A grower asked if the following could be applied together.

Provosol, Tebuconazole, Clethodim, and Peg Power

Not on the list was crop oil concentrate.  Adjuvant is needed for the grass herbicide clethodim (the active ingredient in numerous brand names) to be effective. The grower asked if this could be left out. My answer was no. Weeds that are above the canopy now are large, and herbicides need to have everything stacked in their favor to perform. Adjuvant is critical for Clethodim to work well.

My concern with the mixture, when crop oil is included, is how it might affect Provosol. Primary from an injury standpoint. But also, crop oil concentrate could hold more fungicide in the top of the canopy and this could affect southern stem rot control at the base of the plant. Also, some fungicides reduce grass control by Clethodim. We have not looked at Provosol.

My recommendation was Provosol plus Tebuconazole plus Peg Power as one spray. The other spray would be Clethodim plus crop oil concentrate. While I would generally spray Clethodim first and then the fungicide treatment just a few days later, this time of year, I would not be late on a fungicide spray with our weather patterns.

I detected disappointment in the growers voice. I really do get the logistical challenges of sequential sprays.