The odds greatly favor growing conditions, not disease. Disease is the last option to be explored. So we need to know where you are located - I assume way south since you planted out so early - and if these plants are in the ground or in containers. We need to know what mix is in the containers, what fertilizer you use, how often you water, how big the containers are, any pest problems, etc. In other words, much more information please.

Dave

Sorry, I should've included more information. So here it is: I'm in southern California, zone 10. This plant was planted in a 7 gallon container, and is put out on our rooftop deck where it gets full sun about 6 hrs/day, sometimes even more. I planted it in a container with Ocean Frost potting soil, and I applied Dr. Earth tom, veg, herb fertilizer only once when I planted it in Feb of this year. I water every other day, or when the soil looks dry, I water thoroughly as I read that's the best way to water these tomato plants. I water in the morning before going to work, and I also adjust for rain (which hasn't happened that often, but it has rained pretty hard for a day or so, within the past couple weeks).

Hope that helps! :) Thanks!

Cenesia