A survey of Indiana soybean producers by Purdue University found that growers are planting much earlier than they did a decade ago. Producers said they've moved up their planting operations in order to increase the odds of harvesting bigger crops and avoid planting delays caused by late spring rain, says Shawn Conley, Purdue Extension soybean specialist and survey coordinator.

More than 1,300 farmers across the state participated in the Purdue survey, conducted this past fall. Complete survey results will be released in a report due out this spring.

"In recent years we've seen a movement among growers to plant earlier," Conley says. "In our survey we found that 67 percent of growers across the state of Indiana are planting their soybeans earlier today than they did 10 years ago. They are planting anywhere from one to three weeks earlier."

The early planting trend also falls along regional lines, Conley says. "The interesting thing is that it’s not the growers in the southern part of Indiana planting earlier. They are planting at about the same time they've planted in the past, because they have a little bit longer planting window," he says. "Instead, it’s those growers in the central and northern parts of the state that are pushing that date earlier and earlier every year."

Thirty-three percent of the Indiana soybean acres in 2005 were planted by May 8, slightly ahead of the 32 percent average for the same period between 2000 and 2004, according to the Indiana Agricultural Statistics Service. By comparison, the 1991-95 planting average for the period ending May 12 was 18 percent.

"When we asked growers the main reasons for planting earlier, the No. 1 reason they gave was yield," Conley says. "Growers strongly believe that they’re getting significantly higher yields by planting their soybeans earlier. The No. 2 reason for earlier planting is weather.

"Growers feel if they don't get their beans planted by the end of April or first part of May and we get into a rainy stretch, planting will be pushed back to the end of May or the first part of June. When that happens they get out of the optimum window for planting soybeans."

As a rule of thumb, the ideal planting period for soybeans is between April 20 and May 26, Conley says. Producers who plant soybeans earlier than April 26 run the risk of frost damage. Those who plant later than May 26 aren't likely to achieve the highest possible yields.

Frost damage is not the only possible threat from planting early. Crops also are susceptible to disease and insect infestations, Conley says.

"Early planting not only increases risk of poor stand establishment because of seedling blight, it also increases risk of Sudden Death Syndrome, or SDS," he says. "There's a relationship between early planting and an increased incidence of SDS."

Although foliar symptoms of SDS don't appear until after pods have begun to set, infection occurs much earlier, Conley says. Wet fields and plant stress early in the crop season set the stage for the disease.

"While planting at the optimum time does not eliminate the risk of SDS, risk seems to be greater with earlier planting," Conley says. "We would encourage growers who plant their beans early to make sure the varieties they're planting earlier have some tolerance to SDS.

"Another pitfall with earlier planting is insects such as bean leaf beetle, which can transmit viruses. We're not talking about a lot of acres but, typically, it’s the early planted beans where the bean leaf beetle shows up first."

Bean leaf beetles can carry the bean pod mottle virus, among others. The virus damages soybean leaves and limits the plant's ability to produce seeds.

Additional information about soybean production is available on Conley's Cool Bean Web site, located at www.coolbean.info .