Soggy, cold spring weather keeps tractors, planters in the shed
By BROOKS TAYLOR
Mt. Pleasant News
Undoubtedly, there are a number of itchy stewards of the soil out there.
Their frustration is going to grow over the next several days as they look out the window and see rain drops saturating the ground where corn planters are supposed to be ingesting seed into the ground.
Virgil Schmitt, ISU Extension agriculture agronomist for southeast Iowa, wrote in this week’s crop report that with soils being warm and soils in generally good condition, corn planters are starting to roll.
“However, it looks like soil temperatures may flirt with 50 degrees over the weekend, and corn does not grow at temperatures below 50 degrees,” he cautioned. “If the germination process has started, it is difficult for the plants to stop the process and then start up again. Fields with a history of pythium seedling rots are especially vulnerable to the rots if the soils are both wet and cold.”
The optimum soil temperature for corn planting, Schmitt insists, is 55 degrees or above.
Roger Elmore, an Iowa State University corn specialist, said in his column this week in “Iowa Farmer Today” that there is some corn imbedded in fairly warm Iowa soil. But that fairly warm soil is not in southeast Iowa.
“After a long bout of cold, wet weather, soil temperatures warmed up over 50 degrees over the entire state with cooler temperatures in east-central and southeast Iowa,” Elmore said. The warmest temperatures were 60 degrees in Lyon County (extreme northwest Iowa) and other regions in northwest Iowa.
Elmore admitted there are probably some Iowa fields conducive for planting.
Last week’s growing degree day (GDD) accumulations across Iowa lagged well behind the normal 56 degrees he said. South-central and southeast Iowa cropping districts (CD) fell the furthest back, each at 47 percent of normal; the northwest crop district was at 71 percent of normal GDD accumulation for last week.
“Although we’ve experienced some good drying conditions the last few days, it’s not going to last,” Elmore said earlier this week. “Rain is forecast for most of the week…Central Iowa’s forecast for temperatures for the week is to drop into the mid 30s later in the week. If that happens, forecast GDD accumulations will barely reach half the normal 60 GDD for the next seven days in central Iowa. Soil temperatures will nosedive.”
Optimum corn planting dates vary across Iowa, Elmore said, depending on soil moisture and temperature. The optimum dates in southern Iowa are from April 11 to May 13.
“Although corn kernels absorb soil moisture when soil temperatures are less than 50 degrees, they will not begin germination until soil temperatures reach almost 50 degrees or higher,” Elmore explained. “If the five-to-seven-day forecast calls for a good chance of cold, wet weather settling back in for a while keep the seed in the bag…We’ve not yet experienced the best planting date for 2013, and it won’t likely be this week.”
Schmitt, in his crop report, also warned of stalk borers being a concern for corn grown adjacent to grass areas, such as ditches and waterways, or in areas where there was a grass week or ragweed control problem in 2012.
“Along and south of Highway 34 (Mt. Pleasant, Burlington, Ft. Madison and Keokuk areas) we are approaching the time for one management strategy, which is to spray an insecticide to those areas immediately before egg hitch to kill the larvae as they hatch,” the agronomist noted.
Schmitt said the time or egg hatch is controlled by GDD, so the egg hatch will slowly move north as more growing GDDs accumulate there. Stalk borer activity is based on growing degree days base 41. Growing degree days base 41 for Burlington, Davenport, Cedar Rapids and Dubuque, as well as additional stalk borer management information, are posted at www.extension.iastate.edu/Pages/eccrops/stalkborer.html.