By Roger Elmore and Lori Abendroth
18 Jul 2007 -
Corn is tasseling and silking across Iowa. A sizeable portion of the state is suffering through dry conditions while others have had measureable precipitation in the last few days. Unfortunately, the rain came with hail and strong winds earlier this week which resulted in corn root lodging in parts of Iowa.
An article on our web site discusses research findings that show the impact lodging this time of year has on yield.
A portion of that article along with some information relative to the events of this past week is below:
There is little research documenting the effect root lodging has on yield this time of year. Simulated root-lodging research at the University of Wisconsin addressed the yield impact of lodging at three different growth stages in 1985 and 1986.
Lodging did not affect silking, but it did increase the number of barren plants. Ears per plant were also reduced. We speculate that kernels per ear and seed weight were likely affected too. Lodging like this not only affects yield components but also disrupts the entire plant orientation. Reorienting the canopy to better intercept light comes at a high energy cost to the plant.
The Wisconsin research found yield losses to be from 14 to 25 percent when lodging occurred on or after V17 (17th leaf stage). Overall, yields were reduced 3-4% when corn was lodged from V10/V12, 8-10% when corn was lodged from V13/V15. Yield loss would be lessened if lodging occurred after R1, because VT/R1 are the most critical stages for leaf loss, plant loss, etc. to occur.
Many wonder if pollination will be affected. The Wisconsin research above was conducted over 20 years ago. Synchronization of pollen dispersal and silk appearance, often referred to as ‘nick,’ is closer with modern hybrids than it was in the 1980’s. In some situations, we may see a delay in silk appearance on lodged plants relative to pollen dispersal since silking is often more susceptible to stress than pollen dispersal. Poorer pollen-silk synchronization may result in the failure for some ears to silk before pollen dispersal is finished. This may result in more barren plants than what is shown in the Wisconsin research.
What can we learn that will reduce root lodging in the future?
-Identify whether the lodging was primarily caused by rootworm larvae feeding, poor root development (due primarily to cold, wet soil conditions), or due to other circumstances. Understanding the cause will provide valuable information and direction when making changes to how the field is managed.
-In areas where rootworm larvae feeding was the cause of the root lodging, use soil insecticides, crop rotations, or Bt hybrids resistant to rootworm feeding.
-Hybrids vary in their susceptibility to lodging, select hybrids that withstand root lodging.