“One major concern is that, as we saw in 2005, plants that suffered freeze damage at about the V3 stage may not produce as much yield as undamaged plants even if they recover green leaf area. Physiological damage, coupled with the current slow growth of roots and tops due to loss of leaf area, may irreparably decrease plants’ productive potential. Plants from the March 29 planting are already approaching the size of the less-damaged plants from the March 16 planting, and I expect the later planting to yield more per plant than the earlier one.”
One of the keys to good yield is an even stand which does not have some plants that will rob others of moisture and nutrients. But after the frost, uneven stands may be prevalent, because root growth will be at different rates.
Nafziger directs your attention to a table he has published in the corn chapter of the Illinois Agronomy Handbook. In table 2.3 on page 24 he evaluates planting date with final plant population to determine the percent of maximum yield. Yield reaches its maximum yield if planted on April 10 with a 35 to 40 thousand population. It can also be achieved on April 20 with a 35 thousand population.
He says, “For example, corn planted at 35,000 per acre on April 25 with its plant stand reduced to 15,000 by cutworm injury would be expected to yield 71% of a normal stand. If such a field were replanted on May 19 to establish 35,000 plants per acre, the expected yield would be 86% of normal. Whether it would pay to replant such a field depends on whether the yield increase of 15 percentage points would repay the costs to replant. In this example, if replanting is delayed until early June, the yield increase to be gained from replanting disappears.”
Frost damaged corn will have a variable survival rate, but some survivors will be unable to make much progress. Determining the population of viable plants and the date of any replanting will help make a replanting decision, since cost of new seed will be a significant issue.
Source: FarmGate blog