Epidemiology and disease management of Stewart's disease of corn in Iowa

Thumbnail Image
Date
2005-01-01
Authors
Esker, Paul
Major Professor
Advisor
Philip M. Dixon
Forrest W. Nutter, Jr.
Committee Member
Journal Title
Journal ISSN
Volume Title
Publisher
Altmetrics
Authors
Research Projects
Organizational Units
Organizational Unit
Plant Pathology and Microbiology
The Department of Plant Pathology and Microbiology and the Department of Entomology officially merged as of September 1, 2022. The new department is known as the Department of Plant Pathology, Entomology, and Microbiology (PPEM). The overall mission of the Department is to benefit society through research, teaching, and extension activities that improve pest management and prevent disease. Collectively, the Department consists of about 100 faculty, staff, and students who are engaged in research, teaching, and extension activities that are central to the mission of the College of Agriculture and Life Sciences. The Department possesses state-of-the-art research and teaching facilities in the Advanced Research and Teaching Building and in Science II. In addition, research and extension activities are performed off-campus at the Field Extension Education Laboratory, the Horticulture Station, the Agriculture Engineering/Agronomy Farm, and several Research and Demonstration Farms located around the state. Furthermore, the Department houses the Plant and Insect Diagnostic Clinic, the Iowa Soybean Research Center, the Insect Zoo, and BugGuide. Several USDA-ARS scientists are also affiliated with the Department.
Journal Issue
Is Version Of
Versions
Series
Department
Plant Pathology and Microbiology
Abstract

Research was conducted from 2001 to 2003 in Iowa to determine ideal sampling methods, as well as the effect of planting date with/without seed insecticides to reduce corn flea beetle vector (CFB) (Chaetocnema pulicaria) feeding and Stewart's disease (Pantoea stewartii) of corn. Sampling for CFB's was conducted at Ames, Crawfordsville, and Sutherland in 2001 and Crawfordsville and Johnston in 2002. Yellow sticky cards were placed at 15 combinations (five replications) of height (0.15, 0.3, 0.45, 0.6, 0.9 m) and orientation (vertically, horizontally, or 30° angles) at each location. The 0.3 m and vertically facing cards significantly captured more CFB's (1.1 to 35 times) during 2003. To study the effects of planting date with/without seed insecticides, trials were conducted at Crawfordsville (2002 and 2003). Ten (2002) and eight (2003) planting dates were established in multifactorial combinations with seed insecticide (nontreated, PonchoRTM, CruiserRTM) in a randomized complete block design (four replications). Five (2002) and six (2003) planting dates were examined for incidence of CFB feeding scars and Stewart's disease. Analyses revealed a reduction in incidence of the early wilt phase with delayed plantings, however, increased numbers of CFB's and rates of Stewart's disease were observed for these delayed plantings. Yield was also significantly reduced in delayed plantings. Delayed planting as a viable management tactic for Stewart's disease was deemed unfeasible. Furthermore, we examined forecasting models for Stewart's disease. Our goal was to increase pre-plant prediction accuracy at the county-level. We used binary logistic regression for modeling. The Stevens and Stevens-Boewe models were found to greatly under predict Stewart's disease occurrence, while the Iowa State Model improved forecasting. Also, two-factor models using air temperature (Iowa State Model, frequency of days with minimum air temp ≤ -6.7°C, sum mean monthly temperatures (Dec., Jan., and Feb.)), plus previous history of Stewart's disease in a county increased accuracy to 75-80%. Using receiver operating characteristic curves and an economic cost function for false predictions (positive and negative), a probability of 40% was defined for forecasting Stewart's disease. Overall, this thesis provides relevant new information in order to improve forecasting and management of Stewart's disease in Iowa.

Comments
Description
Keywords
Citation
Source
Copyright
Sat Jan 01 00:00:00 UTC 2005