Overwatering (excess of water)

Excessive water, whether temporary, regular or permanent, causes anoxia, which quickly leads to the death of fine roots and then, if it persists, to the death of the larger roots. The consequences depend on the proportion of the root system affected and range from loss of growth in a given year to the death of the tree in extreme cases. Root growth is retarded, leakage of amino acids from the roots to the soil increases, mycorrhizae development decreases and anaerobic bacteria bind nitrogen and sulphur under these conditions, which will hinder the tree’s nutrition, and it will express deficiency symptoms.

The chestnut tree is really intolerant of excess water and poorly drained soils.

Excess water in the soil at regular intervals:

Particular site situations can favour excess water. They often combine topographical positions that lead to water accumulation in the soil (bottom of slopes, basins, etc.) and poorly filtering materials (because of their structure or texture). In areas with permanent hydromorphy, the minimum depth of the water table will be a limiting factor for the installation and development of trees. Soils with temporary hydromorphy are generally waterlogged during very wet periods in winter, but very dry during hot summer periods. This contrasting regime strongly limits root exploration.

Temporary excess of water:

Abnormally heavy rainfall at the beginning of the growing season can lead to temporary waterlogging of stations that do not allow for rapid water evacuation. Local mortalities are then observed during the following summer.