The last thing you want to think about this time of year is replanting. The unfortunate reality is some farmers will face the possibility due to a host of causes. Consider the logistics now so you’re prepared if replant is inevitable.
“Before you replant, figure out what caused the problem in the first place and solve it so you don’t deal with that same problem again,” says Steve Hoffman, president and managing agronomist for InDepth Agronomy. Doing this will set up new stands for greater success.
“Wait five days after the event that caused the issue to assess your stand to determine what percent of the crop may recover,” advises Jared Webb, DeKalb agronomist.
Determine the extent of replant and if terminating the original crop is necessary. It’s likely more economically and agronomically sound to replant the areas with severe damage—not the entire field. So you’ll need to scout thoroughly to identify those spots.
“Once you determine what area or areas you’re going to replant, know that with corn it’s better to take out the previous stand,” Hoffman says. “Soybeans, on the other hand, have good success if you need to patch in and thicken up stands.
Soybeans can compensate by bushing out and putting on more pods. If corn is interseeded into an already-growing stand the smaller plants can’t compete with the older plants. This causes the smaller plants to underperform and steal yield potential from the larger plants. Consider tillage or herbicides to destroy old corn stands.
- “Tillage is most effective if the surviving plants are emerged,” says Brent Tharp, Wyffels Hybrids agronomy and product training manager. “You need to work it deep, at least 3" at an angle, to tear out the plants.”
- Know your options with herbicides. “There are some herbicides that you can plant back right away, but others you need to wait five to seven days,” Webb says. Consider the trait stack you used as its herbicide tolerances could limit your options for terminating the original stand. Carefully read herbicide labels to make sure you can replant in a timely manner after any restrictions.
Figure out if you can plant the same seed, if you need to shorten maturity or if you need to switch crops altogether. For this decision, timing is everything.
“Corn can adjust its relative maturity, which means late planted corn requires fewer growing degree days to reach physiological maturity,” Tharp says. “We advise farmers to keep their original hybrid until the very end of May.”
If you’re replanting sections of a field and want to change maturity so the entire field dries at the same time, Tharp says a five-day difference is typically the lowest you’ll need to go. “Don’t go from a 110-day hybrid to a 98-day hybrid; stick with what’s adapted to your area,” he adds.
Soybeans rely on length of day and again are flexible and responsive when replanted. In some cases, you might need to shorten maturity, but not by more than five days.
If you’re considering switching to a different crop, such as to soybeans after a hail storm in late June destroys your corn stand, make sure the next crop is feasible.
“Be mindful of what herbicide you used, which might dictate what crop you can actually plant,” Webb says. For example, if you use certain broadleaf herbicides you can’t switch from corn to soybeans.
Switching crops isn’t common because herbicides, insecticides and other inputs are tailored for the original crop, therefore it’s typically more cost effective to replant the same crop.
Consider all costs when you update your budget. Some replant costs are obvious: seed, fuel, fertilizer, labor and burndown herbicides, but others might sneak up on you.
“Don’t forget the cost of removing the original stand and added drying time,” Tharp advises.
Because your crops will canopy later in the season, weeds such as waterhemp could be more aggressive. This could mean you need to apply an extra herbicide pass.
You might need additional or new insecticides, too. “In corn, if you first used a soil-applied insecticide and tilled to terminate the original stand, you’ll have to reapply or use a Bt hybrid,” Hoffman says. “If you kill off the old stand with a herbicide and plant directly into the old rows you might be able to avoid reapplying insecticide.”
When you must replant there are a number of factors working against you. Use this information and work with your input suppliers to make any replant areas yield as high as possible while keeping an eye on added costs.
Use this plant-back interval information to plan herbicide passes.
