Common Soybean Diseases—And How to Fight Them
Learn about the various seed- and soil-borne diseases that can affect the health of your crop—and how to keep your crop protected.
PYTHIUM & PHYTOPHTHORA
What it does:
Attacks soybean crops and is responsible for damping off, seed rot, seedling rot and root rot.
Has the ability to “swim” in wet soil, therefore can spread easily.
Disease severity increases when crop is grown for more than 2 consecutive years, or grown in cool, wet soils
Decreases germination and emergence of seeds and seedlings
Results in poor stands
What it looks like:
Water-soaked lesions on the roots/leaves. Also possible are brown stem lesions and white powdery areas on stems.
How to prevent it:
Anchor™ (Mefenoxam®) Fungicide
Azoxystrobin Fungicide
T-Methyl (Thiophanate-Methyl) Fungicide
N-Compass AZO Fungicide/Insecticide Seed Treatment Blend
N-Compass Plus Fungicide/Insecticide Seed Treatment Blend
RHIZOCTONIA
What it does:
Fungal pathogen that can kill and stunt plants to result in significant yield losses.
Root and stem rot primarily occurs in early to mid summer.
Infected plants typically appear in patches in a row or field.
Common in moist (but not saturated) soil conditions
Common in warm temperatures (80 degrees)
What it looks like:
Localized reddish-brown lesions in the cortical layer of the main root. Wilting symptoms in dry-soil conditions.
How to prevent it:
Azoxystrobin Fungicide
Thiabendazole Fungicide
T-Methyl (Thiophanate-Methyl) Fungicide
Fludioxonil Fungicide
SUDDEN DEATH & FUSARIUM
What it does:
Attacks plants in 2 ways: a root rot phase and a leaf scorch phase.
Infects soybean roots shortly after germination.
Infection is greater when seedling development is slowed by cool, wet soil conditions.
During late vegetative or early reproductive stages, SDS produces a toxin that moves up through the plant to the leaves, where it produces the associated foliar symptoms.
Can survive in soil for several years.
What it looks like:
Substantial root discoloration, root rot and crown rot.
When split with a knife, roots tissue will appear gray to reddish brown.
Small, pale-green to yellow circular spots on the leaves.
As the disease progresses, the areas between the leaf veins will turn bright yellow, and then brown, with the veins remaining green.
The leaves will detach from the petioles and fall.
How to prevent it:
WHITE MOLD (SCLEROTIUM)
What it does:
Causes yield loss in soybeans due to decreased pod fill and seed contamination.
Thrives in cool, wet weather.
Initial infection occurs during the flowering period.
Can survive in soil for several years.
What it looks like:
Water-soaked lesions on stems, bleached stems, wilting, lodging.
White cottony growth.
Black rock-like structures.
Often occurs in patches in the field.
How to prevent it:
Azoxystrobin Fungicide
Thiabendazole Fungicide
T-Methyl (Thiophanate-Methyl) Fungicide
PHOMOPSIS
What it does:
Pod and stem blight that damages and decays seeds, leaving them white, black, chalky and shriveled.
The disease can plague germination rates during planting season.
What it looks like:
White, black, chalky and shriveled seed pods.