Compatibility issues. Help me to understand Captan, oil and copper octanoate

A consult from the forum please…

I have found that copper octanoate (specifically the Bonide version) is at best mildly soluble in water. It in fact stained the inside of my backpack sprayer blue. It took quite a few washes to dissolve the blue stain material. This is not surprising as it is a copper salt of a longish chain carboxylic acid.

The label indicates that the copper octanoate can be used during the growing season as it has considerably lower phytotoxicity.

Many posts indicate Captan is not compatible with oil. This leads to the questions I would like to ask the forum:

  1. Why does one not use captan with oil? Is it an emulsifiability issue? or something else?

  2. Is Captan compatible with copper octanoate? Should copper octanoate be thought of as a class of oil for compatibility purposes?

Much obliged.

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Horticultural oils vary greatly in chemical components.

Also, there are two forms of Captan:

Liquid
ld2LS004.pdf (138.0 KB)

Water-dispersible granule
ldAFJ003.pdf (118.0 KB)

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Thanks. Even the liquid label for liquid captan instructs to neither combine with oil nor closely follow oil sprays.

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