Economics of Bt Maize Hybrids A new report on growing borer-resistant Bt maize hybrids in Ontario has indicated that growers should not rely on Bt genetics for a healthier bottom line every year. Tracy Baute, a University of Guelph researcher hired through a Novartis grant to study Bt corn, produced the report as part of her MSc. According to Baute "you have to look at Bt as an insurance policy. You won't get a return on investment unless there's heavy corn borer pressure." Ontario corn growers have planted 700,000 acres of Bt hybrids this spring, which represents about one-third of the crop according to OMAFRA corn specialist Greg Stewart. According to the report, the cost can be hard to pinpoint. On average, seed premiums work out to $10 to $14 per acre, depending on seeding rate and the deal offered by specific companies. Thus, seed companies are likely to earn $8 to $10 million extra each year from corn sales. Since Bt is new - and most Bt seed is only available in higher-priced elite and introductory hybrids - growers buying Bt can pay an additional $5 to $15 or more per acre. Baute compared Bt hybrids with their non-Bt controls in 40 plots across Ontario in 1996 and 1997. In addition, popular conventional hybrids adapted to each area were also included. Baute's strongest conclusion is that Bt works. She rates its effectiveness for preventing boring damage by European corn borers as at least 96%. Hybrids protected with Bt had fewer broken stalks and damaged ears. Baute was cited as saying they also had less ear rot and fewer mouldy kernels, adding, "the difference was great enough that it can make sense for a swine producer to go for Bt, whether there's a yield advantage or not." During the 2-year study, Baute found the Bt hybrids outyielded their non-Bt twins by 4%. However, the yield responses were sporadic. In 1996, borer pressures in the extreme southwest were intense, and some Bt-protected hybrids gave yield increases of 10%. In central and eastern Ontario, there were few if any extra bushels. In contrast, in 1997 there was little response in the southwest and big gains in the east. Baute plugged her results into a computer, and, based on seed premiums of $10 to $14 per acre and corn prices of $2.25 to $3.70 per bushel, she has concluded that growers can expect Bt to pay for itself one year in three. Her studies suggest a field needs an average 16 cm of tunnelling per plant in order to pay the premium cost. Baute's conclusions aren't out of line with tests by the seed companies. Pioneer Hi-Bred agronomist Tim Welbanks has pointed out that an intensive two-year research project in the northeastern corn belt produced average yield benefits of 8.8 bushels per acre with Bt hybrids. Most of the gains came in 1997, however, with little response in 1998 because of low borer numbers. Welbanks was quoted as saying, "the Guelph study is probably pretty realistic. As long as borer pressures are so hard to predict, you do have to look at Bt as insurance....it isn't going to pay every year." Baute has also cautioned growers to keep an eye on the yield potential of non-Bt hybrids. While in her trials the Bt hybrids outyielded their non-Bt twins, they rarely outyielded good conventional hybrids for the area. July 1999 -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] Archive: http://www.mail-archive.com/[email protected]/
