Matthias Schmid, head of the Experimental Station for Fruit Growing in Wädenswil, explains what’s happening and answers frequently asked questions.
Why are the trees blooming now?
It’s not unusual for trees to bloom a second time; we see it occasionally, depending on the variety. In the current mild temperatures, the tree is not yet storing nutrients and hasn’t finished growing. When a tree has enough energy, it produces flowers.
Does repeat blooming harm the trees?
This autumn blooming doesn’t affect next year’s yield in any relevant way: a few flowers always open in late summer, but plenty are left for the coming spring. Even professional fruit growers see this from time to time on one-year-old shoots. These are then cut off in winter together with any small fruits that have grown on them. As there are so few of them, we can assume this doesn’t harm the trees.
Will this mean fewer apples next year?
No, the effects aren’t significant. What matters are the flower buds on older shoots. Certain inhibitors that prevent sprouting are produced in the buds. This sprouting inhibition breaks down only if the buds are affected by cold for a given period of time. Then it’s only the cold winter temperatures that prevent the buds from swelling and sprouting.
Does the autumn blooming affect the “normal” blooming next spring?
No, permanent crops are more likely to be exposed to major events that throw a tree out of balance, such as a hailstorm. In this case a tree takes one to two years to recover, depending on the severity of the hail.
Is it important in any other way?
It’s useful for insects because it provides a source of nectar. The tiny fruits can also serve as food for animals.
