Hi Bill,
Yes there is but as with many things in QU, it's not like PS  
It's called Selective Color and you can learn about it from this video:
https://www.youtube.com/embed/8voqBtCf6aI

It is in fact a very powerful, precise and versatile tool but no sliders, just numbers.
There are some pre-sets for creating monochrome using the folder icon in the SEL COL  tab of the image editor.
There is also the Smart Color icon for boosting colours without blowing them.

The main Help explains how the numbers work in the SEL COL table. Click into one of the boxes and hit F1 to get there quickly.
Terry
PS. I forgot to say the ordinary saturation adjustment in the editor does have Y Mg Cy in addition to RGB. See screen shot attached.

Thanks to both of you. That's an interesting feature of QU which I hadn't explored. It seems to be more flexible and powerful than the sliders in PS CC. I'm not sure I completely understand the conversion of the red flower to a yellow flower, but I don't need such an extreme color correction - just a touch more blue, a touch less yellow, but that has to be over the entire print. I'll work on it.