Moving into July and early August, there is the potential to apply herbicides in the same tank with fungicides. Here are some general findings from previous research. Note that Clethodim and 2,4-DB are the herbicides we are most likely to apply going forward.

In our research, we have not observed issues when 2,4-DB is applied with fungicides. Of course, we have not looked at all fungicides and 2,4-DB, but generally I would say you can apply these pesticides together.

Chlorothalonil products and Headline can reduce annual grass control with clethodim products. We don’t use Headline alone now, but Prioxor is used. Historically, grass control is 30-40% lower with these mixtures.

We have not observed a decrease in grass control when clethodim is mixed with Provost Silver or Folicur. My assumption is that generic tebuconazole will respond the same as Folicur.

Grass control with clethodim plus Miravis and Elatus was not lower when these pesticides were mixed.

We have not looked at newer products like Revytek and Lucento with herbicides.

I always recommend the higher rate of clethodim when applied in tank mixtures.

Note that across the years I have always added 1 quart of 80/20 nonionic surfactant with 2,4-DB. Many times growers do not include surfactant. I do not think response to mixtures of 2,4-DB and fungicides will change with or without surfactant.

I have always included crop oil concentrate with clethodim alone or when mixed with fungicides. Keep in mind that some fungicides are used to suppress stem rot and/or Sclerotinia blight. Fungicide needs to reach the base of the plant for the pathogens causing these diseases. We have not looked into this in great detail, but there is some concern that crop oil would minimize movement to the base of the plant.

As always, check with the product label about issues with tank mixtures.