Production Blog

There's a life hack to keep the insect and herbicide traits within corn hybrids straight. It's called The Handy Bt Trait Table.

The free, two-page online document lists the types of Bt present in all commercialized corn in the United States. It presents the trade names for traits, Bt event, protein(s) expressed, targeted insects and herbicide traits. A new version of the chart was updated on Jan. 8, 2024. Find it here: https://www.texasinsects.org/….

Chris DiFonzo, a Michigan State University entomologist, is the primary gatekeeper of the table. She calls the table "a living document." Each year she sorts through ever growing list of trait stacks to update the chart to help farmers determine what lies within the seed they are buying.

That's getting more complicated each year as more traits stack together and cross company lines. The table helps farmers plow through seed guides, sales materials, and bag tags to determine what is different or comparable. It lists refuge requirements for northern states or whether the refuge is blended within the purchase and at what percentage. Southern growers may have additional refuge requirements because of the proximity of cotton acreage.

To supplement the information, DiFonzo has also put together a checklist of Bt events by stack, a table of Bt events and list of EPA registration numbers. For all those links and a video describing how to use The Handy Bt Trait Table go to: https://www.texasinsects.org/….

The publication also highlights insect and Bt combinations with documented field failures, confirmed resistance or cross-resistance. The statements are based on published lab assays and/or field research to alert farmers and consultants to potential management problems, help with seed selection and encourage field scouting. A list of citations for those failures is also available.

DiFonzo cautioned that it's important to remember the table is a national publication, and resistance may be widespread, regional, or limited to a few fields. Local seed representatives and Extension personnel can help sort out what resistance pressures are present in your area.

Sweet corn does not have as many traits available, but a list is kept by Michigan State University vegetable crops educator Ben Phillips. Find it here: https://www.texasinsects.org/….

Another thing to watch this year is the scientific community has been making some changes in the names of bacteria-derived pesticidal proteins. For example Cry34/35Ab1, commonly known as Herculex RW and found in many common trait stacks, is now Gpp 34Sb1/Tpp 35Ab1. DiFonzo continues to list it as previously known until more literature gets changed. Here's a scientific paper on those changes:

https://www.sciencedirect.com/….

Pamela Smith can be reached at pamela.smith@dtn.com

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