Corn Stand Reduction and Green Snap (2019-2021)

Stand Reduction: National Crop Insurance Services (NCIS) has conducted research for hail adjusting loss instructions for corn that include assessing losses from stand reduction/loss, defoliation, direct damage to stems and ears, etc.  Past stand reduction research has led to the development of two loss tables for stand reduction/losses. One applies to stand reduction up through the 10th leaf stage (approx. V7) and the other applies to stand reduction losses from the 11th leaf stage (V8) through the 17th leaf stage (V14).  Stand reduction/loss after the 17th leaf stage is currently counted on a 1 for 1 basis (100 plant sample-each plant counts as 1%). This research project will be used to explore yield loss from green snap below the primary ear node as late as tassel stage.  While some secondary ears are produced at lower nodes on snapped plants, the remaining fully-intact plants may to use the extra growing space and compensate with greater per-ear yields.  If this is true, plants in the 18th leaf growth stage through tassel should not be counted on a 1 for 1 loss basis for stand reduction as they currently are.

Green snap:  National Crop Insurance Services defines green snap as a break or severing of the stem between the brace nodes and the primary ear node.  However, it is common for breaks to occur above the primary ear node.  NCIS implemented an exploratory “above the ear node” break in a recently completed research project and results suggested that losses from ‘above the ear breaks’ may be congruent with defoliation losses of a similar magnitude (i.e. 20-25% of leaves lost when break is above ear). This research will further explore the effect of green snap above the primary ear.

Principal Investigator(s):