A Negative Binomial Regression Model of the Observed Population Density of Heterodera glycines after Annual Corn Rotation in Nebraska

Oscar Pérez-Hernández, Loren J. Giesler, Joseph M. Hilbe

Research output: Contribution to journalArticle

Abstract

In Nebraska, rotation of soybean (Glycine max) fields to corn (Zea mays) is a major practice to manage the soybean cyst nematode (SCN; Heterodera glycines). However, factors associated with SCN population density decline during corn rotation are not clearly defined. This study addresses that question using a modeling approach. Seventy-nine fields were sampled in 2009, 2010, and 2011 to determine SCN population densities (eggs/100 cm3 of soil) before and after rotation. After rigorous field screening and model testing and validation, the regression model Log dðPf Þ = − 2:3360 + 0:8368LogPi + 0:4333pH was developed, where Log Pf is the natural log of SCN eggs at the end of the rotation year, Pi is the population density before rotation, and pH is the soil pH. Model goodness-of-fit was assessed through residual analysis, information criteria, and other remedial measures. Model overdispersion was 1.04. Validation in a 50 and a 75% random sample from the original data set showed little change in model regression coefficients, standard errors, and associated significance, confirming model fit and performance. The model indicates that for one-unit increase in soil pH, SCN Pf is expected to increase by 53.7% at constant Pi, and correspondingly, a 10% change in Pi will result in about 8.3% change in Pf at constant soil pH. The model suggested that SCN population levels before corn rotation and soil pH are major determinants of observed SCN population density reduction after annual corn rotation in Nebraska. This model has potential for use in SCN risk analysis and in predicting SCN population decline after corn rotation in the state.

Original languageEnglish (US)
Pages (from-to)3093-3100
Number of pages8
JournalPlant disease
Volume103
Issue number12
DOIs
StatePublished - Jan 1 2019

Keywords

  • Corn rotation
  • Cyst nematode epidemiology
  • Disease development
  • Disease management
  • Epidemiology
  • Negative binomial
  • Nematode management
  • Oilseeds and legumes
  • Spread

ASJC Scopus subject areas

  • Agronomy and Crop Science
  • Plant Science

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