Allen Wilson is a Vancouver gardening specialist. Email Allen Wilson at firstname.lastname@example.org.
My apple trees had more blossoms this spring than I have ever seen. I understand that when apple trees have a heavy crop one year, they tend to be very light the next year. Is there anything I can do to reduce this year’s crop? What is the best way to keep worms out of the apples?
The biannual bearing of apples is quite common. Trees store food for next year’s crop. When they have a year with a very heavy crop, there are limited food reserves for the next year, resulting in a smaller crop.
Apple trees produce flowers and fruit in clusters of five. If all five are pollinated and set, fruit will be very small. Orchardists try to reduce fruit to one per cluster. In fact, they often spray to prevent pollination of the rest of the flowers after one has set.
You can thin heavily to reduce your apple crop. You first need to wait a couple of weeks because the tree will naturally drop some fruits. Blossoms that were not pollinated will not develop into fruit. With a very heavy set, you will need to leave only one fruit per cluster of five. In fact, where clusters are less than 3 or 4 inches apart, you may want to remove some clusters entirely. Always leave the largest apple in the cluster. If you leave two apples in a cluster you will get medium-size apples, three or more and the apples will be small.
Now is also the time to prevent wormy apples. The small, dirty-white codling moth lays eggs on apples that hatch into larvae (worms) and eat into the apple. Moths are most likely to be seen at dusk.