He is interested in all things scientific, as well as rock n' roll, hunting and history. He also works with his parents on their sixth-generation family farm.



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