Over the last several days we have been monitoring soil temperatures in a field near the Seed Consultants, Inc. main office. At 9:30am on Wednesday April, 11 soil temp at a 2-inch depth was 38 degrees Fahrenheit. After warm, sunny weather, 24 hours later soil temp in the same area of the field was 51 degrees. Corn requires 55 degrees Fahrenheit for germination, soybeans require 50 degrees. Although soil temperatures can reach sufficient levels after a few days of warm weather, it is important to keep in mind that they can drop just as quickly. On Friday April 13 the soil temperatures had climbed to 69 degrees F. However, after cooler weather and 1.3 inches of rain over the weekend, soil temp was at 40 degrees F this morning.
When planting into adequate conditions, it is important to keep the forecast in mind. The first 24 hours a seed is in the ground are critical to its survival, and a cold wet rain in this time period can cause cold shock, which can kill seedlings.
Wet weather is delaying burndown and allowing weeds to continue to develop. Over the last week our agronomy staff has observed marestail (that emerged last fall) beginning to bolt as well as giant ragweed that are 1 to 2 inches tall. Herbicide applications should be made as soon as weather and soil conditions allow. Be sure to follow labeled rates of products and make applications when weeds are no taller than 4 to 6 inches.
As we have observed in the past, spring winds and storms bring with them black cutworm and armyworm moths. Over the last several days the eastern Corn Belt has experienced weather conducive to moth migration north while growing weeds in fields provide areas for moths to lay eggs. Growers should monitor moth reports (click here for Purdue’s Moth Trap Report) and scout fields to determine if pests are present and if an insecticide treatment should be made.