Optimizing Helicoverpa zea (Lepidoptera: Noctuidae) insecticidal efficacy in Minnesota sweet corn: A logistic regression to assess timing parameters

Eric C. Burkness, Tederson L. Galvan, W. D. Hutchison

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

Late-season plantings of sweet corn in Minnesota result in an abundant supply of silking corn, Zea mays L., throughout August to early September that is highly attractive to the corn earworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae). During a 10-yr period, 1997-2006, insecticide efficacy trials were conducted in late-planted sweet corn in Minnesota for management of H. zea. These data were used to develop a logistic regression model to identify the variables and interactions that most influenced efficacy (proportion control) of late-instar H. zea. The pyrethroid lambda-cyhalothrin (0.028 kg [AI] /ha) is a commonly used insecticide in sweet corn and was therefore chosen for use in parameter evaluation. Three variables were found to be significant (α = 0.05), the percentage of plants silking at the time of the first insecticide application, the interval between the first and second insecticide applications, and the interval between the last insecticide application and harvest. Odds ratio estimates indicated that as the percentage of plants silking at the time of first application increased, control of H. zea increased. As the interval between the first and second insecticide application increased, control of H. zea decreased. Finally, as the interval between the last insecticide application and harvest increased, control of H. zea increased. An additional timing trial was conducted in 2007 by using lambda-cyhalothrin, to evaluate the impact of the percentage of plants silking at the first application. The results indicated no significant differences in efficacy against late-instar H. zea at 0, 50, 90, and 100% of plants silking at the first application (regimes of five or more sprays). The implications of these effects are discussed within the context of current integrated pest management programs for late-planted sweet corn in the upper midwestern United States.

Original languageEnglish (US)
Pages (from-to)677-684
Number of pages8
JournalJournal of economic entomology
Volume102
Issue number2
DOIs
StatePublished - Apr 1 2009

Keywords

  • IPM
  • Insecticidal control
  • Odds ratio

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