By Elmore and Abendroth
13 Aug 2006 - Over the past two weeks, storms have caused corn to lean over in northwest, northeast and eastern portions of the state. Corn was between R2 (blister stage) and R4 (dough stage) at the time. Plants that did not have established brace roots were often those that lodged; whereas corn that had a good brace root system received minimal damage. The other important consideration in the amount of lodging that occurred per field is the amount of rootworm feeding present. This feeding causes the total root mass of the plant to be reduced. When a plant's root mass is damaged due to insect feeding or if the plant does not have brace roots set, it will have an increased risk of lodging when soils become saturated. With the soil more pliable due to the rain, the above-ground weight of the plant causes it to lean in the direction of the wind's force.
Plants that are lodged will often reorient themselves so they are upright; this is called "goosenecking." Lodging not only causes cosmetic damage, it also reduces yield due to decreased light interception, plant reorientation, partial loss of root activity, and lower harvesting efficiency.
Research data is limited on the effect of lodging this time of year. We believe that yields could be reduced up to 10% due to lower kernel weights. If lodging occurred in a field during pollination (R1), yield loss would be expected to be greater - possibly up to 20%. Make sure to walk the damaged field(s) to decipher what caused the field to be more susceptible than other fields. This will be useful information in future management decisions.
Please contact Roger Elmore (firstname.lastname@example.org) or Lori Abendroth (email@example.com) with questions you have. You may also refer to an article in the ICM Newsletter which addresses root lodging that occurred last year (http://www.ipm.iastate.edu/ipm/icm/2005/...lodge.html)