Outside of the corn borer-infested area, this trait was tested at one location. At that location, the hybrid with the Bt trait yielded 6 bushels per acre more than its non-Bt isoline. This trait slightly reduced caterpillar feeding within the ear. The amount of caterpillar damage was more than was expected for this Bt trait.

Genuity VT Triple Pro (Cry1A.105, Cry2Ab2 for above ground caterpillar pests and Cry 3Bb1 for below ground rootworm pests). Within the corn borer-infested area, hybrids with the Genuity VT Triple Pro trait yielded a median 6.5 bushels per acre more than their non-Bt isolines. The range of the differences was from -11 to 14 bushels per acre.

Outside of the corn borer-infested area, hybrids with the Genuity VT Triple Pro trait yielded a median 7.5 bushels per acre more than their non-Bt isolines. The range of the differences was from -7 to 18 bushels per acre. This trait greatly reduced caterpillar feeding within the ear. This is consistent with predicted effectiveness of this Bt trait against corn earworm.

Genuity SmartStax (Cry1A.105, Cry2Ab2, and Cry1F for above-ground caterpillar pests and Cry 3Bb1 and Cry34Ab1/Cry35Ab1 for below-ground rootworm pests). Within the corn borer-infested area, the hybrid with the Genuity SmartStax trait yielded a median 2 bushels per acre more than its non-Bt isoline. The range of the differences was from -9 to 13 bushels per acre.

Outside of the corn borer-infested area, the hybrid with the Genuity SmartStax trait yielded a median 0 bushels per acre more than their non-Bt isolines. The range of the differences was from -10 to 7 bushels per acre. This trait greatly reduced caterpillar feeding within the ear. This is consistent with predicted effectiveness of this trait against corn earworm.

Agrisure Viptera 3111 (Vip3Aa20 and Cry1Ab for above-ground caterpillar pests and mCry3A for below-ground rootworm pests). Hybrids with the Agrisure Viptera trait yielded a median of 13 bushels per acre more than their corresponding isolines with the Agrisure 3000GT trait. The range of the differences was from -5 to 23 bushels per acre.

A non-Bt isoline was not available for these two hybrid families.

Both Agrisure 300GT and Agrisure 3111 are highly effective against corn borers, so it was not necessary to separate the yield response into areas with and without corn borers.

This trait produced the greatest reduction in caterpillar feeding within the ear of all the traits tested. This is consistent with predicted effectiveness of this trait against corn earworm.

The median difference for each Bt corn trait indicated that more often than not, hybrids with a Bt corn train yielded more than hybrids without a Bt corn trait, says Flanders.

“Yield differences are most likely attributable to corn borer, corn earworm and fall armyworm infestation, but it is possible that protection against other caterpillar pests also contributed to the yield differences,” she says.

phollis@farmpress.com