Field Crop Diseases
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Soybean Mosaic

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Symptoms:
Soybean mosaic causes stunting of plants and crinkled and mottling of leaves.
Infected plants range from no symptoms to severely mottled and deformed.
The leaf blades are puckered along the veins and curled downward.
The mottling appears as light and dark green patches on individual leaves.
Symptoms can be difficult to see when temperatures are above 90°F.
Do not confuse with growth regulator herbicide damage where the leaves will be elongated and which usually occurs in a pattern such as along a field edge.
Soybean mosaic can also reduce seed size and pod number per plant, and soybean mosaic is one of several factors associated with discoloration of seeds, causing a dark discolored tear stain origination at the hilum.
The virus can interact with bean pod mottle virus (BPMV) to create severe symptoms in plants infected with both viruses.

Pathogen Involved:
Soybean mosaic virus (SMV). This virus has a wide host range including pea and snap bean.
SMV is transmitted by aphids and infected seed.

Time of Occurrence:
All season.

Conditions Favoring Disease:
Plants infected when young tend to show more symptoms than plants that infected when older.
Higher activity or populations of aphids favor virus transmission.

Disease Management:
Plant seeds free of SMV. Plant early.

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