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Creating Optimal Conditions to Avoid Root Rot

Root rot can be devastating to a landscape. Make sure you know how to properly protect your customers’ lawns.

July 28, 2023

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preventing root rot

Although root rot is most common in house plants, trees and shrubs are susceptible too. 

Root rot is a debilitating disease that can spread throughout a landscaped area from trees to shrubs to other herbaceous material quickly if not addresses early on. Thankfully, it’s easy to spot and something you can control to a certain degree.

Although once a plant gets root rot, you can’t ‘cure’ it, there are steps you can take to reduce the risk of this invasive disease taking down a landscape. Here’s how you can manage it.

Why root rot shows up

In order for root rot to rear its ugly head, the landscape needs three things. Known as the Disease Triangle, your plants are more susceptible when there’s:

  • A root rot pathogen - Phytophthora spp. and Armillaria Mellea are the most common
  • A susceptible host - Stressed plants in particular
  • The right environmental conditions

The pathogen begins in the soil, looking for a host. It can wait a while within the soil for a vulnerable plant, making the pathogens themselves nearly impossible to eliminate from an infected area.

The first signs of root rot appear as trees or shrubs within the landscape start to turn brown. Some plants may even die before you’re able to remove them.

Although it’s the pathogens that cause all the damage, targeting them is not a surefire way to reduce the risk of root rot. It’s best to focus on the other points of the triangle — the host and environment — when dealing with root rot.

Reduce stress on trees and shrubs

Plants can become stressed when:

  • Not properly planted
  • Are over- or under-watered
  • Get too little sun
  • Are over-fertilized
  • Planted in the incorrect soil acidity

Each of these issues can easily be remedied, however it may not be until a plant shows signs of stress that you become aware something is wrong. When a plant feels stress, you may see signs of:

  • Dead wood
  • Sparse or wilting leaves
  • Dropped branches or dead bark
  • Fungal bodies on the plant
  • Sprouts or suckers also known as witches’ broom

To reduce stress, make sure you’ve planted in the ideal location based on the plant’s cultural needs. This space should also have enough room for the roots to spread out. For a tree under stress, make sure the root flare is at or slightly above the soil level. 

If you need to transplant a stressed plant to more optimal conditions, make sure to only lightly mulch after to ensure good air flow to the roots.

Stressed plants aren’t the only ones more susceptible to root rot. Younger trees and shrubs also run a higher risk since they have softer roots. Their natural defenses aren’t as strong yet either, leaving them more vulnerable. Planting young plants in optimal conditions may reduce their risk though.

Create the right environment

Any unbalanced environment can increase your risk for root rot. This is why conducting a soil test is so important before you plant. Knowing what you’re starting with makes it possible for any soil amendment to take place before putting vulnerable plants into the ground.

Conditions in the environment that can increase the risk for root rot include the soil being either too acidic or too alkaline as well as when water levels are too high. This can occur if soil drains poorly, especially in low-lying areas made up of mostly clay or compact soil. To stay on top of watering, you may need to install a smart controller to the existing sprinkler system or create better drainage.

Balancing the soil composition with the help of a soil test is the first step. Adjusting watering levels or drainage to suit the space will then address the second issue.

Add plant diversity

Another way to reduce the risk of root rot spreading among a landscaped area is to diversify your plant life. Many diseases favor specific plant varieties over others, and a diverse selection of trees and shrubs will naturally provide the landscape with more resilience.

Some particular tree varieties targeted most by root rot include, oaks, beech, dogwood and fruit trees, while small-leafed evergreen shrubs are less likely to have issues at all. You can consult a SiteOne local branch associate for help identifying the best local options to diversify your landscape.

Remove the diseased plant

Even in the most optimal conditions, should a plant succumb to root rot, you must remove the diseased and dying plant completely. This includes any stump, if you’re dealing with tree root rot, and all the roots of the affected plant. Leaving any piece behind increases your chances of another plant within the landscape getting root rot as well.

Give your landscape the best odds to stay healthy

Taking care to address common diseases like root rot before they happen means being thoughtful and intentional when creating any landscaped area. For more tips and all the essential supplies, SiteOne is here to help. Check us out today at and on our mobile app.

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