I know we aren’t supposed to complain about rain—and I’m not! But I will just say, the unusually wet growing season we have had has led to some challenges. And one of the most significant is the amount of Sudden Death Syndrome we are seeing in the soybean fields this year. SDS is one of the costliest soybean diseases nationwide. Infection occurs early in the spring, and once your field has SDS, there is no getting rid of it. So, you may be wondering, why is she bringing this up now? There’s nothing we can do about it! And while that is true for this growing season, we have the perfect opportunity right now to make some plans for the coming years!
Why is SDS so Noticeable this Year?
Wet, cool conditions favor develop SDS. Not only at planting, (which we had), but also throughout the growing season (which we also had). Moisture allows for growth of the disease which we end up seeing as the toxins translocated throughout the plant. High soil moisture as well as poor drainage will also contribute to more SDS than normal. Fields with SCN are also more prone to SDS infection as they provide feeding/wound sites on the roots for the disease to enter through. Finally, high fertility, high yielding fields may be more prone to severe outbreaks of SDS. In essence, 2019 was the perfect storm.
Take Note of SDS Distribution
Have you noticed driving around lately that you can very easily see the spots in the field where SDS is at? That’s because SDS is causing premature senescence of plants. Healthy plants are remaining green and continuing pod fill, while infected plants are dying. This is the perfect time to do a little crop tour of your fields. Write down which fields you have SDS in. In those fields, is it worse in some spots than others? Is it across the whole field or just in portions? Is it worse than other years? Are there fields that haven’t had SDS symptoms before that have it this year? WRITE ALL THIS DOWN! Any notes you take now will be so useful when planning for upcoming soybeans. If you are doing a typical crop rotation, you may not remember some of the little details like which areas of the field were worst in 2 years time. So, take some time some evening this week and go for a little drive and jot down some notes. Maybe even consider finding some imagery from last week or this week on Encirca or have your fields flown with a drone to record the SDS distribution.
Variety Selection is our #1 Defense
I won’t go into all the details of how the disease functions in the plant. You can find all that info from last years blog post on SDS. However, I am going to talk about some of our best strategies for combating SDS. The best option we have is choosing soybean varieties that are more tolerant to SDS. The best option for SDS resistance in our lineup is with P33A53X which has a rating of 8 for SDS resistance and does exceptionally well in high pressure situations. Other options for above average SDS scores include P37A27X, P42A96X and P40A47X. P37A27X and P42A96X also bring an impressive disease package against frogeye leaf spot and excellent emergence scores. A newer variety, P39A58X, also shows good resistance to SDS in addition to exceptional standability. All of these options are going to go a long way towards resisting the impact that SDS has on the plant and final yield.
Next Line of Defense: Seed Treatment
There is only one mode of action that is known to effectively and consistently curb the impact of SDS, and that is Fluopyram, or the active ingredient in ILeVO. This is a seed applied product that helps protect both the roots and leaves against the toxins produced by SDS. This product has consistently shown between 1.4-2.0 bushel per acre improvement over untreated in a multi-site Pioneer study. The University of Nebraska showed results ranging from 2.8-3.7 bushel per acre advantage.
There are other products on the market that claim to have efficacy against Sudden Death. However, not enough research has been done to prove any claims. Keep your eyes open for new products, but be wary until looking for some research on the products.
By stacking a seed treatment like ILeVO with a resistant variety, we are setting ourselves up for our best possible fight against this yield robber.
We do need to think of the potential risk of spreading this disease during harvest. SDS is soil borne, so on its own can only move centimeters each year. However, it can easily be moved on equipment throughout the field and between fields. This will particularly be a concern if harvest is wet and a significant amount of mud is on tires of equipment. While I know it won’t be the first thing on your mind, if you mud up tires and equipment in a field with high level of SDS, take a few minutes at the field drive to knock off as much mud and soil as you can before heading to the next field to decrease your risk of spreading inoculum. Let’s keep the spread of SDS as localized as possible!
Do you have questions about what SDS looks like? Or how it impacts plants? Check out our blog post entitled Management Steps for Sudden Death Syndrome in Soybeans to learn more about how the disease got to the Midwest, how it works inside of plants, and what management steps we should take to prevent this costly disease.
Do you have questions about the severity or distribution of SDS in your fields? Get in touch with one of the Agronomy Team to learn more about your specific situation and find out what we can do to help!