a feature of crab apples that’s often overlooked is their role in pollinating eating and cooking apples.
To set a good crop, most eaters and cookers need to be pollinated with pollen from a different variety that flowers at the same time. Crab apples, meanwhile, not only need no pollinator themselves, but also flower for much longer than culinary apples and can produce up to 10 times as much pollen. So your crab apple tree (or that of your neighbour) will pollinate most of your culinary apples. In fact, some commercial fruit growers plant a crab apple at the end of each row of trees.
You may only need one crab to pollinate all your culinary apples. Even if you have a range of eaters and cookers, an early flowering crab such as ‘Laura’ or ‘Red Sentinel’, plus a late-flowering one such as ‘Comtesse de Paris’ or ‘Wedding Bouquet’, should do the trick.
Crab apples produce more pollen than culinary apples