Thank you for your question, Linda.  Since there are six common zinnia diseases in this region, we cannot recommend a treatment without first identifying the pest.   https://pnwhandbooks.org/plantdisease/host-and-disease-descriptions?title=zinnia

Some diseases are fungal; others are bacterial.  Treatment differs for each.  Could you please send a clear, closeup photo of the tops and undersides of the leaves, as well as a photo of an entire plant?  Thank you for more information!

Here are some photos you suggested I send to you. 

Thank you for the photos.  Since the symptoms are not consistent with diseases, I asked OSU's top plant pathologist to look at them.  His opinion is that these appear to be suffering from sunburn and/or insufficient water.  Are they in direct sun?  Have you been monitoring soil moisture and watering frequently?  Remove the leaves, but don't treat with anything.  Good luck!