I have lots of zinnia's in all my beds....they are all getting a whiteish spots on them..the spots will not rub off...and then the leaves curl and turn brown....I realize that we have had to much mosture this year...but I really don't know what this is or how to treat it....

Sounds like powdery mildew, the plants may be stressed because of the intense summer heat and humid nights. I don't know your location so I can't be certain about the humidity part. I know zinnias don't like high heat and humidity. As for the powdery mildew, you can make your own baking soda fungicide, or buy potassium bicarbonate fungicide at the store.

Howard's baking soda fungicide recipe

Moisture is indeed the key........another way to help reduce this is to water any plant susceptible to Powdery Mildew is to water from the bottom being very careful to keep water off of foilage.