Jon J. Tollefson

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Corn rootworm larval feeding on corn roots can significantly reduce grain yield by interfering with photosynthetic rates, limiting the uptake of water and nutrients, and by increasing the plant's susceptibility to lodging. Of the techniques developed to measure the efficacy of corn rootworm larval control tactics, root damage ratings have generally been(More)
This Australian study, a replication of Canadian research by Dibert & Goldenberg, was undertaken to explore the relationship between preceptors' perceptions of benefits, rewards and support, and their commitment to the preceptor role. A convenience sample of 134 nurse preceptors involved in an undergraduate nursing course were invited to complete a(More)
The theory and a case study are presented for a class of techniques known as stochastic simulation. Stochastic simulations can characterize the certainty of estimates of spatially and/or temporally correlated ecological variables. Rather than merely providing a unique estimate, a conditional probability distribution is built for the unsampled location. This(More)
In 2001, a self-administered questionnaire was sent to 1000 corn, Zea mays L., farmers in each of five states (Illinois, Indiana, Iowa, Minnesota, and Nebraska) to evaluate their perceptions of transgenic corn designed to control the European corn borer, Ostrinia nubilalis (Hübner), and corn rootworms, Diabrotica spp. Respondents returned 1,313 surveys(More)
The most common management options for corn rootworms are rotating corn with nonhost crops, planting genetically engineered corn resistant to corn rootworms (e.g., Bacillus thuringiensis [Bt] corn), and treating with a soil insecticide at planting time. Because these control tactics are preventive, the decision to apply controls has been made without any(More)
iv Chapter 1. General introduction 1 Organization of Dissertation 9 References 11 Chapter 2. Mobility of tylosin and enteric bacteria in soil columns 17 Introduction 17 Materials and Methods 21 Results and Discussion 24 Acknowledgements 31 References 31 Figures 37 Chapter 3. Dissipation of tylosin in surface water 40 Abstract 40 Introduction 41 Methods 42(More)
This paper outlines some important issues discovered about undertaking qualitative interviews. A description of a study that involved interviewing the authors' students is followed by discussion of aspects of the interviewing process that became apparent during analysis of those interviews. Problems that were encountered with retrospective interviews, power(More)
This paper outlines a research project aimed at changing the levels of reflection of preregistration nursing students in a tertiary institution. Whilst reflection is widely espoused now in nursing, few studies have been found that identify whether the level of reflective writing can be identified or developed by students. Anecdotal and research evidence(More)
This paper reframes an interpretive study as critical inquiry as the researchers interrogate their roles and authority in the 'reading' of what is valued as reflective. Working from data collected in written philosophies and interviews within the context of a one-year subject aimed at developing reflective practice and an appreciation of ways of knowing,(More)
The dispersion of root injury to Zea mays L. by corn rootworm, Diabrotica spp., larvae was characterized using geostatistics to determine the appropriate sampling distance to obtain independent estimates of root injury. We also investigated the effect of the root injury levels on the spatial dependence of root injury at three different spatial scales:(More)