Northeast Region IPM Grants Projects Funded, FY 2001

Project Title:

Incorporating Bt-corn Hybrids into IPM Programs for Field Crop Farmers in the Northeastern United States
 

*Award shown is total amount to be used over the course of the project term.

Executive Summary

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The European corn borer (ECB) and corn rootworm are the two most important insect pest attacking field corn in the Northeast United States. In 2000, approximately 3.38 million acres of corn were grown in the Northeast with a value of about $866 million. It is estimated that injury from ECB feeding reduces corn yield by 13%, costing Northeast U.S. farmers $112.6 million per year in lost yield.
Amazingly with this magnitude of loss, less than 1% of cornfields in the Northeast were treated to control ECB populations prior to the introduction of Bt-corn hybrids. This attitude about treatment to protect the crop, however, was not unfounded. Insecticide programs were expensive ($15 to $20 per acre per application), difficult to time properly, and seldom provided economic returns. The introduction of Bt-corn offered a relatively low cost alternative that was highly effective at controlling the pest. In 2000, it was estimated that 20 to 30% of all corn acreage in the United States was planted to a Bt-corn hybrid. This rate of adoption of a new technology has been unprecedented in agricultural history. Bt-corn hybrids have been shown to provide good yield protection when ECB populations are at moderate to high densities. At low densities, however, the economic value of Bt-corn has been questionable. In many cases, the non-Bt hybrids have equaled or surpassed the yield of Bt-hybrids when ECB densities are low. A major question is whether the economic value of the technology justifies this level of adoption in the Northeastern U.S. In addition, significant controversy has been generated about non-target effects of Bt-corn on organisms and potential human health risks.
Because this variation in yield performance of Bt-hybrids has been linked to ECB density fluctuations, it is imperative that good data on frequency of infestation level be collected over time and geographic locations for the Northeast region. In addition, damage-loss functions for ECB on Bt and non-Bt hybrids must be established to estimate potential impacts once the frequency of infestation levels in the Northeast have been quantified. Hybrid testing plots using side-by-side comparisons of Bt-hybrids, their near isoline, and lead conventional hybrids will provide information on Bt-hybrid performance in the Northeast. Information from these studies will be used to calculate the economic value of Bt-hybrid use in IPM programs of Northeast U.S. farmers. The results will be published in an extension bulletin titled, "The Economic Value of Bt-corn Hybrid Technology in the Northeastern United States". In addition, demonstration plots will be established and used to train county agents, seed industry representatives, ag-input dealers, and farmers about ECB biology and the proper use of Bt-corn.
By providing unbiased information on the benefits of Bt-corn hybrid technology, strategies for use of these new and valuable non-pesticide based technologies will be formulated. Results of the proposed research will provide timely, localized and relevant information that extension agents and industry representatives in the region are requesting. Farmers identified research on the use of genetically altered crops for pest management as a top priority in the Northeast IPM Research and Extension Priority Needs Assessment of 1996. In addition, they listed the investigation of non-pesticide alternatives and demonstration programs for new technologies as high priorities. Quality information from this project will allow us to develop a proactive extension leadership position in the Northeast and help growers effectively utilize the technology.

