Lincoln, Nebraska
May 9, 2008
As planting season progresses,
it's important corn growers review current requirements for use
of Bt corn hybrids, a University of
Nebraska-Lincoln entomologist says.
As part of corn companies' registration of these hybrids with
the Environmental Protection Agency, resistance management
plans, including planting a non-Bt hybrid refuge area on each
farm, are required, said Bob Wright, UNL Extension entomologist.
"These plans are designed to prolong the effective life of these
important tools we have for corn insect management," Wright
said.
Growers should have signed an agreement with their seed company
and received written materials describing the Bt corn resistance
management plan associated with their hybrids, he said.
Specifics of resistance management plans vary somewhat dependent
on whether the hybrid is active against European corn borer,
corn rootworm, or stacked to contain both Bt types.
"A non-Bt hybrid refuge must be planted on each farm, containing
at least 20 percent of the corn acres on the farm," Wright said.
"The refuge must be treated similarly to the Bt corn plantings,
including rotational history, irrigation, etc."
For example, if the Bt corn field is corn after corn and
irrigated, then the refuge also should be.
Some differences exist between refuge requirements for different
types of Bt corn hybrids. These include:
- Bt corn hybrids active
against European corn borer, such as YieldGard Corn Borer,
Herculex I, Agrisure CB, must have a refuge planted no
farther than one-half mile from the Bt corn field.
- Bt corn hybrids active
against corn rootworms, such as YieldGard RW, YieldGard VT,
Herculex RW, Agrisure RW, must have the refuge planted
within the Bt corn field or in a field immediately adjacent
to the Bt corn field.
- If the Bt corn hybrid
contains Bt proteins effective against both corn rootworms
and European corn borers, such as YieldGard Plus, YieldGard
VT Triple, Herculex XTRA, Agrisure CB/RW, the refuge
requirements for corn rootworms must be followed.
"Growers need to take the time and
keep good records of which hybrids are planted in which fields
and ensure that the appropriate refuges are planted for each Bt
corn field that they plant," Wright said. "Good records will be
useful if growers are inspected for their compliance with the
registration requirements for Bt corn." |
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