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2-Plants: Only three Bt-corn events stay on U.S. registration list

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TITLE:  Developments in Bt corn for 2003
SOURCE: CropWatch News Services, University of Nebraska, USA
        Institute of Agriculture and Natural Resources Cooperative Extension
DATE:   Nov 15, 2002

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Developments in Bt corn for 2003

Transgenic corn hybrids that are resistant to insects (Bt corn) are no 
longer new, and most Nebraska corn producers have grown some of these 
hybrids, or at least are familiar with them.

There are, however, new Bt field corn events in development or that will be 
available soon. I would like to briefly discuss what events are available 
for 2003, what events have been discontinued, and what events are to become 
available shortly. Hopefully this will aid in hybrid selection for the 2003 
growing season.

First, what is an "event" with respect to Bt corn? An event is the 
successful insertion of a gene encoding a Bt protein into corn plant DNA. 
Different events vary in the type of Bt protein produced, the expression of 
the protein, and the target insect pest. Expression refers to where, how 
much, and at what plant stages the Bt protein is produced in the corn plant.

In October 2001, EPA finished a review of three Bt field corn events and 
approved registration of the events through October 15, 2008 (see table, 
below). These events will be in a variety of corn hybrids and offered 
through several seed companies. All are very efficacious against European 
corn borer. Two, Bt-11 and Mon810 (both under the trade name YieldGard), 
have been around for several years. The Cry1F event (Herculex I), however, 
is new for 2003 and also is efficacious against fall armyworm and black 
cutworm. Note that the events "suppress" some other caterpillars. If these 
other pests are your primary concern, the Bt hybrids may not satisfactorily 
control them.

Several commercial products have been discontinued. Their registrations 
have either expired or been cancelled. They include KnockOut and NaturGard 
(event E-176, Cry1Ab), Bt-Xtra (event DBT-418, Cry1Ac), and StarLink (event 
CBH-351, Cry9C). Although the EPA has allowed existing stocks of the E-176 
products to be used through the 2003 growing season, I do not expect to see 
much of this seed sold. Bt corn hybrids with E-176 events are efficacious 
against first generation corn borer, but decrease in efficacy as the plant 

The newest Bt corn hybrids on the block, or soon to be on the block, 
contain a Bt protein (Cry3Bb) that is toxic to corn rootworm. They have no 
effect on corn borers or any other caterpillars. This event is not 
currently registered for commercial use, but may be by the beginning of the 
2003 growing season. Depending on when it receives registration, growers 
may be able to take advantage of these hybrids or at least see them on a 
field level.

Of course, all of these Bt corn hybrids require certain resistance 
management practices. For more information on resistance management 
requirements for 2003, see NebFact NF00-425, Resistance Management for 
European Corn Borer and Bt Transgenic Corn: Refuge Design and Placement 
( For more information on a 
host of topics concerning Bt corn and biotechnology, visit the UNL 
AgBiosafety Webpage at

Tom Hunt
Extension entomologist
Haskell Ag Lab, Northeast REC

Characteristics of currently available Bt field corn
Bt Event and/or Cry-Protein          
Registrant Company        
Trade Name
Bt-11, Cry 1Ab
Syngenta Seeds, Inc.
Control of European corn borer, southwestern corn borer,and southern 
cornstalk borer. Suppression of corn earworm, fall armyworm and common 
stalk borer.
Mon 810, Cry1Ab
Monsanto Co.
Control of European corn borer, southwestern corn borer, and southern 
cornstalk borer. Suppression of corn earworm, fall armyworm and common 
Mycogen Seeds c/o Dow Agro-sciences LLC; Pioneer Hi-Bred International Inc./
Herculex I
Control of European corn borer, southwestern corn borer, fall armyworm, and 
black cutworm. Suppression of corn earworm.


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