I have tomatoes growing under fluorescent lights indoors, and a month ago a few of them began showing symptoms of necrotic looking spots on leaves followed by bleaching. It has now spread to about 1/4 of the population, with infected plants grouped together. It's an F3 population (approx 200) of Micro Tom x Black Cherry. I'm growing a Micro Tom next to them that is also severely infected. I have been growing plants, including tomatoes (and the entire F2 generation to maturity) under the same conditions for several years with no problems, and the current symptoms are not uniform across the population, so I'm fairly certain it's not physiological.