Making replant decision locally


Tony Nye - OSU Extension



The weather finally allowed our farming community to have a somewhat successful week of planting both corn and soybeans.

There is still lot’s to get done to finish this year’s planting season. As I am writing this week’s column, it is threatening to rain (Thursday morning). I am hopeful it misses or drops very little so we can get through to Sunday before it looks like rain for sure.

As farmers progress with planting I hear more and more issues with fields that were planted before the heavy rains a few weeks ago. Poor stands are the result of a combination of many factors that include of course excessive moisture, freezing temperatures and frosts, fungal seed decay, seedling rots, soil crusting as well as other issues.

The obvious is to evaluate each stand to determine whether replant is necessary or not. There are a few things to consider in making that decision which include strong evidence that the returns to replanting will not only cover replant costs but also net enough to make it worth the effort. Don’t make a final assessment on the extent of damage and stand loss too quickly. The following are some guidelines provided by OSU agronomists to consider when making a replant decision:

If the crop damage assessment indicates that a replant decision is called for, some specific information will be needed, including:

• Original target plant population/Intended plant stand

• Plant stand after damage

• Uniformity of plant stand after damage

• Original planting date

• Possible replanting date

• Likely replanting pest control and seed costs

To assess the field you will need to make several counts in different rows in different parts of the field. Six to eight counts per 20 acres is generally plenty.

A major consideration in making a replant decision is the potential yield at the new planting date and possibly different planting rate: this can vary depending on the hybrid used, soil fertility and moisture availability.

For instance, If we originally planted around April 26 and targeted a 30,000 final plant count, some research says that is about the right date to get optimum yield.

If we cut that population to 20,000 and do nothing to replant that field, at best it has a yield potential of 92% of original optimum yield. If we decide to replant on May 20 and target again a 30,000 final plant population it too if all goes right, it can potentially yield 91% of April 26 optimum yield.

If we get to the end of May, that potential drops to 81%.

It’s also important to note plant distribution within the row. Remember that values in replant charts are based on a uniform distribution of plants within the row. Add a 5% yield loss penalty if the field assessment reveals several gaps of 4 to 6 feet within rows and a 2% penalty for gaps of 1 to 3 feet.

Yield loss due to stand reduction results not only from the outright loss of plants but also from an uneven distribution of the remaining ones.

OSU agronomists suggest that the more numerous and longer the gaps between plants within the row, the greater the yield reduction. It’s also important to consider the condition of the existing corn.

When making the replant decision, OSU agronomists recommend considering seed and pest control costs. As for the correct hybrid maturity to use in a late planting situation, continue to use adapted hybrids switching to early/mid maturities, if necessary, depending on your location in Ohio.

You also need to review herbicide and insecticide programs under late‑planting conditions. For instance, it may be necessary to reapply herbicides, especially if deep tillage is used. However, try to avoid such tillage depending instead on postemergence chemicals or cultivation for weed control.

When considering insect control, if soil insecticides were applied in the row at initial planting, check insecticide label restrictions before re‑application. Also remember that later May and early June planting dates increase the possibility of damage from European corn borer and western bean cutworm so planting Bt hybrids that effectively target these pests is often beneficial

The cost of replanting will differ depending on the need for tillage and chemical application. The cost and availability of acceptable seed will also be considerations. These factors must be weighed against expected replanting yield gains.

A decision for many that is hard is if after considering all the factors, there is still doubt as to whether or not a field should be replanted, you will perhaps be correct more often if the field is left as is. Another piece to consider is your crop insurance coverage. How will your insurance coverage play into your decision to replant or not?

Not an easy decision to make but one that is necessary in a year like this. Many experienced farmers have been down this path before and will know what the right decision is for their operation.

Hope for continued good weather so our farm families can get this crop in the ground and can start looking forward to a bountiful harvest this fall.

Tony Nye is the state coordinator for the Ohio State University Extension Small Farm Program and has been an OSU Extension Educator for agriculture and natural resources for 29 years, currently serving Clinton County and the Miami Valley EERA.

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Tony Nye

OSU Extension