You know how it is in your neighborhood. You want to be the first one on your block to pick the first tomato. Tomatoes are the most popular vegetable grown in America. We're just upon the beginning of the harvest. Early varieties won't be as large as later varieties. Stupice and Early Girl are examples of early tomatoes.
If you go to pick a tomato and the bottoms are all black and rotted, then the plant needs calcium. This is called blossom end rot. The lack of calcium can be a result of low nitrogen. When a plant suffers from low nitrogen it is unable to absorb calcium. So sometimes fertilizing with manure tea or a side dressing of compost can help. If this doesn't help you can also apply calcium directly to the soil. It usually comes in granular form and can be found at your local hardware store. They do make a foliar spray, but I'm not sure how well that works.
If your plants are starting to brown from the bottom, it could be from blight or leaf spot. There are certain varieties out that are less susceptible to these deadly diseases. You can also do periodic monthly sprayings of copper sulfate to help prevent the disease. Mulching also helps stop the spread of both diseases since they are soil born. Once it starts it's good to take off the dead foliage. Do not compost, nor burn. It could infect other plants. Other things that could happen because of blight or leaf spot is sun scold on the fruit. You could still get tomatoes off an infected plant. It's just your production will be lower once they set in. To help prevent sun scold pick the fruit when young. Store in a dark dry place and they will ripen.
Another predator to the tomato is the tomato hornworm. These worms, I think, are really cool looking even though they will eat holes in my fruit. As a kid, I remember Dad burning tomatoes and seeing a horn worm on one of the tomatoes and I ran in to save it from the fire. My Dad yelled at me but the worm was saved. I wouldn't let Dad kill it. I kept it.
One of the natural predators to these worms is the parasite wasp. If you've ever picked a worm off the plant that had yellow things attached to it that look like eggs, these are the eggs the wasp laid on the worm. While in the larvae stage they live off the worm. That's a pretty bad way to go for a worm.
Another natural method to control these worms is Diatomaceous Earth. When the worm crawls across they get cut, another cruel way to take out a hornworm.
Despite my love for the hornworm, I love picking healthy tomatoes even better. Nobody loves holy tomatoes, and we aren't talking about the ones that are blessed. Nothing gives me greater pleasure than picking a tomato.
The heirloom varieties might not be the prettiest looking but they make up for it in taste. The market has really changed. It isn't about appearance anymore. It's about taste and flavor now. While my Dad's favorite tomato was 'Big Boy' my favorite is 'Cherokee Purple', second runner up, 'Mountain Fresh'. They are two of the best tasting tomatoes around. One's an heirloom and the other a hybrid.
If you walk through your garden and see that your tomatoes are really ripe yet and it's been very dry and then you hear that the weatherman's calling for rain, you might want to pick your tomatoes. A big influx of water after a dry spell will cause tomatoes to crack and split.
These are a few tips for totally tasty tomatoes.
P.S. If you're looking for a good source of info, the University of Illinois has a book called, 'Vegetable Gardening in Illinois'. Books on First can get it for you.