| Disease: Viruses |
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Soybean Viruses - Management
Virus management includes a combination of strategies depending on the virus or viruses involved, and may include:
- soybean variety selection
- planting virus-free seed
- control of insect vectors
- crop management plans to avoid periods of peak insect activity
Accurate diagnosis is important
Symptoms of virus diseases look similar. But because of the specific plant-insect-virus relationships involved, effective management requires accurate knowledge of which virus (or viruses) are causing the most prevalent virus problem. Most diagnostic clinics in the North Central region can perform serological diagnostic tests if a virus infection is suspected. Send in green, symptomatic leaves.
Spray for insect vectors?
A cooperative study in IA and WI found that the introduction of the soybean aphid is not expected to make virus problems worse; however, the study showed that disease management cannot be obtained through attempts to control the aphids that transmit the virus. The solution? Disease resistance. Read more in the ICM newsletter»
Seed testing for viruses
Planting virus-free seeds is an important control strategy. Infected seeds are the most important means by which Soybean Mosaic virus and Tobacco Streak virus are introduced into a soybean field. Bean Pod Mottle virus can also be introduced in seed.
When testing seed for the presence of viruses, it is important that the test distinguish between virus in the seed coat (called seedborne) and virus in the seed embryo (called seed transmitted). ONLY virus in the seed embryo will be transmitted to the seedling when planted.
Commonly, seed-testing laboratories prepare a seed extract for virus testing by grinding a seed sample; hence, seedborne (in the seed coat) virus is detected. The test does not distinguish between seedborne and seed-transmitted virus. Therefore, it can't tell you whether the seed is safe to plant or not - many of the positive readings will be for seed that actually poses no risk of virus transmission. Seed-transmitted virus can only be detected by using grow-out tests where soybean seedlings are tested for virus.
Adapted from Virus-induced soybean seed problems , John Hill, Iowa State University Integrated Crop Management Newsletter