THE PROBLEM, BACKGROUND, AND JUSTIFICATION

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The two most significant pests of field corn in the Northeastern United States are the corn rootworm (CRW) complex, Diabrotica virgifera virgifera (western Corn rootworm) and D. barberi (northern corn rootworm), and the European corn borer (ECB), Ostrinia nubilalis (Hubner). The corn rootworm complex is estimated to cause a 6.5% loss in corn yield annually because of its root-feeding behavior (Grey 1999). The European corn borer is also estimated to cause an average 6.5% annual loss in yield from stalk tunneling, ear droppage, and disease introduction (Calvin 1995). In 2000, approximately 3.38 million acres of corn were grown in the Northeast with an estimated value of about $866 million (NASS 2000). It is estimated that the combined yield lost from corn rootworm and ECB feeding is 13.0%, when the pests are left uncontrolled. This is a potential $112.6 million per year loss in income to farmers in the Northeast states. Nationally, protection against these two pests is estimated to be worth $2.6 billion. For this reason, seed technology companies have invested heavily in research to develop genetically modify corn hybrids that incorporate the Bacillus thuringiensis endotoxin genes for resistance against these two major pests.
In 1996, the first transgenic corn hybrids, Zea mays L., for European corn borer management were commercially released by Ciba Geigy (currently Novartis) and Mycogen (Event - Bt176). This was followed in 1997 by the release of two Monsanto events (MON 810 and Bt11). All of these original events were based on the Cry1A(b) strain of Bacillus thuringiensis subsp. Kurstaki (Bt), an entomophagous bacteria. More recently Dekalb and Aventis released hybrids from events that use Cry1A(c) and Cry9c protein toxins, respectively. Grower adoption of these Bt based technologies has been extemely rapid, with 20 to 25% of all cornfields in the United States planted to Bt-corn hybrids in 2000 (Paula Davis, personnel communication). Similar rates of adoption have been documented in the Northeast region (Rice et al. 1997 & 1998). This rate of technology adoption is unprecedented in history. Pioneer International is hoping to release hybrids from a new event that uses a Cry1F protein toxin in the next few years. These hybrids will have a broader spectrum of activity against Lepidopterous pests of corn, such as black cutworm.
Corn rootworm resistant corn hybrids have yet to be approved by the EPA. However, Monsanto is hoping for a 2001 growing season registration and Pioneer International is hoping for registration of its event by 2003. The two leading CRW events have incorporated the gene from Bacillus thuringiensis subsp. tenebrionis (Cry 3B(b)). When commercially released, these toxins will be sold either as a single gene construct or as a stacked construct with a European corn borer cryprotein for broader spectrum protection. This will present farmers with a difficult decision concerning which type of corn hybrid to plant. A farmer will need to decide whether he/she needs one or both genes in a hybrid based on their anticipated pest pressure.
Although these two pests are estimated to cause similar losses in yield, effort to control corn rootworm has been substantially higher in the Northeast. Crop Management Association records for Pennsylvania between 1990 and 2000 suggest that between 35 and 40% of cornfields are treated with a soil insecticide to prevent corn rootworm injury, while > 1% of fields were treated with an insecticide for European corn borer prior to the commercial release of Bt-corn (Calvin et al. 1992). Similar levels of soil insecticides are used in other Northeast states. Because of the percentage of fields currently treated with a soil insecticide, seed technology companies optimistically anticipate >50% adoption of CRW transgenic corn hybrids. At an average cost of $15.00 per acre for a soil insecticide treatment, farmers in the Northeast are currently spending approximately $17.7 to $20.3 million annually to manage corn rootworm. Seed technology companies indicate that corn rootworm transgenic corn will have a competitive technology fee similar to the cost of a soil insecticide. Currently, the technology fee for European corn borer is between $8 and $10 per acre. For a CRW and ECB stacked hybrid, the total technology fee could be as high as $23.00 to $25.00 per acre, increasing the cost of a unit of seed by $65 to $70 (2.85 acres @ 28,000 seeds per acre). Given the current 25% adoption rate of Bt-corn in the northeast, farmer are spending approximately $6.8 to $8.5 million to control European corn borer. If in the future, farmers purchase corn hybrids with both ECB and CRW resistance genes for every cornfield currently treated for corn rootworm, they may spend between $27.2 to $33.8 million annually to manage both pests. The big questions are what percentage of cornfield will gain an economic yield and/or quality advantage through the use of both genes, what percentage of fields will gain economically for only one gene, and what percentage of fields will gain no economic advantage from either gene, and our there more economically viable non-GMO management alternatives for each pest.
