Think you need to replant corn?
Corn planted early this spring faced something of a tough go getting started because of cool, wet weather that lasted a lot longer than normal. And since then, storms have raked through parts of corn country, leaving hail or wind damage. If you've got corn in either category, you may be facing a dilemma of whether or not to replant. And, this year, that's an even tougher decision to make because of the shortened window of decent planting conditions.
Start with a stand evaluation, through which you can find out both the stand you have remaining and whether or not that stand's been injured to the point of lower yield potential.
"To determine a plant stand for row crops, take several sample counts to represent the field or area under consideration. For ease of calculation, a sample size of 1/1000 acre is recommended. Measure off the distance appropriate for your row width, count the number of live plants, and multiply by 1,000 to obtain a reasonable estimate of plants/acre," according to a report from DuPont Pioneer. "Stand counts should be taken randomly across the entire area of the field being considered for replant; this may include the entire field or a limited area where damage occurred. The accuracy of your stand estimate will improve with the number of locations sampled within the damaged area."
Once you've taken a stand assessment, there are a couple of key things to consider for the stand you do have: First, what's the health of the remaining plants? How about the uniformity of those plants?
"Plants that survive but are severely injured or defoliated will have reduced photosynthetic capability and a lower yield potential," according to Pioneer. "Consider whether surviving plants are evenly distributed in the field or if the stand is uneven, with frequent long gaps in the rows. An uneven stand will yield less than a relatively even stand with the same number of plants."
Now, take that information and compare it with optimal planting dates for your area, when you planted, and what percentage of full yield potential remains in your crop based solely on those variables. Compare that with the results from what you gleaned from a stand assessment about your existing yield potential. Then, don't forget other variables to consider before you finally decide whether or not to replant.
"Even if replanting will increase yield, the yield increase must be sufficient to pay for all of the costs associated with replant such as: Extra herbicide or tillage costs (fuel, labor, equipment) to remove the old stand and prepare the new seedbed; planting costs (fuel, labor, seed, equipment); and increased grain drying costs," according to a Pioneer report. "Also consider these factors when making a replant decision: Probability of an autumn freeze prior to physiological maturity of replanted corn; and increased susceptibility of late-planted corn to summer drought or disease and insect pests such as gray leaf spot and European corn borer."