moderate severity

Soybean Mosaic Virus DiseaseIdentification & Treatment Guide 2026

Q: How does SMV get into my seed?

SMV infects the developing seed through the mother plant. The virus moves from infected plant tissue into the seed coat and embryo. Seed transmission rates vary from 0-5% depending on soybean genotype, virus strain, and when the mother plant was infected. Early-infected plants produce higher rates of seed transmission.

Q: Can I tell if seed is SMV-infected before planting?

Seed coat mottling is associated with SMV but not a reliable indicator — some infected seeds look normal and some mottled seeds are not infected. The only reliable method is laboratory testing (ELISA or RT-PCR) of seed lots. Certified seed programs use these tests to ensure clean seed.

Q: Why don't insecticides control SMV effectively?

SMV is transmitted by aphids in a non-persistent manner — the aphid acquires and transmits the virus within seconds of probing a plant, before any insecticide can kill it. This is fundamentally different from persistent viruses (like BBTV) where insecticides have more time to kill the vector before transmission occurs.

Soybean mosaic virus (SMV) · Family: Potyviridae

Soybean mosaic virus (SMV) causes light and dark green mosaic mottling, leaf crinkling, stunting, and seed coat mottling. It is seed-transmitted (up to 5%) and spread by aphids. Manage by planting certified virus-free seed, using resistant varieties (Rsv genes), controlling aphids, and roguing infected plants early in the season.

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Quick Diagnosis

moderate

Soybean Mosaic Virus Disease

Affects: leavesseedspods
Peak Season: Throughout the growing season; aphid-mediated spread increases during warm, dry periods with high aphid flights
Spread Risk: Moderate
Spread By: Seed-borne (1-5% transmission), aphid vectors (non-persistent, >30 species), mechanical transmission

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Symptoms: What does Soybean Mosaic Virus Disease look like?

Visual identification guide — tap each stage for details

Green mosaic mottling on soybean trifoliate leaf from SMV — Light/dark green mosaic pattern on trifoliate leaves

Crinkled distorted soybean leaves from SMV — Leaf crinkling, rugosity, and narrowing from SMV infection

Brown seed coat mottling on soybean seeds from SMV — Seed coat mottling reducing seed quality and germination

Early Stage

Mosaic mottling on young trifoliate leaves
Alternating light green and dark green patches (mosaic) appear on young expanding trifoliate leaves. Leaves may be slightly cupped or wrinkled.

Mid Stage

Leaf distortion and stunting
Leaves become crinkled, rugose (blistered), and narrower than normal. Internodes shorten, causing stunted plants. Some strains cause severe leaf rolling.

Late Stage

Seed coat mottling and reduced seed quality
Seeds develop brown or black streaking of the hilum area and seed coat (seed coat mottling). Seed oil content decreases, germination is reduced, and seeds are prone to Phomopsis decay.

Causes: Why is my plant getting Soybean Mosaic Virus Disease?

Environmental triggers and disease cycle

Planting SMV-infected seed (primary inoculum source)
Aphid transmission from infected plants to healthy plants within and between fields
Mechanical transmission during cultivation or spraying
Volunteer soybean harboring virus

Disease Lifecycle

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Host Plant

Susceptible crop

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Pathogen

Potyvirus

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Conditions

Throughout the growing season; aphid-mediated spread increases during warm, dry periods with high aphid flights

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Infection

Penetrates tissue

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Symptoms

Visible signs

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Spread

Seed-borne (1-5% transmission)

Often confused with: Asian Soybean Rust, Bean Common Mosaic Virus Disease. See our comparison guide.

How to Treat Soybean Mosaic Virus Disease

Tick each step as you complete it — works offline too

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Organic Treatment Steps

4 steps

Plant certified virus-free seed tested to confirm <0.1% SMV infection rate.
Rogue symptomatic plants early (before V4 stage) to reduce in-field virus source for aphid spread.
Plant resistant varieties carrying Rsv1, Rsv3, or Rsv4 resistance genes.
Use reflective mulch or mineral oil sprays to deter aphid landing on high-value seed production fields.

🧪 ChemicalUse protective equipment

Chemical Treatment Steps

3 steps

Aphid-targeted insecticides have limited effectiveness against non-persistent virus transmission — aphids transmit before being killed.
Imidacloprid seed treatment provides early-season aphid suppression but does not eliminate virus transmission.
Mineral oil sprays (1-2% v/v) can reduce transmission by interfering with aphid stylet probing — most practical for seed multiplication fields.

Prevention & Seasonal Calendar

Year-round protection plan for your crops

Pre-Planting

Use certified virus-free seed — this is the most critical prevention measure
Plant SMV-resistant varieties where available

Mid-Season

Isolate seed production fields from commercial soybean
Remove volunteer soybean and infected plants early

Post-Harvest

Save seed only from disease-free fields

🛡️ Resistant Varieties

Varieties carrying Rsv1 (most common)Rsv3Rsv4Stacked Rsv1+Rsv3 for broad-spectrum resistance

View full seasonal calendar for your region →

Frequently Asked Questions

Common questions about Soybean Mosaic Virus Disease

How does SMV get into my seed?

SMV infects the developing seed through the mother plant. The virus moves from infected plant tissue into the seed coat and embryo. Seed transmission rates vary from 0-5% depending on soybean genotype, virus strain, and when the mother plant was infected. Early-infected plants produce higher rates of seed transmission.

Can I tell if seed is SMV-infected before planting?

Seed coat mottling is associated with SMV but not a reliable indicator — some infected seeds look normal and some mottled seeds are not infected. The only reliable method is laboratory testing (ELISA or RT-PCR) of seed lots. Certified seed programs use these tests to ensure clean seed.

Why don't insecticides control SMV effectively?

SMV is transmitted by aphids in a non-persistent manner — the aphid acquires and transmits the virus within seconds of probing a plant, before any insecticide can kill it. This is fundamentally different from persistent viruses (like BBTV) where insecticides have more time to kill the vector before transmission occurs.

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Related Disease

Asian Soybean Rust

Phakopsora pachyrhizi

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Related Disease

Bean Common Mosaic Virus Disease

Bean common mosaic virus (BCMV)

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Affected Plant

Soybean

Glycine max

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Treatment Guide

Full Treatment Protocol

Detailed spray schedule & dosage guide

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