Some farmers question YieldGuard's quality

DES MOINES, IOWA, September 5, 2004 -- CropChoice news -- Mike McGinnis, DTN, 09/03/04: Several producers have complained about severe lodging in fields planted to Monsanto's YieldGuard rootworm-resistant hybrids, which might be caused by surviving rootworms.

But a representative from Monsanto said the product is working fine - there are simply more rootworms this year than normal.

YieldGuard was introduced for commercial use in February 2003. More than 20,000 growers use YieldGuard on about 2 million acres, according to Monsanto statistics.

Along with complaints from farmers, University of Illinois entomologists who did field trials in Urbana, Dekalb and Monmouth found reason to write an article addressing the concerns of YieldGuard and the lodging of corn stalks in this year's crop.

Kevin Steffey, an extension specialist and professor of agricultural entomology in the department of crop sciences at the University of Illinois, told DTN lodging was severe in one of the three test plots.

"We had more damage in our plots than we or Monsanto expected to see," he said. "I don't have a handle on all the down corn, but we are not suggesting (YieldGuard) isn't working in fields.

"We are not suggesting it's (YieldGuard) not working."

The reason he wrote the report, Steffey said, is to give growers a heads-up about what's going on in fields planted to YieldGuard varieties.

"We needed to make people aware of the concern from many growers that said their rootworm YieldGuard corn was lodged," he said.

Steffey said he stresses the results of the University of Illinois study don't mean YieldGuard doesn't work, but he found it interesting that one of the three test fields had severe lodging and several customers complained they had lodging in their YieldGuard fields.

"We were only in a small set of fields in Illinois," he said. "Not all fields that were lodged were from rootworm damage, wind was involved."

Todd Degwoyer, Monsanto's corn trade technical manager, said the rootworm damage is a result of higher populations of rootworms this year than in the past.

"If you look at the data from the researchers, the rootworm damage they saw is still showing the product is working as well as any other protection out there," he said.

But Steffey said higher rootworm populations can't be the cause of the lodging or the reduced efficacy of the YieldGuard hybrid.

"It's bothersome when the excuse of too many insects is made," he said. "We have trials with a lot of pressure, so to tell the grower the product didn't work because of too much insect pressure isn't right. The label doesn't say this product will work unless there is heavy insect pressure."

In a recent survey, Monsanto found that 90 percent of farmers reported they were happy with YieldGuard Rootworm in 2004.

Degwoyer said most of the issues pertaining to YieldGuard Rootworm products centers around lodged corn in eastern Illinois.

"We have gone out to commercial fields and find the rootworm technology is working on insects but the lodging is from high winds and heavy rain," he said. "When you have a lot of growers using different practices there are just things you learn the first year out. It's tough when the rootworm damage is not consistent."

Steffey said this has happened in the past, so finding out why certain products perform better in field tests than in the actual field is the goal.

"This has happened with other products before, where it looked great during pre-market trials and then not so good after being sold commercially," he said. "We just need to find out why."

But a recent article written by Steffey on integrated pest management questioned whether resistance to YieldGuard Rootworm hybrids already occurred.

"We don't believe so," he said. "Keep in mind that YieldGuard rootworm hybrids were released commercially for the first time in 2003. It does not seem probable that rootworm resistance to the Bt protein has occurred this quickly.

"The FIFRA Scientific Advisory Panel (August 2002) suggested that the likelihood of resistance development within the first three years of commercialization is unlikely, regardless of refuge size."


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