By Larry Hodgson
Question: To add an extra room to our house, we had to cut down a 15-year-old apple tree. That leaves our other apple tree, a different variety but of the same age, and very productive so far, without a companion tree to ensure pollination*. We don’t have enough room to plant another apple tree, but both of our neighbors have crabapples in their yards. Can a crabapple tree pollinate apple blossoms? If so, will this cross-pollination affect fruit quality? And if so, what is the maximum distance between apple trees to ensure bee visits? In our case, one of the trees is about 25 ft (7 m) away, the other, more like 60 ft (20 m).
*Apple trees are self-sterile: it takes pollen from another variety to stimulate fruit production.
Answer: Botanically, there is no difference between an apple tree and a crabapple tree. Both are selections of Malus domestica, the apple tree having large edible fruits and the crabapple having small fruits (although still edible) and mostly cultivated for its beautiful blooms. For that reason, the two can pollinate each other.
And pollen from a crabapple will in no way affect the fruit quality of an apple tree. If your apple tree is a ‘Gala’ or a ‘Liberty’, it will keep on producing the same ‘Gala’ or ‘Liberty’ fruits it always did. The seed inside will have mixed genes, but the fruit growing around it is essentially the swollen ovary of the mother plant and so will produce fruits typical of the mother plant.
In addition, it is usually estimated that to ensure good bee pollination, apple trees should not be more than 100 ft (30 m) apart and the distances in your case are well within that range.
So, no, you won’t have to squeeze another apple tree into your yard. Bees will be sure to carry pollen from the crabapples to your apple tree, ensuring good fruit production.
This is not the only case where human beings have given more than one name to what botanists consider to be the same species. For example, the beet (beetroot) and Swiss chard are both Beta vulgaris and can therefore interbreed, while cabbage, cauliflower, kale, ornamental cabbage, broccoli, Brussels sprout, kohlrabi and many other “cabbages” are botanically Brassica oleracea and can also cross and produce viable seeds.