You should also consider closely related ornamental plants as good pollinizers. For example, crab apples can pollinate apples, and the ornamental Bradford pear can pollinate pears. For fruits that require cross-pollination, refer to the individual chapters covering those fruits.
Apple: Cross-pollination is always needed to produce an adequate fruit crop.
Apricot: All varieties are self-fertile, but cross-pollination is helpful.
Blackberry: Most are self-fertile, but a few require crosspollination.
Blueberry: Fruit set and crop size are improved by crosspollination.
Cherry, Sweet: Most older varieties are self-unfruitful. Recently, however, a number of new self-fertile varieties have been developed.
Cherry, Red Tart: The commercial varieties are self-fertile.
Gooseberry: Most varieties are self-fertile.
Grape: A variety of flower types (perfect, male only, and female only) exist. To assure good crops, consult an extension specialist to determine the proper variety mix to assure fruit set.
Peach: All commercial varieties, except J. H. Hale, are self-fertile.
Pear: Some varieties are partially self-fertile, but planting at least two varieties is best to ensure cross-pollination.
Plum: A wide diversity occurs in the plums; about half of the varieties are self-fertile and half are not. To be on the safe side, provide pollinizers.
Quince: All varieties are self-fertile.
Raspberry, Black: Most are self-fertile.
Raspberry, Purple: Self-fertile.
Raspberry, Red: Most are self-fertile, but crop size is improved by cross-pollination.
Strawberry: Some known varieties produce imperfect flowers, but most are self-fertile.