Like many other plants, it may have started to produce buds and then they got caught by the frost - we had an unusually warm March followed by a freezing (comparatively) April.

I agree with Bamboo. My pear tree too a beating from the frost too. Next doors magnolia which is normally one of the garden highlights of the gardening year for me,because it hangs over my garden, had its beautiful petals ruined by the cold and ice.

Yes one of my Red Love apple trees has got a profusion of red blossoms and the other has none. They are in different parts of the garden and I can only assume the frost got at one of them.