EFFECTIVE UTILIZATION OF TRANSGENIC TRAITS FOR INSECT CONTROL IN CORN

Summary

Seed companies have introduced new transgenic Bt traits in corn that is reported to control corn earworm. Field trials find that the traits prevent most ear damage by corn earworm. These new traits are marketed as Genuity VT Triple PROTM / Genuity VT Double PROTM and Agrisure Viptera® will be a useful tool for Georgia farmers to reduce losses in corn by corn earworm.

Situation

Corn is an important summer crops in Georgia. Acreage is expected to increase in 2013 due to high grain prices in response to demand for corn-based ethanol. Corn earworm, Helicoverpa zea, is a ubiquitous pest of corn in the southern U.S. It is common for nearly every ear in a corn field to be infested and damaged by this insect. Kernel damage by corn earworm also is associated with increased levels of damage by other insects such as sap beetles and by infections of various types of molds. Major seed companies have a new transgenic Bt trait marketed as VT Triple PRO or Genuity VT Double PRO that will be widely available in 2013 for control corn insect pests. Another different Bt trait will be marketed as Agrisure Viptera. These new traits are reported to provide control of corn earworm and prevent kernel damage, but the effectiveness of these traits has not been thoroughly evaluated in Georgia

Response

A series of trials were conducted in 2010 to 2012 to assess the efficacy of a new Bt trait (Cry2A) within Genuity VT Triple PRO and VT Double PRO and a new Bt trait (Vip3A) within Agrisure Viptera. Studies were conducted at CAES farms near Griffin, Plans and Tifton, GA. They compared corn hybrids with the new Bt traits, with an older single Bt trait, and without the new trait. Corn earworm infestation and kernel damage were measured and compared with similar hybrids without the new trait.

Impact

The both new Bt traits reduced infestation by corn earworm and prevented kernel damage in corn ears. While corn earworms still colonized Bt corn ears containing the Cry2A gene, nearly all earworms did not survive to reach a large size. Kernel damage also was almost eliminated although some infested ears still had some damaged kernels. Agrisure Viptera containing the Vip3A gene virtually eliminated corn earworm infestation and kernel damage in corn ears. The benefits of these new Bt traits were most evident in later plantings of corn when risk of insect infestation is greatest. This new Bt traits will provide a valuable tool for preventing ear infestation and kernel damage by corn earworm. The control will prevent yield loss but also will improve corn grain quality by avoiding secondary insect damage and fungal infection often associated with ear damage by corn earworm. In addition, Bt corn hybrids containing the new Bt traits which are combined (stacked) with an older corn borer trait also have a reduced resistance management refuge requirement which means farmers can protect a greater proportion of their corn crop from insect damage by using hybrids containing the new stacked Bt traits.

State Issue

Agricultural Profitability and Sustainability

Details

• Year: 2012
• Geographic Scope: National
• County: Spalding
• Program Areas:
  • Agriculture & Natural Resources