Across the corn belt depending on time of year | OK now you want to get into the "eye rolling" academics about refuges. Effectiveness of refuges is all about refuge size and relation to treated.
Soil Insecticide: We treat only in furrow (2") or a 7" band. Insecticide only moves down. In a 30" row, those 2" vs 28" means the refuge (untreated area) is 14x larger than the treated area or a 94% refuge. If we use a 7" bander (t-band), the refuge is 7" treated vs 23" untreated or the refuge is 3.3x larger than the treated area or a 77% refuge. Rootworms have never developed resistance to soil insecticides.
In fact, a 1970s study showed more rootworm beetles emerged from an insecticide treated acre (banded over the row) than an untreated acre. Why? because protecting the plant base with insecticide protected the roots away from the plant and the rootworms in the row didn't starve to death. Without an insecticide at the plant base, rootworm destroyed the roots at the base and the rootworms away from the plant starved.
BTW, the use of a soil insecticide only gives the farmer crop standability for harvest, it does little to kill or control rootworm.
The current seed mix refuge is a 5% refuge. See the difference in refuge size? 94% refuge vs 5% refuge. This is true of all corn with a pyramid of RW traits. Wonder why rootworm developed resistance to traits vs soil insecticide? Academics fought this tiny refuge predicting rapid resistance development. Guess who won? Farmers lost big time!
Single traits like Herculex RW or YieldGard-RW had a 20% refuge.
I will spare you the details about the argument of a separate refuge vs a seed mix.
Science was ignored, marketing won and the farmer lost! |
rootworm damage on CRW corn paid for by seed companies
