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Beyond the Rows is a Monsanto Company blog focused on one of the world’s most important industries, agriculture. Monsanto employees write about Monsanto’s business, the agriculture industry, and the farmer.
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Sudden Death Syndrome Making its Mark in Soybeans

A healthy soybean field on the left, a field with medium to heavy Sudden Death Syndrome pressure on the right.

I couldn’t cut it as a farmer—for a multitude of reasons—but primarily, I couldn’t stomach the business risks involved. There are risks such as weather and disease that are completely out of your hands no matter how much forethought and planning you do.

It appears that U.S. soybean farmers are facing one such risk this year with Sudden Death Syndrome (SDS), based on news reports and feedback from farmers and Monsanto sales teams. Farmers are scouting, or surveying, their fields for signs of SDS. Symptoms generally show up in July/August, but can often be mistaken for other diseases such as brown stem rot (BSR). The Upper Midwest—Minnesota, Iowa, Illinois, Wisconsin, Nebraska, Missouri, South Dakota—seem to be especially affected. The USDA warned Monday that the amount of acreage impacted is becoming a concern.

To learn more, I called up Steve Arndorfer, a Monsanto sales rep in north central Iowa, which has been hard hit by the disease.

“Most fields are spotty with it, and those south of us are worse,” says Steve.

Sudden Death, I learned, is as ominous as it sounds. The disease is caused by a fungus (Fusarium virguliforme) naturally present in the soil. The fungus thrives in wet damp soil and cool temperatures just like we had this spring. Soil compaction is also a factor. Field entrances or other areas where grain carts drove in a previous year and compressed the soil exhibit more severe symptoms.

With the right weather and soil conditions spurring it into action, the fungus makes its way into the roots and base of the soybean stem. Then the fungus spreads up through the plant’s leaves, showcasing its presence in small yellow spots. The spots grow larger and larger, eventually developing a brown center. The leaves wither and die.

All of this occurs as the soybean is growing and developing flowers and bean pods. Then suddenly, the plant dies. Flowers fall off, and pods stop filling. The result is either reduced seed size or no seeds at all equating to lost yield. Yield loss can be anywhere from “slight” to 100%.

“They die right on the spot,” says Steve. “They [farmers] end up with 0-10 bushel beans in the affected areas. It’s like the crop just froze and stop.”

The worst part about SDS?

“There’s absolutely nothing there you can do about it,” he says. Fungicides are ineffective. Once SDS hits a field, you simply sit back, watch and hope that the disease doesn’t take out your whole crop.

Steve says his farmers are already asking about seed selection for next year. Monsanto offers SDS-tolerant varieties in its product lineup. Monsanto breeders look for soybean products within its program that are naturally more resistant to SDS. We screen and rate the plants to test their natural reaction against SDS. Then, we choose those varieties with higher levels of resistance and breed with them to improve the SDS tolerance of all of our soybean seed varieties. It’s important to note that no soybean variety is completely resistant to the disease, and all soybeans are susceptible if the right weather/soil conditions are present.

Even so, farmers should not choose seed for next year based solely on SDS-tolerance. That’s because SDS is not a yearly occurrence, and farmers will most likely rotate crops next year.

“SDS has been around since the ’70s, but we don’t see it very often so you can’t put rhyme or reason on it,” says Steve. “I guarantee next year won’t be like this year.”

Farmers should also look for soybean cyst nematode (SCN) tolerance in their seed varieties since researchers have identified interactions between the two diseases.

Monsanto’s technical personnel issued have issued an agronomic alert with tips for SDS management, you can find it below.

Agronomic ALERT – Sudden Death Syndrome in Soybean – Northern US (2)

Or, see some related resources:

Scouting and identifying SDS and brown stem rot (University of Wisconsin video)
How Soybean Sudden Death Syndrome Looks at the Root (Ohio State Extension)

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