Problem Identifier / Fusarium Wilt

What is Fusarium Wilt?

Fusarium Wilt Cannabis Plant
Fusarium wilt seen in cannabis plants.

Fusarium is a pathogen located right under the surface of your soil. It can lie dormant for years, waiting for the perfect conditions to attack. Fusarium attacks the root system of your plants, clogging the xylem and preventing your plants from taking up necessary water and nutrients required for health and growth.

The root system is crucial for the physiology of your plants, with any damage resulting in both poor plant health and yields. Once contact is made with the root cortex and the xylem has been penetrated, the plant will be unable to bring nutrients through the stem. Your plants will eventually weaken, wilt, and struggle.

The development of fusarium wilt occurs when the weather is hot and soil temperatures reach approximately 80 degrees Fahrenheit. Fusarium wilt thrives in dry weather when moisture in your soil decreases.

Fusarium can destroy your entire crop. It mostly attacks cannabis, tomato, pepper, eggplant and potato plants. With no cure or treatment, understanding how to prevent it is important which we will go into more detail below.

Symptoms of Fusarium Wilt

To diagnose fusarium wilt, you need to look for specific symptoms. Despite some of these symptoms indicating a nutrient deficiency, if several are present there is a good chance your plants are suffering from fusarium. The key symptoms include:

  • Wilting and yellowed leaves
  • White, pink or orange growth of fungus on the outer stems
  • Stem and root decay
  • Necrotic tissue and decay spreading up your stems
  • Red discoloration of the roots right under the soil
  • Stunted or slowed overall growth
  • Swelling stems eventually splitting open due to the pressure
  • Dissecting the stems reveals a reddish discoloration

What Can Fusarium Wilt be Mistaken For?

Fusarium Wilt Soy
Root symptom of fusarium wilt in a soy plant.

Fusarium wilt is often mistaken for Phialophora cyclaminis, another vascular plant tissue disease. The two are easily confused since both cause the leaves to become deformed and yellow. The cross-hatched or blistered appearance is like fusarium. A fusarium infection is also confused with Erwinia carotovora. This is a bacterial type of soft rot also causing the stalks to rot.

Once the plant tissue dies, the dark brown coloration is nearly identical to the fusarium wilt. Another area of confusion is nutrient deficiencies. Manganese, nitrogen and potassium deficiencies result in yellow leaves. A potassium deficiency also causes slowed plant growth. Due to the impact of fusarium wilt, nutrient deficiencies in your plants during the process of the disease are common.

Fusarium Wilt Treatment

Unfortunately, there is no cure for fusarium wilt. The only option is preventing fusarium in your plants. Once your plants are infected, they must be removed and destroyed. To prevent the spread of fusarium, make certain all tools contacting your infected plants are thoroughly cleaned with hydrogen peroxide before using them for your other plants.

How to Prevent Fusarium

If your outdoor cannabis or vegetable crop has been infected with fusarium, you will not be able to grow in that area in the future. You can grow other types of plants without any issues. Do not use any of the seeds from your infected plants because the disease will remain dormant. As soon as your seedlings emerge, they will be affected by fusarium wilt.

Certain types of soil are more resistant to fusarium attacks than others. The high pH resulting from the funganistic properties of clay soils are more resistant. These types of soil are also excellent for growing cannabis. Loamy soils containing diverse and healthy plant growth often contain native microbes capable of suppressing fusarium. These types of soil will not stop fusarium but often slow the progress. By combining them with other measures, you can often prevent fusarium.

Apply beneficial bacteria including Bacillus subtilis, Bacillus pumilus, Streptomyces griseoviridis or Gliocladium as a foliar spray, soil drench or pretreatment for seeds for fusarium prevention. Mycorrhizal fungus colonization can reduce the disease index significantly by suppressing pathogen development.

Fusarium Wilt Cannabis
Fusarium symptoms seen in the bud of a cannabis plant.

You can prevent numerous types of fungal infections including fusarium wilt by using compost tea or correctly aged compost. One of the most effective ways to prevent fusarium is container gardening because you have 100% control over your soil. If you have an area ideal for growing due to sun exposure or weather that was infected in the past, you can still take advantage of the conditions by using containers for your plants to prevent the disease.

Use new or sterilized pots and pasteurized or sterilized soil mixes to prevent fusarium wilt. Make certain your soil drains properly and you are not over-fertilizing. Do not allow the pH in your soil to drop too low. You can use greensand or dolomite for the neutralization acidic soil.

Use a fertilizer enhanced with calcium and potassium to help prevent fusarium wilt. Avoid fertilizers with excess phosphorus and nitrogen or you can enhance conditions for the disease.

How to Prevent Fusarium Wilt on Tomatoes

One of the best preventative measures for fusarium wilt on tomatoes is planting tomato plants with fusarium wilt resistance. The tags on these plants are labeled FFF, FF or F. This is in reference to the three different types of fusarium wilt. Solarizing your soil can also prevent fusarium wilt. Use a sheet of plastic to cover your soil to substantially increase the temperature for a long period of time.

The higher temperature of your soil will eliminate fusarium wilt, making it safe for planting. Soil solarization is not effective in every area, so it is a good idea to speak with a local expert. Your boots and gardening tools must be kept clean. If contaminated, your shoe soles and tools can spread fusarium wilt pathogens to healthy soil.

Does Peroxide Help with Fusarium Wilt on Tomatoes?

Yes, using hydrogen peroxide will help with fusarium wilt due to the reaction with other molecules. The peroxide will permeate your soil and slow fusarium wilt.

What Tomato Varieties Resist Fusarium Wilt?

You should not have any difficulties finding tomato plants resistant to fusarium wilt. The most common varieties include Big Daddy, Summer Girl, Early Girl, Sungold SuperSauce, Porterhouse Rutgers and Yellow Pear.


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