In the last several years, every year I've grown around 4 plants of zucchini, usually of 2 or 3 different variety and I've always got bumper crops from them.
This year, instead of growing seeds, I bought in the garden centre a 4-cells of bush zucchini transplants. They are growing vigorously, flowering non-stop.... but no fruits are set. They produce lots of female flowers, but they are all yellowing and dying within few days. At first, I thought, maybe there are no pollinators? This could've been true at the beginning of the summer, but not now - insects are buzzing all over my flowers growing nearby. I tried to pollinate by hand - with the same result. Could this be because zucchinis I am growing are all the same variety and they cannot pollinate each other? Does a zucchini plant need another zucchini of different kind to successfully pollinate and produce zucchinis?