|The leaves are turning yellow and brown and the tomatoes are developing internal rotting.|
The leaves have a fungal disease. The fruit may have been attacked by fruit worms or suffered an internal decay from hot, stressful conditions. It is getting far into the summer for tomatoes to be thriving. If you feel there are still plenty of fruit to ripen and the plants have a good portion of their foliage it may be worth trying to spray the foliage with a fungicide containing maneb, mancozeb, benomyl or some copper based ingredient. The insects can be controlled by weekly sprays with a product containing Bacillus thuringiensis or B.t. for short.
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