Root Rot After Heavy Rainfall

Oct 14, 2016

Ask any tree expert and they will tell you that one of the common risks of heavy rainfalls is root rot. This issue can develop from heavy rains, overwatering plants, or any other situation in which they get too much water. There are a range of various rots that ornamental shrubs and trees can develop, including root rot. An incredible range of plants can develop root rot, including houseplants as well as outdoor plants whether they are shrubs, trees, tomato plants, or something else.


There are two main causes of root rot, but it more likely to occur in warm soil that is full of water. It can happen because of a prolonged exposure to too much water, such as if the soil drains poorly following a heavy rainfall. This can cause some roots to not get enough oxygen and die back. That in turn leads to them decaying and rotting after they die. The rot will eventually spread to healthy roots and kill them and this may even occur if you fix the soil conditions, such as encouraging drainage in the area.

Root rot isn’t always caused by constant heavy rainfall or overwatering; sometimes it is due to fungus. In the case of root rot caused by fungus, the fungus can actually be in your soil for years. It will then come alive if the plant becomes overwatered just one or two times. The fungus causing the root rot will attack the roots, making them die and rot. Since Texas isn’t known for constant heavy rainfalls, root rot caused by fungus is more likely. If there is a heavy rainfall or two in the area, this may trigger the fungus within the soil to wake up, making it seem as if the recent stormy weather caused the rot.

How Do I Know If My Trees Have It

Although there are a few varieties of root rot that can affect your plants following heavy rains, the signs are pretty similar. As with any other root disease, you will notice that the leaves seem as if they have been stressed by a drought. They may also die quickly when late spring and early summer arrives and the temperatures rise.

All types of root rot share some symptoms, such as the leaves being smaller than normal, wilting, or becoming yellow or brown. The plant may just seem as if it is gradually getting less healthy without you knowing why. If you look at the roots and crowns, you may notice damaged areas that are black or brown.

Specific Types

In the case of Phytophthora root rot, the leaves of trees with root rot will wilt and turn purple, red, yellow, or dull green in color. It is possible for a tree with an infection to survive for several years. During that time, the bark by the soil line may have darkened in color. If you happen to cut away a bit of bark, you will notice the wood underneath is red to brown.

In the case of fusarium root rot, the plant’s foliage will also wilt and turn yellow while the plant dies. You are likely to first notice the symptoms on mature leaves. Some plants will also develop corky root rot, which is less aggressive. This type of root rot will reduce the plant’s vigor but not actually kill it.


It is fairly easy to diagnose root rot following a heavy rainfall. If you notice the symptoms mentioned above, look at the roots of the plant in question or have an arborist do so for you. If the roots feel mushy and are black, they are infected with root rot. They may even fall off your plant when touched. If the roots appear pale or black, but are pliable and firm, root rot is not the culprit.

Ways To Reduce And Prevent

If you suspect that any plants on your property are suffering from root rot, contact an arborist to help you treat the tree in question and determine whether it needs to be removed. One of the most important courses of action is to ensure that the area gets adequate water drainage. This can prevent the root rot from worsening and stop it from affecting other plants on your property at the next heavy rainfall. Sometimes, removing soil from the crown of your trees can also help. You want the root flare to be exposed since fungal infections are most common in that area.

Ideally, you will set up your saplings in such a way that the water drains away from them so this is never an issue during their lives. If you can, you should also consider going with a raised planting site, such as a mound of soil, as this will raise the plant’s roots and minimize the amount of water that pools after heavy rains.


The best way to treat root rot is unfortunately to remove the plant and then destroy it. This will be your only option in the case of severely infected plants, but some moderately affected ones can survive. To treat those, you would have to replant the tree or shrub in dry soil that is well-drained to prevent a repeat occurrence at the next rainfall. You can then use clean shears to prune away the diseased roots along with the top third to half of the plant’s growth.

It is crucial to prune the top portion of the plant as well, even if it appears health. This reduces the amount of stress placed on the remaining roots. Since you are removing some roots, the remaining ones would have to work harder to support the same amount of tree; trimming the top prevents this. Be sure to disinfect your tools and shears between cuts to prevent the root rot from spreading.

To be safe and give your tree or other plant the best chance of survival following a rainstorm, contact an arborist as soon as you suspect root rot. They will be able to tell you whether the plant can be saved and guide you through the process of doing so.