The Seed Technology Industry's initial expectation of high market penetration has recently been setback because of the growing controversy surrounding the economic value and potential health and environmental problems identified with the technologies. Originally, the Bt-gene technology was sold as a human health and environmentally benign pest management tactic. Safety issues of Bt-corn hybrids are non-target effects on other non-pest species (monarch butterfly, lacewings, natural enemies of ECB, etc), the presence of antibiotic markers in some Bt-corn hybrids, potential protein allergens, and the release of the protein toxins into the soil during stalk and root system degradation. The scientific basis for many of these claims is preliminary or questionable, but these issues have had a great impact on the general public's perception of genetically modified organisms (GMOs). Because of the great amount of recent negative publicity and consumer perception of GMO's, future markets for the technology are uncertain and farmers are faced with decisions about whether they should grow Bt-corn hybrids.
Prior to the development of Transgenic Bt-hybrids, Bacillus thuringiensis subs. Kurstaki was used as a biological control tactic for insects in the order Lepidoptera (moths and butterflies;since the 1970's). It was sold under numerous trade names and applied as a liquid or granular formulation. Bt was widely adopted by the organic food production industry because of its specificity to insects in the order Lepidoptera, which prevented mortality to valuable natural enemies of other insect pests, its low mammalian toxicity (near zero), and its low toxicity to other taxa (groups) of animals. They also liked the fact that Bt is a naturally occurring soil bacterium. Ironically, the organic food industry has been against the wide spread used of genetically altered crops, which incorporate the gene for Bt toxin production. They fear that throught high adoption of Bt-corn hybrids ECB and other major pests will become resistant to the toxin and eliminate the use of Bt as a pest control tactic for organic producers. They are also concerned about the consumer's willingness to purchase organic products that are genetically engineered.
The use of liquid and granular formulations of Bt in traditional crop production systems, however, has been limited because the product breaks down rapidly under UV light, only provides moderate to low levels of pest control in many cases compared to traditional insecticides, and multiple applications are typically needed for adequate control making it a high cost alternative.
These shortcomings of Bt spray and granular formulation were eliminated when the gene responsible for producing the Bt endotoxin was incorporated into the genome of the corn plant. Once incorporated as part of the plant's own DNA, the plant manufactures the toxin continually over its growth period at concentrations 100 to1000 fold greater than needed to kill 99% of the ECB larvae. This delivery mechanism assured excellent protection of the plant from the insect over its entire growing period. The gene also produced the toxin and not the pro-toxin that was sold as the active ingredient in the spray and granular formulations, eliminating the time required to convert the non-toxic pro-toxin into its toxic form in the alkaline mid-gut of the insect. Using the plant as the toxin delivery system reduced the technology's cost and greatly increased its efficacy.
As mentioned earlier in the paper, prior to the release of these genetically modified corn hybrids few farmers used insecticides as a control tactic against the Euorpean corn borer. So why the high level of adoption of Bt-corn hybrids? To understand this major change in farmer's attitudes toward management of the ECB in the Northeast, it is important to understand the history and economics of ECB pest management. When the pest was first introduced into North America from Europe in the early 1900's, it devastated cornfields, completely eliminating any yield from the crop. From the 1930's to 1970's, the United States Department of Agriculture (USDA) imported and released many of the ECB's natural enemies from Europe (Jones 1927, Baker et al. 1949, Hudon et al. 1989). Several species successfully established in North America and continue to help regulate populations of the pest. Losey (1992) conducted a survey of overwintering ECB larvae in Pennsylvania and found mortality levels from parasitoids and diseases to be as high as 80% at some locations.
Besides importation and release of natural enemies, the USDA established the ARS Corn Insect Research Laboratory at Ankeny, Iowa to develop corn varieties and hybrids with resistance to the pest. Since this breeding effort was started, several mechanisms of resistance have been identified and incorporated into most field corn hybrids. Chemical factors included: 1) DIMBOA (2-4-dihydroxy-7-methoxy, 1,4-benzoxaxine-3-one), 2) a shealth and collar resistance factor, and 3) a first generation resistance factor (Guthrie 1988, Barry & Darrah 1991). Physical resistance factors included stiffer stalks with higher lignin and silicon concentrations and a general higher level of tolerance to feeding injury. The combination of these traditionally incorporated resistance factors has resulted in hybrids with an overall high level of tolerance to injury from the pest. In a Pennsylvania study, Pajerski (1990) showed that under good moisture conditions corn hybrids can tolerant up to six ECB larvae per plant without a measurable yield reduction. Godfrey et al. (1991) showed the relationship between moisture level and impact of ECB stalk tunneling. With today's hybrids, it is now uncommon to find more than an average of one or two ECB larvae per plant in a cornfield, compared to earlier in this century when 15 to 20 larvae per plant were common infestations. The large majority of fields have less than one larva per plant, while an average infestation of four or more larvae per plant is considered high. The introduction of Bt-corn is just another brick to complete the wall of corn plant resistance against the pest. The impact of Bt-corn in reality is relatively small in comparison to the substantial gains made historically through traditional breeding programs and importation and release of natural enemies to control the pest's populations.
