Depends a lot on your water. Depending on the pH many pesticides break down quickly once mixed.

Why do you need two fungicide, Immunox and Captan? What do you spray for?

i know you did not ask. I am just wonder if you overdo it. Captan can burn leaves if not careful.

don't know for sure but read somewhere that it is not good to keep spray mix around.

rphcfb14:

I use Captan and Rally in the spring mixed together. Immunox has the same active ingredient as Rally. Two reasons for doing this. First, Captan does not prevent Cedar apple rust but myclobutanil (active ingredient in Immunox and Rally) does. Second, Myclobutanil is much more rain fast than Captan as partially systemic. When we have a very wet spring like I had this year in SE WI, I use both Captan and myclobutanil together for normally good results against apple scab. Usually I use the Rally 2-3 times in spring mixed with Captan and switch to just Captan after petal fall. I guess the third reason to mix both fungicides together is because some strains of apple scab have developed resistance to myclobutanil (our state's University has reported this several times from issues involving commercial orchards in WI).

Spartan,

Glad you clarify it. Thanks. I use myclo but never Captan. I also do dormant copper. So far, so good.