This is not the readers grapes but is what good berry set should look like Q. We had a problem with our thompson seedless grapes, the grapes are about the size of a ” bebe”, dried up and fell off. A. Unfortunately there is not much you can do about that. It was poor pollination. Climatic factors have a significant effect on fruit set. Fruit set is greatly reduced when temperatures fall below 65°F or exceed 100°F during set.             Rainfall or high humidity may reduce fruit set, hindering pollination. Rain can also interfere with the germination of pollen grains and inhibit fruit set. The berries appear to set and then fall off when they reach a small size. I hope this helps.