We have very vigorous growth of the leaves and the zucchini fruit. However, the zucchini stop growing at about three inches. They don't start rotting till much later, so I assume it's not ber. I don't think watering is an issue either as the rest of our garden it doing well. The only other thing that I might add is we appear to have minimal pollinators. Any suggestions as to what is happening would be greatly appreciated.