ESTIMATED % CORN GRAIN YIELD LOSS DUE TO DEFOLIATION AT VARIOUS GROWTH STAGES1

% Leaf Defoliation
10 20 30 40 50 60 70 80 90 100
Growth Stage2 % Yield Loss
7 leaf 0 0 0 1 2 4 5 6 8 9
9 leaf 0 0 1 2 4 6 7 9 11 13
11 leaf 0 1 2 5 7 9 11 14 18 22
13 leaf 0 1 3 6 10 13 17 22 28 34
15 leaf 1 2 5 9 15 20 26 34 42 51
17 leaf 2 4 7 13 21 28 37 48 59 72
19-21 leaf 3 6 11 18 27 38 51 64 79 96
Tassel 3 7 13 21 31 42 55 68 83 100
Silked 3 7 12 20 29 39 51 65 80 97
Silks Brown 2 6 11 18 27 36 47 60 74 90
Blister 2 5 10 16 22 30 39 50 60 73
Milk 1 3 7 12 18 24 32 41 49 59
Soft Dough 1 2 4 8 12 17 23 29 35 41
Early Dent 0 1 2 5 9 13 18 23 27 32
Late Dent 0 0 1 3 5 7 9 11 13 15
Mature 0 0 0 0 0 0 0 0 0 0

1 Adapted from the National Crop Insurance Service's "Corn Loss Instruction" (Rev. 1984)

2 As determined by counting fully expanded leaves (i.e., those with 40-50% of leaf exposed from whorl and whose tip points below the horizontal.)

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Corn, Soybean, Wheat, and Alfalfa Field GuideBulletin 827