Management of the pest has included a number of cultural practices, such as tillage, stalk shredding, burning of stalk residue, and adjustment of planting and harvest dates. A survey of Pennsylvania farmers indicated that 8.2, 5.2, 23.0, 53.9, and 7.3% used resistant hybrids, adjusted planting dates, adjusted harvest dates, did nothing, or used other tactics, respectively, to control ECB populations prior to the introduction of Bt-corn (Rice et al. 1997). When cultural and genetic tactics failed to keep ECB populations below economic levels, insecticides were the primary tactic used to rescue the crop. The value of an insecticide control program, however, was questionable in many areas across the pest's geographic range, particularly in the Northeast United States (Tollefson & Calvin 1994). Management using an insecticide program was cost effective only in the western fringes of the Corn Belt and along the eastern seaboard (Calvin 1995). Based on the economic analysis conducted by Calvin (1995), the average corn producer in the Northeast would lose $11.63 per acre using an insecticide approach to manage the pest. They estimated that only about 3.0 and 12.0% of cornfields have first and second generation ECB populations high enough to justify the cost and effort involved in implementation of an insecticide control program. With the lower cost of Bt-corn and its higher efficacy, the economic thresholds dropped considerably, increasing the percentage of fields with infestation levels above threshold to 39 and 75% for first and second generation ECB, respectively (Calvin 1995). This economic assessment of Bt-corn hybrid value, however, was based on the difference in yield and control performance of Bt-corn hybrids and near isolines. The economics of Bt-corn compared to conventionally bred elite hybrids has not been fully assessed.
Many researchers have investigated the impact of ECB on field corn yields. Patch et al. 1941 estimated that ECB larvae cause an average yield loss of 3% per borer per plant. Calvin et al (1998) established a functional relationship between growing degree-days remaining from harvest when ECB feeding occurred and percentage yield reduction for field corn grown in Kansas. ECB larval feeding was greatest when plants were infested during the blister stage, causing an average 5.6% loss per larvae. Bode and Calvin (1990) duplicated the study in Pennsylvania, but included two vegetative crop growth stages. In their study, the average percentage yield reduction per larvae was about 6.0%, 5.0%, 3.0% and 2.5% when plants were infested during the 10th leaf stage, 16th leaf stage, blister stage, and dough stages of development, respectively. A comparison of these studies shows that ECB injury differs under variable growing conditions. In Kansas where daily high temperature are commonly in the high 80's and 90's and atmospheric demand on the plant is high, the impact of ECB larval feeding during the blister stage is twice that seen in Central Pennsylvania under milder conditions. In the Northeast, conditions similar to Kansas may occur in the Delmarva regions of Delaware and Maryland, but not in other areas. Losses from ECB in most of the Northeast region would be more similar to those seen in Central Pennsylvania.
Several authors have reported that ECB stalk tunneling increases injury from stalk and ear rot organisms. Keller et al. (1986) reported that ECB not only provide a site of ingress of the Anthracnose stalk rot organism, but that the larvae can vector the fungus. Their results agreed with Christensen and Schneider (1950), Chaing and Wilcoxson (1961), and Jarvis et al. (1982 who all studied the interaction of stalk rot organisms. In other studies, no association was found between ECB tunneling and invasion of stalk rots (Hudon et al 1992, Carson and Hooker 1981, and Foot and Timmins 1983). Althought there are some differences in the literature, there does appear to be a clear relationship between insect damage to corn ears and development of ear rot and mycotoxins in general and this association has been documented for European corn borer in particular (Christensen and Schneider, 1950; Smith and White, 1988). Thus, not only does corn borer damage contribute to yield reductions but it also impacts grain quality. In the Northeast region, dairy farmers are concerned about the effect of mycotoxins in feeds and forages on milk production and herd health. In Vermont, some herd consultants estimate that 20% of their clients have problems that are either directly associated with or presumed to be mycotoxin related at any one time (Gotleib, 1997). Additionally, they state that nearly all clients have mycotoxin problems at least once in every five year period (Gotleib, 1997). The most commonly occurring mycotoxins appear to be deoxynivalenol and zearalenone.
Deoxynivalenol and zearalenone are produced by Gibberella zeae (Fusarium graminearum) the causal agent of Gibberella ear rot of corn (White, 1999). Fusarium verticillioides (syn F. moniliforme) and F. proliferatum are also commonly associated with corn and cause ear and kernel rots as well (White, 1999). These two fungi produce the fumonisin class of mycotoxins. Fumonisins are considered probable human carcinogens (IARC, 1993) and cause the fatal diseases porcine pulmonary edema and equine leukoencephalomalcia (Harrison et al, 1990; Marasas et al., 1988). Fumonisins are found in corn grown in Pennsylvania sometimes at levels that are a concern for sensitive species such as pigs and horses (Nelson, 1995). Recently, a study conducted in Iowa documented a reduction in fumonisin levels in Bt-corn as compared with non-Bt isolines over several growing seasons (Munkvold et al., 1999). If mycotoxin levels in corn are reduced with use of Bt corn in the Northeast this would provide an additional impetus to grow these varieties. However, if mycotoxin and ear rot control is not observed in the Northeast as it is in the Midwest then decisions on economic value to farmers should be made solely based on yield factors as described herein.
