MSU Extension:
For many gardeners, the end of August and beginning of September are the big times for harvesting ripe tomatoes from their home gardens. As is the usual case, those same excited gardeners have planted too many plants and a great number of tomatoes are being picked almost daily. What many of these gardeners are finding is these ripe tomatoes are rotting rapidly. When the gardeners looked at their plants, the leaves and stems looked good, the fruit was good, but what happened to the lovely tomatoes?
The answer is anthracnose (Colletotrichum coccodes). This is fungus that causes fruit to rot and can also be responsible for a high mold count in canned tomatoes.