Diagnostic Tools

Scouting Guidelines

Diseases and insects show up at different, often predictable times during the growing season.

In general, scouting for insects is based on the time of the year and crop development stage, while scouting for diseases is based mainly on the crop development stage.

Disease / Pest Growth stage to scout Best time to scout Best place to scout

Soybean Aphid 
Also look for ants and ladybird beetles.

V1-2 . Scout two times per week during this time period. Continue scouting through pod set. In early July, start scouting to become familiar with the aphid pressure in your fields. Use a hand lens or other magnifier. V1-2: Under young upper leaves, petioles, and stem.  
Vn: new branches in the lower canopy.  
R1-R4: undersides of mid-canopy leaves and stems.

Bean leaf beetle

First-generation peak in late V or early R stage. Second-generation peak during pod-fill stage. Early July (first generation) August (second generation).

Bean pod mottle virus

maturity at harvest check seed

Brown stem rot

full pod late August not specific

Phytophthora root or stem rot

vegetative stages July and August Wet and waterlogged soils. Compacted soil.

Seedling blight Pythium or Fusarium

before V2 late May or when soil temperatures are cold (<60°F) low and wet spots

Seedling blight Phytophthora or Rhizoctonia

before V2
(late planted)
mid-June or when soil temperatures warm to 70-80°F. low and wet spots

Soybean Cyst Nematode

6 weeks after planting up until 3 to 4 weeks before harvest. Easier to observe on soybean roots early in the season. A suspect area: a field entrance, areas that had flooded, weedy areas, lower yielding areas.

Soybean mosaic virus

maturity at harvest check seed

Spider Mites

any stage July and August, especially during periods of drought plants near the edges of the fields or where soybeans are stressed

Stem borer

late V, early R mid-summer Individual wilted or dying leaves in the middle of the canopy.
Later in the season, look for lodged plants.

Sudden death syndrome

pod setting after mid-August high-moisture areas in fertile fields

White mold mushroom (apothecia)

at canopy closure last week of June,
1st week of July,
varies with row spacing
high soil moisture areas, especially during flowering.
Areas where moisture collects due to fogs, extended dew periods and pockets of poor air drainage.

White-mold– infested plants

pod setting August-September visibly dead plants

Soybean viruses

maturity at harvest check seed