| Pest
Species |
Abbreviation |
Economic Thresholds |
Bean Leaf Beetle
Ceratoma trifurcata |
(BLB) |
Seedlings
- 20% of the plants are cut and the stand has gaps of 1 foot or more; or if
at least 1 seedling per foot of row is destroyed.
Before Bloom - 30% of leaf area removed and there are 5 or more beetles per
foot of row.
Bloom to Pod Fill - 20% of leaf area removed and there are 16 or more
beetles per foot of row.
Seed Maturation - 5 to 10% of the pods are damaged, the leaves are green,
and there are 10 or more beetles per foot of row. |
Red-legged
Grasshoppers
Melanoplus femurrubrum
Differential Grasshopper
Melanoplus differentialis |
(GH) |
20 or more
grasshoppers per square yard in the field margins prior to their migration into soybeans.
Alternative thresholds - 30% of leaf area removed before bloom or 20%
between bloom and pod fill, when 5 to 10% of the pods are damaged. |
Green Cloverworm
Plathypena scabra |
(GCW) |
12 half grown larvae
or more per foot of row and 20% of leaf area removed.
Note: If disease and parasitism levels are high, the population will be
controlled without the use of an insecticide. |
Japanese Beetle
Popillia japonica |
(JB) |
20% of leaf area
removed during bloom and pod fill. |
Cabbage Looper
Tricoplusia ni
Soybean Looper
Pseudoplusia includens |
(CL) |
30% of leaf area
removed before bloom and 20% of leaf area removed after bloom. |
Mexican Bean Beetle
Epilachna varivestis |
(MBB) |
30% of leaf area
removed before bloom and 20% of leaf area removed after bloom. |
Potato Leafhopper
Empoasca fabae |
(PLH) |
V1 - 1 PLH per plant
V2 - 3 PLH per plant
V3 - 6 PLH per plant
R4 - 9 PLH per plant
R5 - 12 PLH per plant
R6 - 15 PLH per plant
R7 - 18 PLH per plant
Alternative thresholds - 4 per sweep if plants are moisture stressed; 8 per sweep
if plants are not under stress. |
Seed Corn Maggot
Delia platura |
(SCM) |
None established.
Rescue treatments are not effective. Therefore, a seed treatment may be advisable in
fields with a history of problems or where organic matter is decaying at the time of
planting. |
Stinkbug (Brown)
Several species
Stinkbug (Green)
Acrosternum hilare |
(STB) |
When adults and/or
nymphs reach one or more per foot of row during pod fill. |
Soybean Thrips
Sericothrips variabilis |
(STP) |
None is established.
Treatment is not usually justified. However, 25 or more thrips per leaflet may cause some
mottled leaves. If it appears seedlings are being seriously damaged and some are dying,
treatment may be justified. |
Two-spotted Spider
Mite
Tetranychus urticae |
(TSSM) |
Treatment is usually
justified when plants along field margins are showing leaf discoloration and mites are
present. |
| The economic thresholds were found in the "Field Crop Scouting
Manual" of the University of Illinios Cooperative Extension Service. |
