Corn stalk lodging: A forensic engineering approach provides insights into failure patterns and mechanisms

Stalk lodging is essentially a structural failure. It was therefore hypothesized that application of structural and forensic engineering principles would provide novel insights into the problem of late-season stalk lodging of maize (Zea mays L.). This study presents results from a structural engineering failure analysis of corn stalk lodging, involving detailed inspection and measurements of lodged stalks and a multidimensional imaging study to assess stalk architecture based on structural engineering principles. This work involved infield observation of >20 varieties of lodged corn stalk in eight international locations and detailed geometric analysis of four varieties. Analysis of collected data revealed very strong, yet previously unreported, patterns in corn stalk lodging. Corn stalks predominantly fail (break) by creasing, fall in the direction of the minor diameter of the cross section, and break within 4 cm of a node. These failure patterns, across a broad sampling of varieties and environments, suggest a consistent weakness in maize stalk architecture, indicating that a common solution might be identified to strengthen maize stalks. Structural engineering analysis of stalk architecture and morphology revealed that several geometric stress concentrators (features known from engineering theory to increase local stresses) occur in the predominant failure region of corn stalk. Identified stress concentrators include surface irregularities, sharp changes in diameter, and voids occurring in the stalk pith. Each of these stalk features persist across different international locations, environmental conditions, and hybrid varieties. These findings support the use of new selective breeding approaches that focus on stalk morphology and structural engineering analysis of corn stalk architecture to develop lodging resistant varieties of maize.