Managing SDS
Due to the number of SDS mentions in this week’s report, we wanted to share some SDS management tips shared in one of Monsanto’s recent Agronomic Alerts.
If SDS is present, little can be done this season. However, management decisions for next year can be made. Fungicides are not an option for SDS control due to the nature and timing of the disease. An integrated management plan for SDS may include the following:
- Balance the overall disease package. Balancing the disease package in next year’s crop is better than focusing on SDS tolerance, especially since soybean fields from this year will likely not be soybean fields next year.
- Plant soybeans described as resistant or moderately resistant to soybean cyst nematode (SCN).
- Delay planting or plant earlier maturing varieties to possibly help soybeans escape infection from SDS.
- Implement cultural practices that improve drainage in low spots, reduce SCN populations, or remove soil compaction layers may lessen SDS severity.
We also want to share SDS management tips provided in last week’s blog (you’ll need to scroll to the bottom of the article), as well as a helpful Iowa State Extension article that was published recently by Alison Robertson and Daren Mueller, Department of Plant Pathology.
White Mold
There were a few mentions of white mold in this week’s crop report, and a recent Iowa State Extension article states that fields at higher risk of developing white mold are those that had disease in previous years and are in high-yielding sites where the canopy closed early. Also, fields that have had plenty of soil moisture, high humidity and little airflow. Below is a link to an article from Iowa State Extension highlighting white mold management tips – while it may be too late to apply some tips for this year’s crop, there are some general management tips you may want to keep in mind if you’re seeing white mold in your field this year.
http://www.extension.iastate.edu/CropNews/2010/1230yang.htm
Central Iowa
Bob Collins’ area recorded another 5 inches of rain on Monday night with more rain and flooding last night. Outside of flooding, the crops look pretty good although SDS is showing up in some bean fields.
A large storm passed through Bart Peterson’s western area over the weekend. The storm had strong winds and rain, leaving some corn fields flat near the Schaller area. Beans are in the R3 to R5 stages and in a plot in North Central Iowa, the 100- to 102-day corn is already denting.
Below are some images that show the incredible rainfall Ames, Iowa, has already received. (Note: More rain has fallen already this month than normally falls in the entire month.) The second photo is Ames’ Hilton Coliseum on August 11.
East Central Iowa
Sudden Death Syndrome is hitting Brad Beatty’s eastern Iowa territory hard, so below he addresses the top questions he’s getting asked:
- What is Sudden Death Syndrome? Sudden Death Syndrome (SDS) of soybeans is caused by a fungus strain known as Fusarium solani. The name “sudden death” is misleading since the disease may take weeks to fully develop. However, symptoms may not be noticeable until the disease is well advanced and the leaves turn or start to defoliate.
- What can I do to prevent SDS? First, identify the disease. Second, in fields where SDS was present a year or two ago (when the field was last in soybeans), make sure that you plant a soybean that has high tolerance to SDS. Third, SDS likes to hit soybeans that were planted early and /or fuller season varieties because early planting conditions are more favorable for infection. Thus, planting beans later when the soils are warmer and dryer will help. Fourth, where feasible, improve soil drainage in the field and reduce soil compaction to help the field drain excess water. Fifth, varying maturity through a group or varying planting dates can also be an effective way of spreading out growth stages. Sixth, control cyst populations. Research shows that presents of soybean cyst nematode can help spread SDS because of the added stress that they put on the soybean plant. Soybean cysts have been found to carry this fungus, but it hasn’t been proven that they can translocate this fungus into the soybean plant. Although crop rotation has had little effect on this disease, farmers should not plant continuous soybeans. There is no spray that can help SDS.
- What will my yield loss be? Losses commonly do not exceed 10% to 15%, but it can be as high as 50% in severe situations.
- What are the symptoms? SDS symptoms begin as small yellow spots on the upper most leaves of a plant. These may get overlooked or may be easily misdiagnosed. Spots gradually enlarge and develop a brown dead center. They continue to enlarge until all of the interveinal tissues are killed, leaving a green vein pattern on the leaf. The time involved for this symptom to develop is dependent on weather conditions and variety in the field.
