Soybean transpiration, vegetative morphology, and yield components following simulated and actual insect defoliation

Soybean response to simulated green cloverworm (Plathypena scabra (F.)) (GCW) defoliation was investigated in several experiments from 1980 to 1983. The primary goals of this research were: (1) to assess the fidelity of simulation methods to actual insect defoliation for one basic physiological process, transpiration; (2) to determine if soybean response to defoliation varies between simulation methods; and (3) to elucidate the general effects of defoliation at full bloom on soybean growth, development, yield, and yield components;Water loss from potted soybean after defoliation by simulation methods and actual insects demonstrated significant, but transitory, differences during the first 16 hours. Total water loss over three days did not differ between simulated and actual insect defoliation. Therefore, simulation methods produced acceptable fidelity in soybean water-loss to actual insect defoliation;Simulation methods elicited different responses to defoliation. Each component of a simulation method, technique and temporal pattern, affected remaining leaf area, height, yield, and yield components. Punch-defoliated plants possessed less leaf area, height, and yield than pick-defoliated plants. One-day defoliation resulted in more leaf area, taller plants, and greater yields than either insect-model or equal defoliation. Yield differentials between methods were sufficiently large to significantly affect yield-loss estimates and economic injury levels (EILs);Simulated GCW defoliation at full-bloom (R2) produced linear reductions in leaf area, height, lodging susceptibility, and yield. Defoliation reduced leaf area in nodes 6-11, but reduced yields in nodes 4-9. This downward shift, presumably, involved downward translocation from upper undefoliated leaves. Defoliation primarily reduced yields through decreased pod and seed number and, secondarily, through smaller seed size;The EIL for first generation GCW larvae was established at 298,500 larval equivalents per ha or 23 per m of row (76 cm row width). Comprehensive EILs, reflecting moisture stress on the crop, were also derived. A general theory on incorporating survivorship information into economic thresholds was developed and illustrated using the GCW in Iowa soybean

Estimating the Benefits of Bt Corn and Cost of Insect Resistance Management Ex Ante

This paper estimates farmer benefits for corn rootworm (CRW) active Bt corn and costs of complying with Environmental Protection Agency insect resistance management requirements. The estimates are obtained from farmer survey data that were collected in Minnesota in 2002, just prior to the commercial releases of CRW Bt corn. Benefit estimates range from $14 to$33.4 million, while compliance cost estimated range from $3.5 to$8.7 million depending on whether or not CRW Bt corn also controlled the European corn borer and whether of not it was approved for sale in major export markets.Bt corn, compliance costs, corn rootworm, insect resistance management, willingness to pay, Crop Production/Industries,

Conducting public-sector research on commercialized transgenic seed: In search of a paradigm that works

Public-sector scientists have a mandate to independently evaluate agricultural products available to American farmers on the open market, whereas the companies that sell the products must protect their intellectual property. However, as a consequence of the latter concern, public scientists currently are prohibited by industry-imposed restrictions from conducting research on commercialized transgenic seed without permission of the company. Industry acknowledged the seriousness of the problem after public warnings by a large group of entomologists to EPA and scientific advisory panels that the assumption of independence of public-sector studies on these products is no longer valid under current restrictions. Both industry and public scientists are working to find an amicable, mutually-acceptable solution. Recently, the American Seed Trade Association brokered a draft set of principles designed to protect the legitimate property rights of companies while allowing public scientists independence to conduct most types of research on their commercialized products without the need for case-by-case agreements. While there are a number of potential pitfalls in implementation of the principles across companies, this effort represents a major step forward, and there is reason for optimism that this approach can be made to work to the benefit of industry, public scientists, and the American public

Biotechnology and the European Corn Borer: Measuring Historical Farmer Perceptions and Adoption of Transgenic Bt Corn as a Pest Management Strategy

