Emmalea Ernest, Associate Scientist – Vegetable Crops; emmalea@udel.edu, Joanne Whalen, Extension IPM Specialist; jwhalen@udel.edu and Mark VanGessel, Extension Weed Specialist; mjv@udel.edu
In 2013 several new varieties of transgenic sweet corn with insect resistance from BT genes and herbicide tolerance became available to growers. The Attribute varieties from Syngenta, which have the Cry1Ab gene for corn earworm and European corn borer resistance have been available for more than a decade. Syngenta’s new Attribute II varieties have the Cry1Ab and Vip3A genes for corn earworm, European corn borer, fall armyworm and black cutworm resistance as well as Liberty herbicide resistance (see below). The new Performance Series varieties from Seminis, have the Cry1A.105 and Cry2AB genes for corn earworm, European corn borer and fall armyworm resistance as well as herbicide resistance to glyphosate/Roundup.
The authors of this article collaborated to evaluate various aspects of the Attribute, Attribute II and Performance series varieties in field trials in 2013.
Yield & Quality Evaluations
Table 1 lists the Attribute, Attribute II and Performance Series varieties that were evaluated for yield and quality characteristics in trials planted on April 17 and May 17. Supersweet and SE types were isolated from one another, resulting in four total trials. Commonly used non-transgenic varieties were also included in the trials for comparison. There were not significant differences in yield between the varieties tested except in the April 17-planted supersweet varieties. In that trial the BSS 0977, an Attribute variety, performed well, the two supersweet Performance Series varieties, Obsession II and SV 9010 SA, had average yields and the Attribute II variety, Protector, yielded poorly.
Table 1. Varieties Included in the 2013 BT Fresh Market Sweet Corn Variety Trials
|
Variety |
Transgenic Traits |
Color |
Isolation Group |
Seed Company |
| Temptation | none | Bicolor |
se |
Seminis (standard) |
| Temptation II | Performance | Bicolor |
se |
Seminis |
| BC 0805 | Attribute | Bicolor |
se |
Syngenta |
| BC 0822 | Attribute | Bicolor |
se |
Syngenta |
| Serendipity | none | Bicolor |
se |
Syngenta (standard) |
| Avalon | none | White |
se |
Syngenta (standard) |
| WH 0809 | Attribute | White |
se |
Syngenta |
| BSS 0982 | Attribute | Bicolor |
sh2 |
Syngenta |
| BSS 0977 | Attribute | Bicolor |
sh2 |
Syngenta |
| Obsession | none | Bicolor |
sh2 |
Seminis (standard) |
| EX08767143 | none | Bicolor |
sh2 |
Seminis (standard) |
| Obsession II | Performance | Bicolor |
sh2 |
Seminis |
| SV 9010 SA | Performance | Bicolor |
sh2 |
Seminis |
| WSS 0987 | Attribute | White |
sh2 |
Syngenta |
| Munition | none | White |
sh2 |
Syngenta (standard) |
| Protector | Attribute II | Yellow |
sh2 |
Syngenta |
| Vision | none | Yellow |
sh2 |
IFSI (standard) |
| Garrison | none | Yellow |
sh2 |
Syngenta (standard) |
The yield and quality characteristics of Temptation (non-transgenic) and Temptation II (Performance Series) were mostly equivalent. Temptation II had better tip cover in both trials and there were some statistically significant differences between the varieties’ ear diameter and number of rows. The appearance of the ears the two varieties is comparable. Similarly, Obsession and Obsession II were not significantly different from one another in yield and ear quality and appearance are quite similar between the varieties. Obsession II did have significantly shorter ears than Obsession in both trials. The “Obsessions” and “Temptations” all had good taste ratings in the trials. The other Performance Series variety that was evaluated, SV 9010 SA had yields that were equivalent to similar non-transgenic varieties and good taste ratings.
Protector, the only Attribute II variety that was evaluated, had lower yields than many of the standard varieties and had a below average taste rating. Because it is a yellow variety, it also does not have a great deal of potential for fresh market production in this area. Attribute varieties that yielded well in the trials and had good ear quality and tasted ratings include: BC 0822, BC 0805 and WSS 0987.
The full report on the quality evaluations is available online at: http://extension.udel.edu/ag/vegetable-fruit-resources/vegetable-small-fruits-program/variety-trial-results/
Insect Management Evaluations
Various spray schedules were evaluated on two transgenic varieties (Attribute II and Performance Series) planted on June 25 to identify the proper timing of insecticide applications for sap beetle and stink bug management. Current research indicates that these new transgenic events can provide 100% “worm” control. The same spray schedules were evaluated on two non-transgenic varieties for comparison. Since insect pressure for all species (corn earworm, fall armyworm, sap beetles and stink bugs) was unusually light, the data from 2013 cannot be used to make treatment decisions in 2014. Additional research will be conducted with the same varieties on two planting dates in 2014 to determine if the treatment schedules evaluated will be effective under normal and/or high insect pressure.
The full insect management report is available on line at: https://extension.udel.edu/ag/files/2013/12/Sweet-Corn-Bt-Variety-Trial-2013-final-Dec-18.pdf
Weed Control with Liberty 280
The Syngenta and Rogers hybrids with the Attribute trait received registration for application of Liberty 280 herbicide as a POST application. Liberty 280 provides a broad-spectrum herbicide with good crop safety. Liberty 280 rate is 20 fl oz/A (this is less than what is labeled for most other Liberty 280 uses). At this rate it is effective on small weeds (less than 3 inches) and requires a 50 day pre-harvest interval. It should be used following a soil-applied herbicide. One caveat is that soybeans can be planted immediately after sweet corn harvest, most vegetables require a 180 day interval between application and planting.