Most of our tomatoes are turning out like this one. (Not sure what kind of variety of tomato this is by the way) Can anyone tell me why they all seem to come out half brown? It is not just the surface either; the insides on most of them are also quite rotten.
Its looking like it so where ever you grew those (land/compost) do give it three years as with potato blight before planting again in that same place. Crop rotation also is very important..potatoes one year, brassicas another year etc.
Are there black blotches on the leaves and stems of the plant as well as the fruit? Late Blight would not affect only the fruit, you would see black areas on the rest of the plant as well. In fact, usually the leaves and stems start turning black first. Late Blight spots are also usually seen on the top or sides of the fruit before the rot extends to the bottom.
Your pics look like Blossom End Rot to me. That isn't really a disease. It happens when the plant doesn't distribute calcium evenly throughout the fruit. The blossom end of the fruit is deprived, and dies and rots. Usually the plant sorts out the distribution on its own and fruits that develop later are fine. Some people like to add calcium to the soil or buy a spray that is supposed to help. I've tried that and never saw any difference between plants that were treated and those that weren't. BER doesn't always improve with some of my tomatoes that are growing in large pots at the edge of the driveway either, unless I move the pots. I think the heat reflected from the driveway onto the bottom of the fruit affects the tissues there even though the foliage is not injured. I can get BER on those fruits throughout the summer if the weather is hot and sunny for days on end. The tomatoes growing in the garden where heat does not get bounced up from a hot dry surface don't get BER.
Rotating your crops is a good idea if you have room. I wouldn't grow tomatoes where potatoes were growing the year before, though. They are related and can get the same diseases so you wouldn't gain much by following one with the other.