Soybean cyst nematodes survive extremely cold winter

Despite harsh winter conditions, the SCN survival rate is almost 100%.

The record low temperatures over the past few months may reduce some pest populations this spring, but university and industry experts predict soybean cyst nematodes (SCN) will still threaten yields.

While many may believe that the extreme cold temperatures this winter killed SCN over winter, this is not actually the case. In fact, there is almost 100% survival of SCN over the winters in the Midwest - no matter how cold.

“Many growers hope the cold weather we’ve been experiencing will help decrease pest populations,” said Dale Ireland, Ph.D., seed treatment technical product lead at Syngenta. “But it doesn’t affect SCN.”

According to the Iowa State University Extension, unusually large numbers of SCN may infest fields where soybeans were grown in 2012—a year when SCN reproduction was particularly high. The number of SCN eggs in the soil at the time of planting contributes significantly to the degree of damage and yield loss to SCN. With an overwintering survival rate of nearly 100%, the potential for damage in 2014 is great.

The most devastating pest to soybeans in the U.S., SCN cost producers over $1 billion last year.

Extremely high SCN reproduction was observed in Iowa in 2012 on both susceptible soybean varieties and SCN-resistant soybeans with the PI 88788 source of resistance. The very large increases in SCN numbers in 2012 are believed to be somehow related to the extremely dry soil conditions that occurred that year.

The University of Nebraska – Lincoln explained that losses caused by SCN can be reduced once a farmer knows SCN is present in the field, but can still reduce yield by 20% to 30%, even when plants appear to be green, healthy and have no visible symptoms. Often the first indication of an SCN problem is soybean yields that hit a plateau, or even start to drop off, while corn yields continue to increase in that field. Soil testing is the best way to determine if SCN is present.

To help manage and reduce SCN populations in SCN-infested fields, researchers at the Iowa State University Extension suggest rotating crops, selecting SCN-resistant varieties and using appropriate seed treatments.

“Choosing a variety with high-yield potential and good nematode tolerance along with a nematicide seed treatment is vital to managing SCN,” Ireland said.

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