European Corn Borer Management in Field Corn: A Survey of Perceptions and Practices in Iowa and Minnesota

The European corn borer (Ostrinia nubilalis Hübner) is a major pest of field corn (Zea mays L.) in the midwestern states. In 1991, an outbreak of this insect caused yield losses as high as 32.6 bo/acre in Iowa and averaged 14 bu/acre in Minnesota. Following this pest outbreak, a questionnaire was developed to: (i) assess how farmers and agribusiness professionals perceive the crop production risks posed by European corn borer, and (ii) explore how these perceptions are reflected in management options they use or recommend. Fanners and agribusiness professionals completed 851 surveys. The survey results provided insights into yield loss perceptions, management tactics used, and research needs for European corn borer management. Economic yield losses caused by European corn borers during the first and second generations, respectively, were thought to occur only by 65 to 69% of farmers, 78 to 81% of ag-chemical professionals, 84 to 89% of crop consultants, and 68 to 70% of educator/agronomists. Respondents that perceived economic losses caused by European corn borers thought that the average loss was 153 to 16.6 bu/acre during the first generation and 15.2 to 18.1 bu/acre during the second generation. Although two-thirds of the farmers perceived the European com borer as a serious pest, only 35% had ever scouted their fields and used economic thresholds, and only 28% had ever used an insecticide to control the pest Farmers' primary and secondary options for managing the European corn borer or reducing yield losses were to harvest the fields early before ears drop onto the ground (63.4%) and to plant hybrids with known resistance (39.0%), respectively. In contrast, scouting and using economic thresholds was the primary recommendation from ag-chemical professionals (68.3%), crop consultants (88.5%), and educator/agronomists (54.0%). The second most common recommendation was using an insecticide by ag-chemical professionals (57.9%) and educator/agronomists (41.4%), whereas crop consultants were more likely to suggest early harvest to prevent ear droppage (73.8%). The survey results suggest that many farmers don't manage European corn borer because of historic inaction, hidden yield losses, reluctance to scout, logistical burnout, capital doubts, cultural competition, insecticide concerns, and a failure to recognize the problem. The results also suggest a strong need to educate farmers and agribusiness professionals regarding biology, crop damage, and management options for the European corn borer. Problem and Literature SummaryThe European corn borer is a perennial and serious pest of field corn. A single European corn borer can potentially reduce grain yields by 5.9%. An outbreak of this insect occurred in 1991 and field losses of 32.6 bu/acre, were documented in Iowa. Yield losses in Minnesota of 11 and 16 bu/acre, were recorded for the first and second generations, respectively, of this insect. Management options for reducing yield losses fiom this insect include planting date, hybrid resistance or tolerance, insecticides, early harvest, field scouting and using economic thresholds. Iowa and Minnesota farmers have been passive in limiting losses from European corn borer despite the availability of management options. For example, during the 1991 outbreak, less than 5% of Minnesota corn acreage was treated with insecticides, despite losses averaging 14 bu/acre. Why is there such a stark contrast between economic loss and management investment? To answer this question we decided to survey the perceptions, attitudes, and management practices of farmers, and their agricultural advisors, on European corn borer. We developed a survey with two objectives: (i) assess how farmers and agribusiness professionals perceive the production risks posed by European orn borer, and (ii) explore how these perceptions are reflected in the management options they use or recommend. The information from this survey could be used to modify or enhance extension educational programs focusing on integrated pest management of this insect. Study DescriptionA written survey with mostly close-ended questions was designed to explore perceptions and practices of farmers and agriculture professionals regarding European corn borer in field corn. The nonrandom survey was distributed during 1991–1992 to all participants at educational programs conducted by either Iowa State University Extension or Minnesota Extension Service. These surveys were completed at the beginning of each extension meeting so that responses would not be influenced by program content. Participants completed 851 surveys and their responses were divided into four broad occupational categories: farmer, ag-chemical professional, crop consultant, and educator/agronomist. Applied QuestionsDo farmers and agribusiness professionals perceive that the European corn borer can cause economic yield losses? Do farmers and agribusiness professionals perceive that the European corn borer can cause economic yield losses? PercentageCorn borerAg-chemicalCropEducator/generationResponseFarmerprmofessionalconsultantAmonomistFirstyes65818968no9568don't know2614524SecondYes69788470no6347don't know25191223For farmers and agribusiness professionals who believe European corn borers cause yield loss, how much loss (bushels ±SE per acre) occurs during an average year from European corn borers? For farmers and agribusiness professionals who believe European corn borers cause yield loss, how much loss (bushels ±SE per acre) occurs during an average year from European corn borers? Corn borerAg-chemicalCropEducator/generationFarmerprofessionalconsultantAgronomistFirst15.3±0.615.3±0.716.6±0.916.3±1.3Second15.2±0.617.5±0.815.5±0.918.1±1.7What are the primary and secondary management tactics used by farmers and recommended by agribusiness professionals to manage European corn borers? Farmers' primary and secondary options were to harvest the fields early before ears drop onto the ground (63.4%) or to plant hybrids with known resistance (39.0%). In contrast, scouting and using economic thresholds was the primary recommendation from ag-chemical professionals (68.3%), crop consultants (88.5%), and educators/agronomists (54.0%). The second most common recommendation was using an insecticide by ag-chemical professionals (57.9%) and educator/agronomists (41.4%)' while crop consultants were more likely to suggest early harvest to prevent ear droppage (73.8%). What areas of research should entomologists study to help farmers and agribusiness professionals better manage European corn borers? What areas of research should entomologists study to help farmers and agribusiness professionals better manage European corn borers? Categorynplant resistance68scouting/sampling28biological control/biological insecticides19news alerts and education18insecticide performance16economic thresholds14damage/yield loss relationships8cultural management4biological/environmental factors3What do the results of the survey suggest for extension educators? The results of this survey indicate that many farmers and agribusiness professionals involved with the production of field corn seriously underestimate the crop-damaging potential of the European corn borer. There is a strong need for continued and expanded education of farmers and agriculture professionals in Iowa and Minnesota regarding the biology, damage potential, and management of this insect. Maximum economic benefits for the farmer cannot be achieved until proper management of the European corn borer is integrated into the corn production system.