Clay Putnam, CGCS said: Jeremy,
I can give you my experience with three of the products you mentioned when used to control pythium.
I always rotated products when applying fungicides for pythium on a preventative basis. I did not want to experience resistance so I rotated products. Particularly with pythium being the animal that it is.
Subdue - a good preventative product with relatively low use rates. Longer residual. Not good for curative sprays. Can get the product in granular form if needed.
Banol - a good preventative and curative product. Longer residual. Good to keep on the shelf when emergency curative apps are required.
Terrazole - a good curative product and rotated preventative product. Shorter residual. Good to keep on the shelf when emergency curative apps are required.
I would agree with this, except I've found that Subdue is better for Pythium blight whereas Banol is better for Pythium root-rot.
Although we include a phosphite in our weekly sprays, I have found that nothing controls Phythium root-rot quite like Banol.