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Genetically Modified Crops In Wisconsin: Bt Corn Down, Soybeans Up, UW-Madison Survey Shows

Herbicide-resistant soybeans are a hit with Wisconsin farmers, but corn that’s genetically modified to resist insect pests may have passed its prime in the state, an ongoing University of Wisconsin-Madison survey has shown.

Use of insect-resistant BT corn in Wisconsin probably declined in 2001, with 17 percent of growers saying they intended to plant it on about 430,000 acres, or 12.3 percent of the state’s corn acreage. Last year, 21 percent of growers planted Bt corn on 12.6 percent of the corn acreage, according to researchers with the Program on Agricultural Technology Studies at the UW-Madison”s College of Agricultural and Life Sciences. (The 2001 survey measured farmers” intentions, rather than actual use, because the survey was completed before the planting season.)

Bt corn varieties contain a gene from the bacterium Bacillus thuringiensis, which produces a protein that is toxic to certain insects that eat the corn, but harmless to people and livestock.

Bt corn’s performance has received mixed reviews, according to the PATS researchers. While 72 percent of users reported less pest damage than with conventional varieties, only 37 percent reported applying less insecticide. About 61 percent reported higher or much higher yields from Bt corn, but more than two-thirds also reported higher expenses. Fewer than half of the growers reported higher profits from Bt corn compared with conventional varieties.

Surveys in 2000 and 2001 showed that about 30 percent of farmers who had planted Bt corn in the previous year had not planted it in the next growing season. The Bt corn disadopters were more likely to report higher expenses and lower profits and yields than continuing users.

While Bt corn adoption may be falling, more growers are planting herbicide-resistant corn, the survey showed. About 18 percent of the respondents intended to plant HR corn in 2001, up from 11 percent in 2000 and 5 percent in 1998.

Growers have increased their use of herbicide-resistant soybeans every year since 1998. HR soybeans accounted for more than 65 percent of the state”s soybean acreage planted in 2001, up from 57 percent in 2000 and 16 percent in 1998. About 68 percent of Wisconsin soybean growers planted HR soybeans this year.

Growers say that HR soybeans allow better weed control, reduce overall herbicide use, and reduce the labor required to grow beans. When asked to compare HR soybeans with conventional varieties, nearly three-quarters of HR soybean adopters reported using less herbicide, and about two-thirds said they had lower or much lower expenses. Only 38 percent of adopters had higher yields, but 53 percent reported higher profits.

Growers who plant HR soybeans tend to plant them again. About 13 percent of 1999 adopters dropped HR beans in the 2000 growing season, and just 3 percent of 2000 adopters dropped them in 2001, the PATS survey showed.

“These data suggest that GMO soybeans are a significant part of the transformation of Wisconsin agriculture toward cash grain farming, and that HR soybeans will play an even more important role in Wisconsin agriculture in the future,” says study author Brad Barham.

“HR soybeans are essentially an ”input-reducing” technology, saving farmers both time and labor in weed management. Bt corn is more of a ”yield-enhancing” technology, but one with generally higher expenses,” he says. “The strong differences between farmer adoption practices and experiences with regard to Bt corn and HR soybeans suggest that GMOs are much more diverse in their costs and benefits than is widely appreciated.”

Farmers who decided to drop GM varieties cited production performance as the biggest factor influencing their decision. However, both Bt corn and HR soybean disadopters were more likely to cite marketing concerns as influencing their decisions to disadopt than were non-adopters who were asked why they had not chosen GM varieties.

The most important reason farmers gave for not adopting GM varieties was satisfaction with their current corn or soybean varieties. Next most important was lack of information about GM varieties. Marketing-related problems, such as lower prices and the need to segregate GM varieties, were also mentioned, but were not among the major reasons for non-adoption.

Fewer than 2 percent of the Bt corn adopters in the survey reported planting StarLink corn; those that did had no problems selling the corn as livestock feed. (StarLink corn is a genetically modified variety that has not been approved for human consumption in the United States. Last year, foods that may have contained StarLink corn were recalled in the United States, and Japan, a major corn importer, sharply cut its imports of U.S. corn after tests revealed traces of StarLink corn in food and animal feed products.)

PATS researchers have surveyed a randomly selected panel of corn and soybean growers each year since 1998, and completed a follow-up survey in winter and spring 2001. They have collected data from farmers who adopted, continued to use, or de-adopted GM crops, along with farmers who never planted GM varieties.

Doctoral candidate Lucy Chen is the lead author of this study, and PATS co-director Fred Buttel also participated. For a copy of the full report, “Update on the Adoption and De-Adoption of GMO Crop Varieties in Wisconsin,” contact Nancy Carlisle at (608) 265-2908.