It was recently confirmed that European corn borer (ECB) has developed resistance to the Cry1F protein in Bt corn in Nova Scotia. More information on this issue can be found here:
Canadian Corn Pest Coalition Mitigation Recommendations for European Corn Borer Resistance to Bt Corn (Cry1F) in the Maritimes. Until we know whether the resistant ECB population has spread beyond the Maritimes, we recommend that all corn growers across Canada keep an eye out of any ECB damage showing up on any Bt corn hybrids this year and consider implementing the mitigation strategies in the document above to help reduce the spread of the resistance. This especially applies to those regions that have shorter growing seasons with limited selection of Bt hybrids to choose from.
In addition, extension entomologists recommend that growers should not purchase or plant single-trait Bt hybrids for ECB. Hybrids containing only Cry1F (Herculex 1 and Herculex XTRA) or Cry1Ab (some Agrisure hybrids) should be avoided as the risk of resistance increases if only one trait is being used to control ECB.
Growers should also avoid planting stacked hybrids that contain only two Bt traits, if one of those traits is Cry1F. The confirmation of resistance to Cry1F results in these two trait hybrids becoming a single trait hybrid in those regions where Cry1F resistant ECB populations exist. If still planting these hybrids, use caution and scout for unexpected damage. A structured refuge of 20% non-Bt corn within 400 metres of the Bt planting should accompany any hybrids that contain Cry1F and only one other Bt trait against ECB.
The following table indicates which traits control and do not control ECB. Growers should ensure that the hybrids they are planting includes at least two traits that control ECB.
If you have any questions about ECB or Bt resistance, please contact your corn company agronomist or any of the provincial specialists listed below:
Source : Field Crop News