North Central Iowa
Kevin Meyer reports another great week for crop development in his region. Corn is well into the grain fill and looks good overall. He’s keeping a cautious eye on late season diseases and related stalk quality issues. Soybeans are being affected by SDS and White Mold will likely show up in the near future. Producers need to take note of these fields and make variety selections that will offer some resistance as they rotate soybeans back into these fields. This week brought light increases in aphid populations but numbers are still below threshold for treatment.
What a difference a week makes! Last week we didn’t see much disease or insect pressure but this week we’re seeing a lot of Sudden Death Syndrome (SDS) in soybeans. This soil-borne disease, which originated in the south and has worked its way north, made its presence known over the last seven days in North Central Iowa. Soybean aphids are also starting to reach threshold numbers in some areas, keep we’re keeping a sharp eye out for them as well. If the temperature breaks, the population of aphids could rise.
South Central Iowa
The northwestern part of Travis Slusher’s area has seen heavy torrential rains over the last few days, creating flash flooding issues. On Monday, he witnessed fields in this area where corn had water standing over the ears with only the top couple of feet visible of the plant. This will surely cause stalk and grain quality issues in these areas come harvest. The northern part of this territory is showing heavy SDS in soybeans. As you move further south, SDS becomes less prevalent but it is still showing up in small areas throughout this region. Most of the corn in South Central Iowa is beginning to dent with the soybeans beginning to fill the pods.
Northeast Iowa
The big news in Nick Benson’s territory is how well soybeans are doing. His area has received plenty of moisture for pod fill, and barring a large onset of White Mold and SDS, we should be looking at some nice bean yields. Aphid numbers are now starting to reach thresholds in some fields, but in general, he doesn’t think many fields will be sprayed this year in his area. Corn is looking exceptional in fields that have good drainage and an ample amount of Nitrogen. Where that isn’t the case, premature senescence is occurring. Nick has looked at some good fields of Latham® Hi‑Tech Hybrids 5425 VT3 where ears are already busting out of the husk. In a field of LH 5777 SS, he saw perfect worm-free ears, which should add to the overall yield. The next big move in this area is the silage harvest; farmers are only a few weeks out on that as this corn is maturing at a very rapid pace.
Wisconsin
Steve Bailie reports the crops are looking good in his area. In the southwestern part of the state, many soybeans are at R4-R5 stage. Many of Latham Hi‑Tech Soybeans with the Genuity® Roundup Ready® 2 Yield trait have a number of 4 bean pods again this year. Insect pressure has backed off, and many growers are hoping to get away without spraying. Fungicide applications on beans are coming to an end. White Mold is starting to show up in bottom ground. Unfortunately, the southwest received rains Sunday afternoon and early Monday morning that caused many of the beans fields to lodge.
South Dakota
The sun is finally shinning in South Dakota! The crops are fairing well despite the recent weather patterns. Farmers are still scouting for aphids but have seen very few. The next problem will be battling the wet fields when it is time to cut silage. In South Dakota, corn has passed through the R2 stage and soybeans are in R4.
Central Nebraska
Steve Edwards says his area is still headed for a bumper corn crop. The recent high heat followed completion of pollination, so it should have little or no effect on yield. Good soil moisture, GDUs and the crop response to superior growing conditions have been excellent. There was some slight hail damage in western north central Nebraska, but it wasn’t significant and most of the damaged fields will have average yields. Soybeans are headed for a slightly above average yield. It remains to be seen if the string of days with extremely high heat will shed blooms and depress yield, but he doubts it because he hasn’t seen signs of stress on the crop. The only down side to this year has been the excessive moisture for the soybeans in east central Nebraska, the effects of which will haunt low lying or poorly drained soils throughout the year. All things considered, it will still be at least an average yield, if not slightly up from last year.
Minnesota
Jason Obermeyer reports corn is looking great but soybeans are showing some signs of Brown Stem Rot (BSR) and Sudden Death Syndrome (SDS). Plot days are being inked in for the last days of August and September, so we hope to see good crowds in the coming weeks.