Table 2. Estimates of percent yield loss in corn due to leaf defoliation at selectedd leaf stages
Leaf stage (/a)
Percent leaf defoliation
10,000
12,000
14,000
16,000
Approximate % yield loss
7-leaf
0
2
5
9
8-leaf
0
3
6
11
9-leaf
1
4
7
13
10-leaf
1
6
9
16
11-leaf
1
7
12
22
12-leaf
2
9
16
28
13-leaf
2
10
19
34
14-leaf
3
13
25
44

(/a) Leaf stage according to the "droopy leaf" method (see Nielsen, 2004a). The corresponding leaf stage according to the leaf collar method would be approximately 2 less than the "droopy leaf" values shown above (e.g., 7-leaf ~ V5)

Adapted from the National Crop Insurance Association's "Corn Loss Instruction" (Rev. 1994).