Despite the recent rains, it has been another parched year here in the Golden State. Water restrictions, fire warnings, wildfires…you name it, we’re in the thick of it. And this drought is not doing our urban forests any favors. So you would think that more watering would help the trees. However, in some cases this can be too much of a good thing.


Of course, water is essential for tree growth and health. But depending on the type of soil (clay?) and the kind of watering (sprinklers?), too much water can lead to a number of issues:

  • Root rot: If there is too much water without the proper drainage then there is no pore space for air to flow. Lack of air to the roots can suffocate the absorbing roots and cause fermentation. Signs of this include foul smells and/or black-colored roots.
  • Basal or Butt rot: Signs of this include fungus or bacterial infections on the lower trunk.
  • Cracked bark: Excess water update may case the bark to swell and crack in some tree species.
  • Chronic stress: Too much water can cause stress and affect the tree’s metabolic processes, which can lead to an overall decline in health. Interestingly, the yellowing, wilting and early leaf drop symptoms caused by not having enough water is almost identical to the presence of too much water.

The best this prevent overwatering is to watch your irrigation! Work with your Arborist or landscaper to take a look at your irrigation system. Sprinkler systems are commonly used to water ornamental flowers and lawns. However, sprinkler heads that spray tree trunks and foliage day after day can be detrimental. Drip irrigation systems that add water slowly to the root zones can be a great alternative to sprinklers.

Additionally, adding mulch around your trees can help absorb excess water and reduce water run-off.

Our water in the Golden State is a precious resource. We have to use it wisely to help our urban forests. Save our water. Save our trees.


Written by: Josh Hotai