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This looks like sunscald to me. I don't see any of the yellowing and black/brown spots as you see with blight.
Put some shade cloth around it for the next several days or until the weather changes to more cloudy days that will help shield the leaves. The weather is going to be very warm to warm next week.
Environmental factors which promote this type of injury are intense sunlight and low humidity following periods of high humidity, warm temperatures and cloudy weather. There also appears to be some association with heavy applications of fertilizers which tend to promote spurts of rapid growth.
The only means of reducing injury is to use well drained soils (which looks like you have from your picture) and adequate but not excessive fertility. Your tomatoes should be fine.
However, I do not see a lot of tomatoes. Have you harvested them already? You can get the green ones to ripen by withholding water.
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