Purdue University researchers have discovered that a winter weed common throughout Indiana will facilitate reproduction and population increases of soybean cyst nematode even when soybeans are not present in the field.

Purple deadnettle is a winter annual weed that usually emerges after harvest, overwinters as a seedling and fully develops in the spring. Purdue researchers discovered this fall that soybean cyst nematodes (SCN) use the purple deadnettle as an alternative host for feeding and reproducing when soybeans haven't been planted.

"SCN is the No. 1 pest problem with soybeans," said Jamal Faghihi, research nematologist. "We are trying to understand the relationship between purple deadnettle and soybeans."

Additional research is being done to determine if juvenile soybean cyst nematodes can last through the winter in the weeds' roots.

"SCN infests purple deadnettle roots, just like they do on a susceptible soybean variety," said Bill Johnson, an associate professor of weed science.

Soybean cyst nematode has been detected in 82 of the state's 92 counties. Johnson said that 2-4 million acres in Indiana have been affected. To protect soybean plants from this pest, researchers are trying to find the best timing to control purple deadnettle to reduce soybean cyst nematode densities.

For now, Purdue experts offer some tactics to reduce the nematodes.

One is rotating crops to slow growth by taking away the pest's food source. Research has shown that the nematodes still live in the soil, but rotating crops will aid in decreasing the population. Another strategy is to use a soybean cyst nematode resistant soybean variety to protect the plant from the pest. In addition, Purdue researchers have shown that some winter weed management tactics can cause slight reductions in nematode populations. Research supported by the Indiana Soybean Board will evaluate the impact of winter management tactics on the weed and soybean cyst nematode populations in Indiana.