ASK A MASTER GARDENER: This year’s birch trees may hinge on last year’s weather
Q: I have a clump of three paper birch trees. This spring, only two branches got leaves, but they never developed. Is there any chance they will come back? Also, I have a problem with my Minnesota State Fair apple tree. In 2012, we had the best crop ever (40 to 50 dozen!). Last year, we only got two dozen, and this spring only had about 12-15 blossoms. Is it resting after a “bumper” crop in 2012 or is it dying?
A: Spring leaves are formed the previous fall. Low temperatures can kill buds outright. Sometimes, they survive and the tree has enough stored energy to get them started, but the tissue that supplies the leaves with water has been damaged. When the buds or leaves need water, they have no way of getting it because the vascular highway has been wiped out and so they die.
The viability of your birches depends on how far down the damage goes. If it were earlier in the season, I would recommend you scrape a little bark off near the base and look for green right below the surface of the bark. If you found it, there is still some life in the tree. However, if the birches don’t have any new growth by now, they are dead.
The State Fair apple is what is called a biennial bloomer, which is common in apples. One year it gets a heavy crop of apples, the next year it blooms very light. That is again because it forms the next year’s buds in the fall.
In autumn 2012, the bumper crop exhausted your tree and it had little energy left to form buds, hence the sparse 2013 crop. After a light year, it should have been ready to go again and probably was set to give you another good harvest, but the cold damaged the buds. As long as the tree looks healthy, everything is fine and, with luck, it will have a great 2015.