Evaluating Corn Replanting Options

Cool temperatures and wet conditions have put stress on corn germination and emerging seedlings.  Before deciding to replant, some important steps should be taken:

1. Evaluate the stand for population and uniformity.
2. Compare yield potential of the existing stand with yield potential of the replant (consider insurance or government program restrictions).
3. If the decision is made to replant, consider various management practices discussed below to optimize yield potential.

Evaluating Existing Stands

When evaluating corn stands, only count plants that have a good chance of survival. Observe the uniformity of the stand across the field to determine whether the entire field will need replanting or if you can replant portions of the field.

There are a couple of options you can use when evaluating corn stands. (Please note the second option is a more accurate method).

1. Count the number of plants in a length of row equal to 1/1000^th of an acre based on row width (Table 1). Multiply the number of plants by 1,000 to get the plants per acre. Repeat the process in several field locations.
2. Count 150 plants and measure the distance from start to finish with a measuring wheel. Divide the number of feet traveled into the appropriate factor in Table 2 to determine plant population. For example, if you walked 94 feet while counting 150 plants in 30-inch rows, the population is 2,613,600÷94=27,804. Because a longer row length is counted, the samples are more representative and fewer locations are required.

Should I Replant?

After taking stand counts, consider yield potential of the current stand and planting date, compared to the yield potential of the target replanting stand and date, and the costs associated with replanting.

If you decide to replant …

The first step in deciding to replant is removing the existing stand. Tillage is an option in most cases, however, depending on the growth stage of the original stand, two passes may be necessary.

Second, determine which relative maturity (RM) to use when replanting. As planting occurs after May 1, corn requires approximately 1.6 fewer growing degree days (GDDs) per day of delayed planting to reach flowering.

Third, decide on a management practice to protect against corn rootworm and other soil insects, including European Corn Borer (ECB).

Finally, corn planted later in the season has a greater chance of exposure to heat and drought stress during pollination. Manage this risk by selecting a hybrid with heat and drought tolerance and early flowering.

If you have any questions about whether or not you should consider replanting, please don’t hesitate to let us know by commenting on this post, or by contacting us at 1-877-GO-LATHAM.

Source: Monsanto’s Agronomic Alert