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Replanting Decisions
Ten
to 15% of your seed typically fails to
become healthy plants due to insects,
frost, hail, flooding, or poor seedbed
conditions. Before replanting do not
make a quick decision. Corn plants often
outgrow leaf damage, especially when the
growing point is below ground. If new
leaf growth appears within a few days
after the injury, the plant is likely to
produce normal yields.
When deciding to replant, consider:
-
Original planting date and plant
stand (target population).
-
Present plant population.
-
possible replanting date and plant
stand (target population).
-
Cost of seed, machinery, labor, fuel
and pest control for replanting
versus the yield increase.
As a general guideline, yields will be
reduced an additional 5% if there are
gaps for four to six feet in the row and
2% for gaps of one to three feet.
Example:
A field at the optimum planting date
with a 25,000 plant population would
achieve 98% of maximum yield. If the
stand was reduced to 15,000, the corn
would achieve 82% of maximum
yield. This is a 16% loss due to stand
reduction. If the earliest replant date
is 20 days later with a final population
of 25,000 yield prospects would be 89%
of maximum. This is a 7% gain in
replanting over leaving the older,
reduced stand. If gaps of one to three
feet where present, there would be a 9%
gain in replanting. Will a 7 or 9%
increase in yield pay for replanting
costs?
% of Maximum Yield by Plant Population
|
Date |
10,000 |
15,000 |
20,000 |
25,000 |
30,000 |
35,000 |
|
20
days early |
62 |
76 |
86 |
92 |
94 |
93 |
|
10
days early |
67 |
81 |
91 |
97 |
99 |
97 |
|
Optimum |
68 |
82 |
92 |
98 |
100 |
98 |
|
10
days late |
65 |
79 |
89 |
95 |
97 |
96 |
|
20
days late |
59 |
73 |
83 |
89 |
91 |
89 |
|
30
days late |
49 |
63 |
73 |
79 |
81 |
79 |
Source: University of Illinois (adapted)
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