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Soybean Scouting Calendar

The soybean scouting calendar provides tips for identifying soybean pests and insects as well as management considerations when scouting fields.* Additional information for most pests is available by clicking on the pest name.

Insect / DiseaseGrowing StageSymptoms
Bean Leaf Beetle

After Planting: 0-1 Month through Pod Fill to Leaf Drop

  • Leaf feeding from adults causes little impact unless defoliation exceeds 25%.
  • Pod feeding results in greatest damage and affects both quality and yield.
  • Adults also transmit bean pod mottle virus, which reduces both soybean quality and yield and also causes green stem and delays harvest.
Mexican Bean Beetle After Planting: 0-1 Month through Pod Fill to Leaf Drop
  • Larvae strip away the top layer of leaf tissue between the veins, giving the leaves a skeletonized appearance.
Phytopthora Root Rot After Planting: 0-1 Month through Pod Fill to Leaf Drop
  • Note dark brown lesion extending upward from soil line.
Bean Pod Mottle (BPMV) After Planting: 0-1 Month through Bloom to Pod Fill  
Pythium Root Rot After Planting: 0-1 Month
  • Soft decay of seed; missing seedlings in row.
  • Wilting, yellow leaves. Necrotic lesions on stems. Death of seedlings can occur quickly. Leaves remain attached to stem.
Two-Spotted Spider Mite

After Planting: 1 Month through Bloom to Pod Fill

  • Mites suck on the bottom sides of soybean leaves, removing plant moisture and nutrients, resulting in a yellow or whitish spotting on the top side of the leaf surface. In heavy infestations, it's common to see leaf burning and stippling.
  • Hot spots will typically be noticed first on field margins, as infested plants take on a wilted appearance. Drought-prone fields or field areas that contain lighter soils or sands are often affected first by spider mites.
Soybean Cyst Nematode

After Planting: 1-2 Months through Pod Fill to Leaf Drop

  • SCN can be scouted and observed visually on soybean roots at appropriate growth stages.
Rhizoctonia Root Rot After Planting: 1-2 Months through 2 Months to Max Height
  • Prefers cold soil temperatures (< 60 F); may be the first soybean disease found in a growing season.
  • High-residue fields and heavy or compacted soils are at higher risk because of cooler, wetter conditions.
Green Stink Bug

2 Months to Max. Height through Pod Fill to Leaf Drop

  • Prefer to feed on tender growth and developing seeds. Stink bugs feed by injecting digestive enzymes using a piercing sucking proboscis.
  • Feeding may cause delayed maturity, green stem and abnormal pods.
  • In cases of viral infections, hyaline bleeding such as with this soybean mosaic virus can occur.
Japanese Beetle 2 Months to Max. Height through Pod Fill to Leaf Drop
  • Skeletonized or lacy leaf patterns between veins are symptoms of either corn or soybean feeding.
  • Leaf feeding is typically insignificant in corn.
Soybean Aphid 2 Months to Max. Height through Bloom to Pod Fill
  • Shortened plant height.
  • Curled leaves, often yellow on outside (similar to potassium deficiency).
  • Excessive honeydew on leaves, which promotes sooty mold growth.
White Mold 2 Months to Max. Height through Bloom to Pod Fill
  • Infection begins with a water-soaked lesion originating at a node. If lesion stays wet, it can become overgrown with white mold
  • Sclerotia are dark, irregularly shaped bodies 1/4 to 3/4 inches long containing hardened mycelia.
Brown Stem Rot Bloom to Pod Fill through Pod Fill to Leaf Drop
  • Brown stem rot (BSR) infection causes vascular and pith tissues to turn brown to reddish brown.
  • Split stems longitudinally to inspect for brown stem rot.
  • Check at and between nodes near the soil line.
Sudden Death Syndrome Bloom to Pod Fill through Pod Fill to Leaf Drop
  • Splitting the root reveals cortical cells have turned a milky gray-brown color while the inner core, or pith, remains white.
  • General discoloration of the outer cortex can extend several nodes into the stem, but its pith also remains white.
Charcoal Rot Pod Fill to Leaf Drop
  • Symptoms usually begin during the reproductive stages of soybean development and are first evident in the driest areas of the field.
  • Earliest symptoms include smaller than normal leaves, reduced vigor, premature yellowing of top leaves and plants wilting during the midday heat.

*Scouting information based on information from DuPont Pioneer, Iowa State University Extension, Purdue University Extension, University of Illinois Extension and the University of Kentucky Extension.

These scouting times apply to soybeans grown in the Corn Belt. Scouting times in other geographies may vary. When pests appear in fields varies based on weather and other environmental conditions. The scouting dates shown are an approximation. Growers should routinely scout their crops and consult with a sales professional for more information.

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