ChangingCottonLandscapeNeilForrester

The models above clearly indicate the importance of high dose (which equals high efficacy) in
managing resistance. This is why checking for efficacy in the range of various commercially
available Bt products is so critical. You should always choose the most efficacious products and
reject the poorer performing products which are a greater resistance risk requiring much larger
refuges. This is all the more important where structured refuges are not possible and where
natural refuges are all that are available. In these situations, the higher efficacy products will
require less natural refuge than the lower efficacy products for the same level of resistance
management. This is why the US Environmental Protection Agency (EPA) recently removed the
5% structured refuge requirement for Bollgard 2 in most of the US cotton belt but still maintained
the 5% refuge for Bollgard 1. They argued that the natural refuges were satisfactory for the
more efficacious Bollgard 2 product in most cases.
1
0
Poor expressing Bt
High Dose & Refuges
BG1 BG2
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