A 3-yr, multi-state survey of farmers who had planted transgenic Bacillus thuringiensis (Bt) corn was conducted to evaluate perceptions of Bt corn performance and its utility as a management option for European corn borer, Ostrinia nubilalis (Hu¨ bner). A questionnaire was sent to farmers in Illinois, Iowa, Kansas, Minnesota, Nebraska, and Pennsylvania who had grown Bt corn during the growing seasons of 1996, 1997, or 1998. There were 7,427 usable questionnaires returned with the following response percentages: 1996 (42.1%), 1997 (35.0%), and 1998 (22.6%). Adoption rates, based on percentage of acreage planted to Bt corn, increased dramatically from 1996 (10.5%) to 1998 (40.7%). The states growing the highest percentage of Bt corn were Minnesota, Iowa, and then Nebraska. However, Illinois, was adopting Bt corn at the fastest rate. Historical use of insecticides did not inßuence the adoption of Bt corn. In addition, of those farmers who used insecticides to control European corn borer, the percentage that decreased their use of insecticides nearly doubled from 13.2% (1996) to 26.0% (1998) over this 3-yr period. The primary reason farmers planted Bt corn was to eliminate the yield loss caused by European corn borer. Scouting for European corn borers decreased from 91% (scouting 2.2 times a year) in 1996 to 75% (scouting 1.8 times a year) in 1998. The percentage of farmers not scouting for European corn borers increased from 9.6% (1996) to 25% (1998). Most farmers believed yields of Bt hybrids were either similar to or greater than the yields of non-Bt hybrids. Minnesota farmers perceived the greatest yield advantages. Farmers are becoming more aware of insect resistance management guidelines; however, they also clearly show preferences for having the ßexibility to use different spatial plantings of Bt and non-Bt corn. Finally, after having planted Bt corn and obtained excellent control of European corn borer, most farmers believed that this insect had been causing more yield loss than they previously had suspected in their non-Bt corn. The data represented here provide an historical foundation for how transgenic Bt corn was used by farmers during the Þrst 3 yr of commercial availability, their initial perceptions on the performance of this technology, and their attitudes regarding management of the European corn borer

Soybean transpiration, vegetative morphology, and yield components following simulated and actual insect defoliation

Soybean response to simulated green cloverworm (Plathypena scabra (F.)) (GCW) defoliation was investigated in several experiments from 1980 to 1983. The primary goals of this research were: (1) to assess the fidelity of simulation methods to actual insect defoliation for one basic physiological process, transpiration; (2) to determine if soybean response to defoliation varies between simulation methods; and (3) to elucidate the general effects of defoliation at full bloom on soybean growth, development, yield, and yield components;Water loss from potted soybean after defoliation by simulation methods and actual insects demonstrated significant, but transitory, differences during the first 16 hours. Total water loss over three days did not differ between simulated and actual insect defoliation. Therefore, simulation methods produced acceptable fidelity in soybean water-loss to actual insect defoliation;Simulation methods elicited different responses to defoliation. Each component of a simulation method, technique and temporal pattern, affected remaining leaf area, height, yield, and yield components. Punch-defoliated plants possessed less leaf area, height, and yield than pick-defoliated plants. One-day defoliation resulted in more leaf area, taller plants, and greater yields than either insect-model or equal defoliation. Yield differentials between methods were sufficiently large to significantly affect yield-loss estimates and economic injury levels (EILs);Simulated GCW defoliation at full-bloom (R2) produced linear reductions in leaf area, height, lodging susceptibility, and yield. Defoliation reduced leaf area in nodes 6-11, but reduced yields in nodes 4-9. This downward shift, presumably, involved downward translocation from upper undefoliated leaves. Defoliation primarily reduced yields through decreased pod and seed number and, secondarily, through smaller seed size;The EIL for first generation GCW larvae was established at 298,500 larval equivalents per ha or 23 per m of row (76 cm row width). Comprehensive EILs, reflecting moisture stress on the crop, were also derived. A general theory on incorporating survivorship information into economic thresholds was developed and illustrated using the GCW in Iowa soybean.</p

Farmers’ perspectives on resistance in western corn rootworm to CRW-Bt corn in Midwest USA

