Suitable crab apple varieties
Although a crab apple flowers at the correct time and the pollen is shown to be compatible from hand pollination tests, this does not necessarily mean that it is the best one. Research conducted in the United States and at Orange in NSW has shown that bees, when out foraging apple blossoms, tend to stay with the same colour flower and fly past a different colour, especially if the blossom colours are very different, such as deep red or white with a tinge of pink. This could negate cross-pollination. Although there are reports of using a red crab apple variety in New Zealand, pollination there is carried out by both honey bees and bumble bees. We have no bumble bees in Australia, and we rely on honey bees for most pollination.
Most crab apples have quite a long flowering period due to spur flowers opening first, followed by one-year-wood flowers. Delicious varieties tend to flower only on spurs, but many other varieties flower on spurs and one-year wood. Spur flowers when set tend to produce larger fruits of more even good quality, rather than a mixture of fruit on spur and one-year-old wood, for storage as well as for grading.
Here are the best varieties of crab apple pollinators in terms of timing of flowering, from a wide range of commonly available species.