Soybean Viruses - Scouting

To determine if a virus problem exists in your field, look for the following signs:

• Moderate to high insect activity
• Presence of leaf symptoms: mottled, crinkled leaf symptoms typical of virus infection.  Foliar symptoms of virus infection will be most apparent during times of rapid growth and cooler weather.
• Lower than expected yields
• Mottled seed
• Green stem plants at harvest maturity

Be aware that leaf symptoms are not a consistent indicator of virus infection. Soybean varieties differ in the amount of leaf symptoms that develop. Climatic conditions and growth stage can also mask leaf symptoms. Mottled and crinkled leaves can have other causes, such as herbicide injury or nutrient deficiencies.

Seed coat mottling as a symptoms of virus infection

Check seed at maturity for signs of discoloration and mottling. Seed infected with SMV and other viruses are often discolored.

Unfortunately, seed mottling is not a reliable indicator of SMV or BPMV infection because some varieties develop seed mottling when infected, but other varieties do not. Some virus-infected seeds do not have coat mottling symptoms. Sometimes mottling occurs in seed that is not infected with virus. Therefore seed coat mottling is not a good predictor of virus presence in a seed.

Information on these pages is from the cooperative effort of researchers throughout the North Central states. Information from this site can be copied and distributed for educational use. Please credit the source with our name and URL: NCSRP Plant Health Initiative at www.planthealth.info. Please do not use copyrighted photos without permission.