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,"
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
"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
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."