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Seeing SDS in Your Treated Soybeans?

September 20, 2021
typical sudden death syndrome symptoms

Typical Sudden Death Syndrome leaf symptoms.

Sudden Death Syndrome (SDS) has been appearing in fields in recent weeks, even those that were planted with SDS-resistant varieties and/or with an SDS seed treatment. SDS is present in fields all season long but exhibits 2 separate phases of infection in a soybean plant. The first is a root rot phase where the fungus exists within the plant’s roots. The second, and more obvious phase of infection, is a foliar phase in the canopy.

Did you treat your soybeans with an SDS seed treatment this season and still see signs of SDS in your field? Here’s why:

  • Environmental conditions heavily influence whether SDS exhibits foliar symptoms, with cooler, wetter conditions early in the growing season favoring SDS infection.
    • Under cooler, wetter conditions, SDS will continue to infect and grow within the root system without above-ground symptoms, often until early to mid-August.
    • In the foliar phase, toxins from the root infection are transported up from the root system into the leaf canopy.
    • These toxins cause small yellow/chlorotic flecks or spots that enlarge, eventually destroying large amounts of the leaf canopy.
  • Saltro® fungicide seed treatment works by limiting the early-season root infection phase of SDS and by protecting developing roots from Soybean Cyst Nematode (SCN) feeding.
    • This early-season protection also allows the plant to establish a robust root system and quick development above-ground.
    • However, there is no chemical or genetic solution for SDS that will entirely prevent the disease from showing up under the right environmental conditions.
  • No seed, soil-applied or over-the-crop solution provides 100% control of weeds, nematodes, disease or insect pests.
    • When used according to label directions, Saltro fungicide seed treatment provides protection from SDS, but not immunity.
    • Saltro and other SDS treatments are NOT an eradicant; you will still see some SDS in the canopy, but predictably less and later than if you did not use it.
    • Any yield loss from SDS should not be as severe as it may have been without Saltro.
  • When evaluating chemical controls, a side-by-side comparison in the same field on the same soybean variety is the best way of determining differences in product efficacy.
    • A check strip of soybeans with no SDS treatment in a field is the only way to confirm how much worse a particular field that’s been treated by an SDS seed treatment could have fared without the treatment.

Fusarium virguliforme on soybean root.

Unique blue-colored structures of Fusarium virguliforme, the causal organism of SDS, on a mature soybean root.

Additional management tools for SDS include avoiding early planting, tiling poorly drained soils, and planting SDS- and SCN-resistant varieties. But be aware there are no resistant lines that avoid SDS entirely. Soybean variety SDS scores vary widely among genetics, and care should be taken to ensure that the best SDS-score varieties are selected for fields where there is a history of SDS. Overlapping genetic resistance, SDS-mitigating cultural practices and chemical control through seed treatments like Saltro will lead to the best possible outcome in the fight against SDS.

Saltro is the latest SDHI fungicide offered by Syngenta Seedcare. It contains Adepidyn® technology, which provides the most intrinsic activity against Fusarium virguliforme, the causal organism of SDS, of any seed treatment available in the U.S.

SDS-infected plants protected by Saltro compared to an untreated row

On the left are SDS-infected plants protected by Saltro compared to an untreated row, where SDS symptoms are developing.

Although you may still see signs of SDS in your Saltro-treated fields this season, the effects of the disease will be less than if you hadn’t used the treatment due to the higher intrinsic protection it provides and the elimination of early-season plant stress.

 Visit WhySaltro.com to learn more.

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All photos are either the property of Syngenta or are used with permission.

Syngenta hereby disclaims any liability for third party websites referenced herein.

Product performance assumes disease presence.

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