Cross Pollination of Apples
Cross pollination is critical for many fruit trees, particularly apples, pears, most plums, some apricots and older cherry varieties. Each of these types of fruit can only cross pollinate with other varieties of the same type of fruit. Even inside individual types of fruit there are some varieties that are either incompatible or have sterile pollen, so it is important to know the varieties that you are growing. The cross pollinating trees must both be blooming at the same time. If in past years your trees bloomed but produced few if any fruit, you need to do a variety and timing cross pollination evaluation of your trees.
To do your own apple cross pollination evaluation answer the following questions:
- Are the two apple tree you believe will cross pollinate different varieties?
- Are either of the two varieties a triploid? See below(1).
- Are the two trees planted less than 100 feet apart? The closer together the better!
- Are both trees in bloom at the same time? You need to record when each start blooming and when they reach petal fall.
- Do you have lots of bees work the blossoms?
(1) A few apple trees are triploids, they have three sets of chromosomes while all the other apples have 2 sets (diploid). The pollen of triploid apples is sterile and cannot pollinate other apple trees. Tripoid apples require a second apple tree to pollinate it, and the second apple tree requires a third apple tree to pollinate it. Triploid apples are popular as they tend to produce large high quality fruit and consistent crops year after year. The most common triploid apples grown in Coastal British Columbia are:
- Ashmead’s Kernel
- Belle de Boskoop
- Bramley’s Seedling
- Crispin / Mutsu
- Newtown Pippin
In theory, the apple varieties bloom over a 25 day time line and most fruiting varieties are in bloom for 5 days. A variety that blooms on day 5 should be able to cross pollinate another apple variety that blooms on day 8 but not one that blooms on day 15. To simplify things for customers of most nurseries in BC classify their apple trees as very early, early, mid, late and very late with the recommendation that if your tree is early, it can cross pollinate with another variety that is early, very early or mid. Either of these two methods can be confusing.
Observation provides the only accurate bloom timing information for your garden or orchard no matter what any “reputable” source or tree tag tells you. Universities, government agencies, fruit organizations and nurseries around the world are provide chronological bloom times of fruit trees for pollination planning. Not all the bloom times these sources provide for specific varieties are the same, resulting in a lot of confusion.