Q.White Speckle Disease
Hi, I dealt with this problem midway into summer last year with a new garden I planted. It dominated my Zinnias and dahlias and then the 4’oclocks got hit with it. I pick off the infected leaves but I’m left with nearly nothing afterwards:( I spray neem oil at least 1x per week (& hit underside of leaves). My plants are spaced as they should be with room to breathe and right now no plant touches another in the garden. I water from the bottom close to ground. I used a copper fungicide last year as well but it still kept coming. What is this and how do I get rid of? It spreads like crazy. Lower leaves is where it seems to start or be the worst.

Certified GKH Gardening Expert
I believe that is spider mite damage, rather than fungal. Since the Neem oil isn't working you might try a miticide.
https://www.gardeningknowhow.com/plant-problems/pests/insects/spider-mite-treatment.htm