Resistance in western corn rootworm to transgenic corn hybrids was first confirmed in 2011 in Midwestern USA, and threatens their continued use. Farmers are often the first line of resistance detection, so their understanding and attitudes toward this issue are critical for improving resistance management. We conducted telephone focus groups during 2013 with farmers who had experienced rootworm resistance. There were four stages in dealing with unexpected rootworm injury: Awareness of a problem, diagnosis, confirmation, and recommendations. Most farmers discovered the problem themselves, but this usually happened too late in the growing season to limit yield loss. Once aware of a problem, farmers first sought help diagnosing the problem from their seed dealer, chemical rep, and/or crop consultant. They considered the problem to be a significant one, both because of its severity and suddenness, and were concerned about their difficulty in obtaining a correct diagnosis. They eventually used extension entomology specialists to confirm the diagnosis. Farmers gathered recommendations from independent consultants, input suppliers, and extension and indicated that they would aggressively deal with the problem, because they were not sure of what would work to protect their crop. They recommended that public extension put more emphasis on increasing awareness of the problem, assessing the extent of the problem and being an unbiased source of information. However, farmers were unlikely to report rootworm injury if the perceived barriers to reporting outweighed the perceived incentives. These barriers were emotional ones, including being unsure who to trust, fear that reporting will be time-consuming, and shame that they did something wrong. The incentive was access to credible advice. They did not automatically acknowledge the broader social benefits of reporting. Thus, extension probably needs to be explicit about these broader benefits to obtain information about the extent of the problem. With the conflicting demands and multiple information sources, it will be a challenge for extension to involve farmers to improve resistance monitoring and management

FARMER DEMAND FOR CORN ROOTWORM BT CORN: DO INSECT RESISTANCE MANAGEMENT GUIDELINES MATTER?

Farmer adoption of Bt corn and compliance with insect resistance management (IRM) regulations will influence the success of these regulations. The purpose of this paper is to use farmer survey data to estimate the demand for new corn rootworm Bt corn and the cost of complying with proposed IRM regulations

Estimating the Benefits of Bt Corn and Cost of Insect Resistance Management Ex Ante

This paper estimates farmer benefits for corn rootworm (CRW) active Bt corn and costs of complying with Environmental Protection Agency insect resistance management requirements. The estimates are obtained from farmer survey data that were collected in Minnesota in 2002, just prior to the commercial releases of CRW Bt corn. Benefit estimates range from $14 to$33.4 million, while compliance cost estimated range from $3.5 to$8.7 million depending on whether or not CRW Bt corn also controlled the European corn borer and whether of not it was approved for sale in major export markets

Farmers’ perspectives on resistance in western corn rootworm to CRW-Bt corn in Midwest USA

Resistance in western corn rootworm to transgenic corn hybrids was first confirmed in 2011 in Midwestern USA, and threatens their continued use. Farmers are often the first line of resistance detection, so their understanding and attitudes toward this issue are critical for improving resistance management. We conducted telephone focus groups during 2013 with farmers who had experienced rootworm resistance. There were four stages in dealing with unexpected rootworm injury: Awareness of a problem, diagnosis, confirmation, and recommendations. Most farmers discovered the problem themselves, but this usually happened too late in the growing season to limit yield loss. Once aware of a problem, farmers first sought help diagnosing the problem from their seed dealer, chemical rep, and/or crop consultant. They considered the problem to be a significant one, both because of its severity and suddenness, and were concerned about their difficulty in obtaining a correct diagnosis. They eventually used extension entomology specialists to confirm the diagnosis. Farmers gathered recommendations from independent consultants, input suppliers, and extension and indicated that they would aggressively deal with the problem, because they were not sure of what would work to protect their crop. They recommended that public extension put more emphasis on increasing awareness of the problem, assessing the extent of the problem and being an unbiased source of information. However, farmers were unlikely to report rootworm injury if the perceived barriers to reporting outweighed the perceived incentives. These barriers were emotional ones, including being unsure who to trust, fear that reporting will be time-consuming, and shame that they did something wrong. The incentive was access to credible advice. They did not automatically acknowledge the broader social benefits of reporting. Thus, extension probably needs to be explicit about these broader benefits to obtain information about the extent of the problem. With the conflicting demands and multiple information sources, it will be a challenge for extension to involve farmers to improve resistance monitoring and management.This article is published as David A. Andow, Robert J. Wright, Erin W. Hodgson, Thomas E. Hunt and Kenneth R. Ostlie. "Farmers’ perspectives on resistance in western corn rootworm to CRW-Bt corn in Midwest USA." Journal of Agricultural Extension and Rural Development 9, no. 3 (2017): 27-38. doi: 10.5897/JAERD2016.0827.</p