This is my first attempt to raise tomatoes. I am growing them in 20 gallon smartpots filled with moisture controlled potting mix. Daytime temps have been in the mid-80's here in Central VA, so I have been watering deeply once a day.

During the course of a single night, one vigorously growing tomato plant started developing brown leaf edges and the smartpot became coated in a white powdery substance.

Is this a disease, pest, soil or watering issue? Thank you in advance for any assistance or insights!