Is this a kind of plague?

It's White Powdery Mildew. It's a minor annoyance that can be easily fixed, your gonna want to take some paper towels and water and remove the mildew from the leaves first, you're also going to want to make sure you have proper airflow and ventilation, then take and put 1 teaspoon of 35% Hydrogen Peroxide into a gallon of water, after you mix that up, take a spray with the mixture and spray the all the leaves, do this right before lights out.