Despite all that is known about ECB feeding injury, considerable controversy still exist regarding the economic benefits of Bt hybrid use in the Northeast region. In public (university) testing programs, Bt hybrids have provided excellent control of the ECB but have not consistently yielded better than normal hybrids. In a study conducted at four locations in Pennsylvania between 1997 and 1998, the average yield of three Bt hybrids was four bushels per acre higher than the average yield of three normal hybrids. In another two-year study conducted on two different planting dates, a three bushel per acre yield advantage was found for Bt-hybrids planted early and during the typical planting period and an 11 bushel per acre advantage was found for delayed plantings (Roth et al., unpublished field test data). From this study, it was concluded that the value of the Bt-corn technology was greater for late planting dates, because these plantings are more susceptible to attack by second generation ECB. A New York silage study showed no yield benefit to Bt hybrids (Cox, 1998). In a two year Wisconsin study that compared some early introductions of Bt hybrids to their normal counterparts, the near Bt isolines yielded similarly in one year but 12 bushels per acre less in the second year. The authors of this study concluded that in the future, as Bt genes are introduced earlier in the breeding process, yield competitiveness of Bt hybrids will likely increase. Based on an average corn market value of $2.33 per bushel (National Crop Growers Association data) and a $10.00 per acre premium for the Bt-corn hybrid seed, the break-even yield increase needed to justify using the technology is about 4.3 bushels per acre. From the limited testing of Bt-corn hybrids, it appears that the technology has marginal value to Northeast farmers. Similar results have been seen from university tests conducted in mid-western Corn Belt states. It is this question about the benefits of Bt-corn hybrids for ECB management that makes this research essential. If Bt-corn hybrids infrequently provide economic value to the grower, than a grower purchasing a stacked Bt hybrid will be paying for an expensive corn rootworm program.
In contrast to public and university hybrid testing programs, the seed industry has been reporting larger yield benefits to the Bt-corn technology of between 7 and 15 bushels per acre over numerous comparisons of hybrids and their Bt counterparts. The seed industry, in fact, has criticized university data sources because of their general lack of multi-location testing of the same hybrids. They claim to have shown these large yield improvements from Bt-corn hybrids by aggregating large numbers of hybrid tests from across the United States. This approach, however, does not provide information on hybrid performance under variable environments and within specific geographic areas. Also because the seed industry has a closed-door policy about sharing their actual test procedures and results, it makes one suspicious of the data and whether they pick and choose the tests they want to publicize. The only commonality between university and seed industry finding is that the technology provides a higher return when ECB population densities are at moderate to high level.
From both university and seed industry trials, it is clear that the technology's economic value is tied to ECB population density. Over the last three years, ECB populations have dropped dramatically across the United States. In 1996 and 1997 when the new technology first hit the marketplace, ECB populations were at moderate to high levels. In 1998, weather conditions in the Northeast and Corn Belt states caused ECB populations to collapse. The spring of 1998 was warm and very wet. Very few farmers were able to plant during the typical planting period, so the majority of corn was planted two to three weeks later than normal. The warm spring weather, however, accelerated ECB development leading to an early adult emergence period relative to corn development. Spangler (1999) showed that ECB females do not deposit their eggs in cornfields until they reach the V5 (five leaf) stage of development. This behavior is an adaptation to prevent young larvae from being killed by the DIMBOA concentrations found in most commercial corn hybrids. In 1998, very few fields had reached the V5 stage of development when ECB females were looking for hosts to deposit their eggs. Consequently, adult and larval mortality was extremely high leading to a population collapse. A collapse in insect populations is quite common and many times occurs on a regular cycle. European corn borers population densities tend to fluctuate over about a seven-year cycle (Ostlie, unpublished long-term records of ECB densities in Minnesota). The level of ECB pressure increased slightly in 1999, but in general remained quite low. In 2000, average ECB densities increased slightly over 1999. Given this cyclic pattern of insect numbers, it is important that we quantify the changing densities of ECB in the Northeast and gain a historic picture of variation in densities. Many of the tests comparing Bt-corn verses conventional hybrid yields have been conducted during this period of extremely low pressure. Therefore, although the recent economics of Bt-corn have been questionable, over the long run they may be quite favorable to the technology.
