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Mouse’s ear and frost stage – what does the science say?

The wave of frost and frost that passed through Europe this and last week took a heavy toll. Polish fruit growers are also afraid of frost. What temperatures are needed to lose apple trees?

The percentage of losses caused by frost, regardless of the temperature itself, also depends on its duration and the phenological stage. Currently, the vast majority of apple trees in Poland are in the mouse ears stage. Although there is already a little more green tissue in Ligol and Idaret, the phenological stage should be slightly generalized on a national scale.

For the mouse ear stage, the temperature should drop to at least -5 ° C. At that time, scientists observed 10% of bud loss. In order for large losses to occur economically, which limits the yield, the temperature must be lowered much lower. 95% of damaged buds were recorded in the prophase of mouse ear only at -9.4 ° C.

With the development of buds and then flowers, the sensitivity to negative temperatures increases gradually. Both apple and pear trees are most sensitive to freezing temperatures during the flowering period and at the start of fruit formation. Then, in the case of apple trees, 95% of damage was found at -3.8 ° C, and in the case of pears -4.4 ° minus.

Temperature and damage

Source: Michigan State University

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