Heat and frost

Autumn and spring frosts:

Young shoots are sensitive to early frosts (October-November), as the cold adaptation of these shoots is late.

A severe autumn frost (down to -6 or -8°C) can be damaging, especially to young trees. This can result in "toad-skinned" bark. Trees that are already weakened are particularly susceptible.

As most chestnut trees are late budding, they are less exposed to late frosts (April-May). However, on hybrids, the risk of frost is important, especially on early budding varieties, particularly in regions where the rapid warming of the temperature in spring is followed by late frosts.

Trunk frost and sunburn:

Heavy frost can result in the development of cortical necrosis. The dehydration of xylem cells due to frost (or heat) induces contradictory torsional forces that lead to the formation of lesions on the trunk. These twisting forces result in a radial split along the trunkwhich may be associated with black oozing on the bark.