Gaining a clear picture of Bt-corn's true economic value has been difficult. Early tests (prior to commercial release) only allowed comparisons of Bt hybrids and their near isolines because EPA regulations were designed to prevent escape of the Bt-gene (i.e. a 660 foot buffer around plots was required). These comparisons provided good information on the Bt gene's ability to protect the plant's yield potential, but not on how Bt-corn hybrids yielded compared to conventionally bred hybrids. Side-by-side comparisons of Bt-hybrids and top yielding conventionally bred hybrids were not possible until Bt-hybrids were commercially released in 1996 and 1997. Even after their release, many seed companies were reluctant to provide seed to university researcher to compare Bt and non-Bt hybrids. They argued that traditional hybrid testing procedures did not provide a good measure of the technology's performance, because Bt-corn hybrids should only be compared to near isolines and not other hybrids. In some cases, the companies were worried about a "Halo Effect", where late instar ECB were able to colonize Bt plants by moving between plots. The companies argued that the Bt-gene only protects the yield potential of that hybrid's genetics. Farmers, however, are interested in which hybrids consistently have the highest yield potential irrespective of the presence of ECB injury or the Bt-corn gene. Conventional hybrid testing programs in the region have frequently evaluated Bt hybrids in a separate test, making comparisons to normal lines impossible. When Bt lines have been included in hybrid testing programs, isolines are generally not present so it is difficult to estimate whether the performance differences are due to the Bt gene or the hybrid's overall genetic background. For this reason, there is a great need to implement hybrid test plots that directly compare Bt and conventional hybrid yield potential.
The continuing debate about the economic value of Bt-corn hybrids in the Northeast region is costing farmers potential profits and could cost even more when genes become stacked in a hybrid. If they are using Bt-corn hybrids and do not need them, then they are spending limited dollar resources unwisely. If Bt-corn truly has an economic value, then farmers should be using it to improve their profit margin. The debate on value of Bt-corn can only be ended through the collection of scientifically sound yield performance information, the collection of good ECB density information, and the establishment of damage-loss functions for the wide array of Bt and lead conventional hybrids. It is possible that the genetics used in Bt-corn hybrids may be more susceptible to ECB injury than the genetics of lead conventionally bred hybrids. Therefore, the degree of yield protection would be higher in Bt genetics versus non-Bt hybrid genetics. Farmers need answers to these important economic questions. Without this type of research, the uncertainty surrounding the use of Bt-corn will continue and farmers will continue to be in a very risky position when they choose to grow a Bt-hybrid.
Answers to the public's concerns about GMO's effects on non target organisms and human and livestock health are being addressed by the NC-205 regional research project and the National USDA Monarch Research Team. If any of the current concerns about negative effects on human health and the environment by Bt-corn are substantiated, then it will be important to have solid economic benefits information for comparison with risks of using the technology. Seed corn company rhetoric and/or limited university research trials will not provide a good scientific foundation to evaluate the economic benefit of GMO's. By providing more unbiased information on the benefits of Bt-corn hybrid technology this project will help formulate strategies for proper use of Bt-corn hybrid technologies. Results of the proposed research will provide timely, localized and relevant information that extension agents and industry representatives in the region have requesting. Farmers identified research on the use of genetically altered crops for pest management as a top priority in the Northeast IPM Research and Extension Priority Needs Assessment of 1996. In addition, they listed the investigation of non-pesticide alternatives and demonstration programs for new technologies as high priorities. Discussions with farmers at winter meetings and field days typically focus on GMO related issues. Quality information from this project will allow us to develop a proactive extension leadership position in the Northeast and help farmer's effectively utilize this new and important technology.

Objectives

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1. Assess yield performance of Bt-corn hybrids relative to near isoline and leading conventionally bred hybrids across multiple crop production zones of the northeastern region.

2. Compare the relationship between European corn borer larval numbers per plant and percentage yield reduction of lead conventional and transgenic corn hybrid near isolines.

3. Conduct a survey of first and second generation European corn borer densities (numbers per plant) across the region.

4. Assess the economic benefits of using Bt-corn hybrids, in an IPM program, versus conventionally bred lead hybrids.

5. Develop a publication on the economic value of Bt-corn hybrids in the northeastern United States and conduct in-field extension demonstrations of the technology.

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