I have used it very successfully to prevent growth of grasses while planting sunflowers. I used it as both a preplant (sprayed and then incorporated) as well as pre-emergent, applied directly after planting. Yes it does have a residual, and that is the purpose and how it does so well.
The grass control in my sunflower patch was so good and so complete, that I didn't even spray Clethodim this year as I thought it would be wasteful; there just weren't any grasses to kill. Still had the usual broadleaf weeds, but I added Spartan pre-emergent and had fewer.
So if grasses had been a big problem in the past, Dual might be a good pre-emergent to try. Would love to hear other's input on the use for brassicas.
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