Widespread late-May frosts across Ontario have many growers assessing soybean crops for injury and wrestling with the question of whether replanting is necessary.
On this episode of the Soybean School, Ontario Ministry of Agriculture, Food and Rural Affairs soybean specialist Horst Bohner is preaching patience when it comes to determining whether a replant is necessary. He notes that even when the cotyledons have been frozen off, if the growing point has been protected, new growth will emerge.
Bohner also recommends growers keep an eye on the number of plants that have yet to fully emerge. “When we get into a scenario where it’s obvious there’s been frost… we can make the decision too quickly to condemn a field because some plants are still emerging.” He notes soybeans that are not totally out of the ground can handle more frost than those that have emerged and are completely exposed.
Bohner says growers need to wait five or even seven days to see if there’s new growth. He adds that the vast majority of these plants will yield just as well as soybeans that haven’t had a frost.
Growers should consider replants when plant populations fall below 90,000 per acre, or a little higher on heavy clay soils. Row spacing is also a consideration. “If it’s a nice consistent even stand in 30-inch rows you could probably go as low as 70,000 plants. But in that range we’re going to have to thicken things up or start over with a full seeding rate,” adds Bohner.
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