Development of a Damage Function Model for Pratylenchus penetrans on Corn.

Area of Science:

• Agricultural Science
• Nematology
• Crop Protection

Background:

• Pratylenchus penetrans is a significant corn pest in the north-central US, yet its impact on grain yield is understudied.
• Commercial seed treatments target Pratylenchus spp., but robust damage functions are lacking.

Purpose of the Study:

• To develop a damage function for Pratylenchus penetrans using a component error modeling approach.
• To assess the influence of year and site on the relationship between nematode density and corn yield loss.

Main Methods:

• Adapted a component error modeling approach using field data from six site-years.
• Developed 14 regression models comparing nematode population densities (soil and root assays) with proportional yield differences.
• Included pairwise comparisons of nematode densities and associated yield loss.

Main Results:

• Seven of the 14 models were significant, with four based on soil assays and three on root assays.
• The most significant model, based on initial soil assays, estimated yield loss at 0.0142% per nematode.
• Grand mean yield loss across 118 plots was 3.79%, with experimental error being the largest variance component.

Conclusions:

• The developed damage function is more useful for demonstrating P. penetrans impact than for precise field-level yield loss prediction.
• Initial soil assays are as effective, if not superior, to root assays for predicting yield loss.
• The study suggests potential for conservative yield loss estimates due to irrigated loamy sand soil and above-average yields.