TREATMENT THRESHOLDS FOR INSECT DEFOLIATED SOYBEANS
PERCENTAGE DEFOLIATION*
Soybean
growth
stage
Market price-$5/bu
Cost of treatment
Market price-$6/bu
Cost of treatment
$6/A
$8/A
$10/A
$12/A
$14/A
$6/A
$8/A
$10/A
$12/A
$14/A
V1-2
40-50
45-55
50-60
45-55
55-65
35-45
40-50
45-55
45-55
50-60
V3-4
40-50
45-55
50-60
55-65
55-65
40-50
45-55
45-55
50-60
50-60
V5-6
45-55
45-55
50-60
55-5
55-65
40-50
45-55
50-60
50-60
50-60
V7+
40-50
40-50
45-55
50-60
55-65
35-45
40-50
40-50
45-55
50-60
R1
25-35
30-40
35-45
40-50
40-50
25-35
25-35
30-40
30-40
35-45
R2
20-30
25-35
30-40
35-45
35-45
20-30
25-35
25-35
25-35
30-40
R3
15-25
20-30
20-30
25-35
25-35
10-20
15-25
20-30
20-30
20-30
R4
10-20
15-25
15-25
20-30
20-30
10-20
10-20
15-25
15-25
20-30
R5
15-25
15-25
20-30
20-30
25-35
10-20
15-25
15-25
15-25
20-30
R6
15-25
20-30
25-35
25-35
30-40
10-20
20-30
25-35
25-35
30-40
PERCENTAGE DEFOLIATION*
Soybean growth
stage
Market price-$7/bu
Cost of treatment
Market price-$8/bu
Cost of treatment
$6/A
$8/A
$10/A
$12/A
$14/A
$6/A
$8/A
$10/A
$12/A
$14/A
V1-2
35-45
40-50
40-50
40-50
45-55
30-40
35-45
40-50
40-50
45-55
V3-4
35-45
40-50
45-55
45-55
45-55
35-45
40-50
40-50
40-50
45-55
V5-6
40-50
45-55
45-55
45-55
50-60
40-50
40-50
45-55
5-55
45-55
V7+
35-45
35-45
40-50
40-50
45-55
35-45
35-45
40-50
40-50
45-55
R1
20-30
25-35
30-40
30-40
30-40
20-30
25-35
25-35
30-40
30-40
R2
15-25
20-30
25-35
25-35
25-35
15-25
20-30
20-30
25-35
25-35
R3
10-20
15-25
15-25
15-25
20-30
10-20
15-25
15-25
15-25
20-30
R4
10-20
10-20
10-20
15-25
15-25
5-15
10-20
10-20
15-25
15-25
R5
10-20
10-20
15-25
15-25
20-30
10-20
10-20
15-25
15-25
15-25
R6
15-25
15-25
20-30
20-30
25-35
10-20
15-25
20-30
20-30
20-30
The defoliation level needed before a control is applied will vary somewhat depending on insect numbers and stage of development, growing conditions, variety grown, expected yield, economic factors, and plant population counts. All of these factors must be taken into consideration when making control decisions. The defoliation figures are shown as a range in each category. This range is included so that limiting factors can be considered. When few limiting factors are present, the control decision value will normally be at the higher end of he scale. Under some circumstances or conditions management guidelines given above may need to be adjusted from what is given. Based on 50 bushel per acre yield.