Apple tree only flowering on one side

Question

I have a peculiar problem with an apple tree in my backyard. As you might be able to tell from the picture below, it's only flowering on one side. That's not too weird if it weren't for the fact that last year it did the same, but on the exact opposite side. And all the years before that it just bloomed normally. The flowers aren't also just distributed on specific branches. Both times the flowers seem to choose branches at random as long it's on the side of the tree that blooms. If that branch goes to the other side it simply doesn't bear any flowers over there.

My father, who planted the tree, says it's around 20 years old and that it's of the 'golden' species. We didn't do anything special to the tree nor did we do any building work, soil management or other alteration to the surroundings in the last two years.

Would anyone be able to shed light on this? While I have searched, but I haven't found any information that can clarify this so far.

Answer 1

This could be a strange version of "biennial bearing" which is a well known fruit tree problem.

It can be started by something happening which reduces one year's crop. This results in over-production of flowers the following year which over-stresses the tree, resulting in no crop the following year, and the two-year cycle continues.

Maybe one half of the tree was damaged by bad weather somehow and the two "halves" are now on opposite two-year cycles. From the picture, you almost have two independent trees joined at the trunk, not a single trunk with several side branches.

If that is the case, one cure for it is to remove about half the flower buds to reduce the crop, and try to get the tree back into producing every year. Try to make sure the tree has adequate water and nutrients to support producing a crop as well.

Note, thinning the fruit after it has "set" is a much less effective cure than removing the flower buds before pollination, because the pollination process produces hormones which affect the tree's behaviour for the following year.