These spots started showing up on the leaves of my seedlings a day ago. I can’t tell if it’s a type of nute burn or if it is mildew. My humidity levels were extremely high but I lowered them and sprayed water with hydrogen peroxide and baking soda on the leaves today just in case if it is. Any thoughts?
Hmmm... A little hard for me to tell by looking at the picture. I definitely don't see nute burn. How is the air circulation in your grow space? I like 70%+ humidity for seedlings but I always make sure a fan is in the grow space moving the air around. Stagnant air greatly increases the chances of powdery mildew occurring.
My humidity has been at about 80-95 because of the dome. I took rockwool cubes and proped it open to lower humidity. I have no air circulation in my grow space at the moment but I will when they are transplanted into my 4x4 tent. Currently they are just in a seedling propagation tray coming up on week 2 after germination. The spots on the leaves kind of look like a brownish tan color to the naked eye and some spots are a little bit lighter colored.