How To Identify, Control & Prevent Corky Root Rot Tomato Plants?

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In this guide, I will help you easily identify, control, and prevent one of the soil-borne diseases of tomatoes, corky root rot.

Do keep reading for more information!

What Is Corky Root Rot And How Does It Harms Tomato Plants?

Corky root rot is one of the most common soil-borne diseases of tomatoes. It is caused by a fungal plant pathogen, Pyrenochaeta lycopersici that can survive in the soil for many years.

It affects the root system of tomato plants and eventually reduces their yields.

How To Confirm That Corky Root Rot Is Troubling Your Tomato Plants?

One distinguishing feature of corky root rot is stunted growth, premature defoliation, decreased fruit yield, and wilting of the tomato plant. The pattern starts from the top and gradually works down.

There may be smooth brown lesions on small roots if you observe roots.

As the disease progresses, the older roots may become swollen and corky. The branches on mature plants may die from the tips.

Here is a video on corky root rot:

Natural Ways To Control Corky Root Rot On Tomato Plants

Soil-borne corky root fungus is very destructive and not easily identifiable.

There are only a few natural options available but many biological control measures are still experimental. Future studies will offer many feasible options.

Method 1- Amend The Soil With Compost

Organic amendments help in improving soil conditions and suppressing soil-borne pathogens. Preliminary studies showed that amending the soil with various composts, including green manure and garden waste, reduced the severity of the corky root rot.

But, more studies are required to confirm.

  • Amend the soil– Remove the heavily infected parts. Clear the soil of debris and hard clumps. Mix the infested soil with 20% of compost. It helps in reducing the severity of pathogens.

Physical Ways To Control Corky Root Rot On Tomato Plants

Soil solarisation is a pre-planting technique that effectively controls soil-borne corky root fungus. Also, you may trim the heavily infected plant parts.

Method 1- Soil Solarization

Soil solarisation is shown to be effective in reducing many soilborne pathogens. It involves heating the soil by covering it with clear plastic.

The success depends on the amount, depth, and duration of high soil temperature.

  • Prepare the soil– Clear the soil of rocks and surface litter with fewer air pockets.
  • Irrigate the soil– Wet the soil surfaces using a soaker hose to about 12 inches.
  • Lay the plastic tarp– Place transparent or clear plastic on the planting area to trap the heat. The plastic should be held very tightly against the soil. Remove the plastic and plant the transplants.

Check out this video for understanding soil solarisation:

Chemical Ways To Control Corky Root Rot On Tomato Plants

The chemical treatments can be expensive, devastate beneficial soil microflora, and cause environmental damage.

Preplant treatment with metam sodium may reduce disease in the tomato plant.

Method 1- Apply Metam Sodium

Metam sodium is a widely used soil fumigant that is effective against soil nematodes, fungi, and weed seeds. It can be used as a pretreatment plan in fields with a history of corky root rot.

Do not apply when the air temperature is over 90oF.

  • Prepare the soil– Cultivate the area to be treated and loosen the soil. Moisten the soil before treatment.
  • Apply metam sodium– Read the manufacturer’s instructions and apply it to the prepared soil. It is a water-soluble liquid that gets converted into a fumigant. It can also be injected into a mixture of liquid fertilizers.

How To Prevent Corky Root Rot In Tomato Plants?

The growers should follow good gardening practices to prevent corky root rot in tomato plants.

Ensure the seedlings are healthy, and clear the garden debris after harvesting. Practice crop rotation to get rid of these soil-borne pathogens.

Method 1- Practice Crop Rotation

Practice crop rotation to avoid corky root rot in tomato plants.

It is recommended to change the location of planting tomato crops every year. Rotate with non-host crops to prevent corky root rot.

Method 2- Follow Good Gardening Practices

Remove the garden debris after harvest and fumigate the soil to remove the soil pathogens.

Also, wait for planting in the spring until the soil temperatures are about 68oF. Mound soil around the base of the plants to promote adventitious root growth.

Method 3- Use Disease-resistant Variety

Use disease-resistant variety to prevent corky root rot in tomatoes. You may also use grafted tomato plants but it may increase the planting costs.

What Causes Corky Root Rot Attacks In Tomato Plants?

Corky root fungus may survive in the soil for a long time. It may happen through the dispersal of soil particles through contaminated farm equipment and cultivation practices.

 It can also attack tomato plants when planted early under excellent conditions. The disease will develop when the temperature is 60-68oF.

Frequently Asked Questions

Can you use grafted tomato cultivars to control corky root rot?

Many research studies support the use of commercial tomato cultivars grafted onto rootstocks tolerant to fungi. But,it increases the planting costs and so cannot be affordable.

What are the differences between corky root and fusarium wilt?

Corky root rot is caused by the fungus Pyrenochaeta lycopersici and causes the yellowing of plants with weakened growth. Also, the roots appear cracked and dark brown. Fusarium wilt is caused by Fusarium oxysporum which causes rotten roots and discolored stems.

Can you use ammonium fertilizer to reduce the severity of corky root rot?

No, it is preferable to avoid ammonium fertilizers on tomato plants with corky root rot. Pyrenochaeta lycopersici and the corky root rot increase in severity when the ammonium fertilizer is applied.


I hope this guide has provided some great tips for preventing corky root rot in tomato plants. You may follow these tips to prevent future attacks.

Please let me know if you have tried any other method to tackle this disease.

Do share the guide with your friends if you find them helpful!