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Walnuts are mainly found in gardens. Often the walnut tree of the previous owner is still on the property. The magnificent trees, which can grow up to 30 meters high, provide ideal shade in summer. In autumn they delight us with their delicious nuts, which refine many dishes, if it weren't for the late frosts that freeze the leaves and flowers of the tree.
real walnut
Worth knowing about the real walnut
The real walnut, botanically Juglans regia, belongs to the walnut family (Juglandaceae). It is better known in Germany under the name walnut tree or simply as walnut. In Austria it is also called Welschnuss, or in Switzerland Baumnuss. The walnut tree is a good 150 years old and has been documented since the Tertiary period. In principle, the walnut can withstand temperatures down to minus 20 degrees Celsius, but late frosts cause considerable problems for the leaves and flowers.
late frost
Walnut trees are very sensitive to late frosts. The most dangerous time for the walnut is between April and June. During this time, the walnut tree develops leaves and flowers. Even temperatures just below zero lead to frost damage during this time. Luckily, you can tell quickly and easily whether the walnut tree has suffered forest damage.
- the leaves turn black overnight
- the flowers have assumed a brown to black color
Tip: "Late frosts" are also dangerous when spring comes earlier. If the temperatures rise early, the nut tree will sprout earlier. Time-related night frost can then lead to damage.
On leaves
If the young leaves have frozen, there is not much you can do about it. The damage has been done and one can only hope that the tree will sprout again.
- watching tree
- New growth should start after a few weeks
- Fertilizer gives the tree extra strength
- make sure there is enough moisture
It is important that the tree sprout leaves after the late frost. He needs her to survive. If it loses its leaves, it dies and has to be dug up.
Tip: Do not cut off frozen leaves. The resulting open wounds only cost the tree additional strength. In this case you can leave the disposal to the wind.
Of flowers
If the late frost has caught the blossoms, this can affect or even destroy the harvest. Walnut trees are monoecious plants. So there are male and female flowers on a tree. The male flowers usually appear four weeks before the female ones. Pollination is done by the wind. Therefore, a late frost on the flowers can lead to a crop failure, especially if the male flowers are frozen. Because if there is no other walnut tree nearby, pollination cannot take place.
Tip: Contradictory as it sounds, the loss of flowering can also have positive effects on the walnut. Since the tree does not produce any fruit this year, increased growth may occur.
prevention
preventive measures
Large walnut trees cannot be protected from late frosts because they are simply too large. On the other hand, smaller trees can be protected from the cold night with a fleece. In this way, the damage can at least be kept within limits.
Tip: The risk factor "late frost" can also be reduced if you plant a late-blooming variety.
Refined walnut tree
Late frost on grafted walnut trees
In the case of late frosts, the main shoot of a young heister can freeze. A rescue is possible if the young tree has strong roots and sufficient reserves for renewed growth.
- after the frost night, cut off all the frozen leaves
- Leaf stalks remain
- New shoots will sprout from Beiaugen after a few days
- Connect the lead drive
- Carefully cut off frost-damaged shoots after a while
Tip: If crown branches have already formed after four to five years, the grafted walnut can be treated like an adult plant.