Guide to Preventing Verticillium Wilt in Cannabis Plants

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Verticillium wilt in cannabis
Author avatar By Parker Curtis
March 25, 2022
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Marijuana cultivation poses many challenges. While you can eliminate many pests and diseases by maintaining an ideal environment, dealing with verticillium wilt in cannabis plants can be tricky. The infection can hit your crops unexpectedly, causing them to wither and die. 

As the symptoms of the affliction are similar to other maladies, knowledge, and prevention are your main defenses to enjoy a trouble-free and fruitful experience. Learning to identify signs of the potentially deadly menace and how to protect your plants from an imminent attack will save you heartbreak.

We’re about to explain what verticillium wilt is, how to notice the signs and whether you can get rid of it. We’ll then offer some tips for how to prevent it. Ready to know more? Read on.

Verticillium wilt in cannabis leaf
Verticillium wilt in the cannabis leaf

What is verticillium wilt?

Verticillium is a fungus in the soil that causes disease in crops. The scientific name is verticillium dahliae, and it thrives in humid areas with an average temperature of 68-82°F. Vegetation in nutrient-rich soil with improper drainage and stressed plants is most vulnerable to affliction.

The fungus can inflict extensive damage to cannabis plants by infecting their roots and spreading to other parts through the xylem. It releases toxins and creates a blockage in the vascular tissue, preventing the plants from getting water and dissolved nutrients through the leaves and stems. 

Verticillium wilt in cannabis plants causes the leaves to turn yellow and wither. Crops have no chance of survival, and ultimately, the foliage turns gray and dies. The fungus can exist in the infected soil for many years, rendering the area unsuitable for cultivation.

While there are ways to treat crops affected by cannabis pests, and many plants can heal, it’s not the case with the verticillium fungus. Currently, there aren’t any effective measures to deal with it after it spreads. Prevention is the only solution.

Many commercial farms resort to fumigation to stave off infection. This measure is drastic because the chemicals harm the environment, but farmers fear losing crops. It’s best to use less damaging measures such as soil solarization and crop rotation to protect your plants.

Before learning how to prevent verticillium wilt in cannabis plants, it’s essential to know the signs to identify them before verticillium wilt spreads.

What are the signs and symptoms of verticillium wilt in cannabis plants?

An excellent way to protect your crops from verticillium fungus is by monitoring them daily and noting any changes in their appearance and growth. First, it’s important to learn to identify the telltale symptoms that indicate a fungus infection is in progress.

One obvious sign is the foliage near the plant’s base turning yellow. The discoloration is prominent on the outer part of the leaves and between the veins. Notice that the stem turns brown at the soil line. Verticillium wilt in cannabis crops causes the leaves to turn grayish-brown before the plants ultimately wilt.

It’s important not to confuse fusarium and verticillium wilt when looking for infection signs because the symptoms are similar. One key difference is that the former occurs in warm weather, while the latter is a cool-weather disease. 

Marijuana plant dying of verticillium wilt
Marijuana plant dying of verticillium wilt

How to get rid of verticillium wilt

After learning to identify the signs, the question is whether you can treat infected plants. The current consensus is that you can’t do anything to prevent them from dying. It’s vital to know how to get rid of verticillium wilt to protect the rest of your crop from the ailing ones. 

When you confirm that the fungus has taken over your plant, remove it immediately from your grow area. Dispose of the diseased herb to stop the spread and destruction of your other crops. Exercise extreme caution during the extraction process as verticillium proliferates through spores which can transfer airborne to healthy crops. 

Make sure you don’t put another plant in the same soil, as it’ll also experience verticillium wilt in cannabis plants. Prepare a sterile container with a new potting mix and transplant the other herbs. Observe them for infection signs. Hopefully, there aren’t any because if the fungus has attacked the plants, there’s no chance of saving them.

If you use containers, be sure to sanitize the pots and tools before growing again after an infection to avoid repeating the problem.

How to prevent verticillium wilt in cannabis plants

Currently, there are no proven ways to treat verticillium wilt and heal your plants, so executing preventative measures is the best option for marijuana growers. These steps involve expenditure and effort, but they’ll reduce the possibility of losing your crops to the fungus.

Cultivate hardy marijuana strains

Every successful growth process begins with the seeds. To protect your plants from the verticillium fungus, choose cannabis strains resistant to diseases and pests. Most of these cultivars can develop into healthy plants under harsh conditions.

Beware of fraudulent online sellers who may offer fake strains with mediocre genes. Avoid the heartbreak of growing duds or end up with sickly plants by getting high-quality seeds from established vendors like us here at Homegrown Cannabis Co.

These premium-grade seeds may cost more, but they’re usually free of harmful pathogens. You needn’t worry about verticillium wilt in cannabis plants and dumping your crops with proper care and maintenance.

Utilize high-quality soil

Besides using superior-grade seeds, it’s essential that you grow them in high-quality soil or potting mix. These mediums are rich in the nutrients your seedlings need to develop into robust plants resilient to pathogens such as the verticillium fungus.

The price you pay for the best soil for outdoor weed is nothing compared to the risk of infection. How you utilize the medium is equally critical to getting excellent results. 

If you end up with verticillium wilt in your cannabis plants, you must immediately ditch them and the soil used. Don’t reuse the medium because the fungus can remain active for many years and infect future crops. 

High-quality soil for weed
High-quality soil for weed

Ensure proper drainage

Adequate drainage is essential to prevent disease as most pathogens, including the verticillium fungus, thrive in warm and humid environments. Ensure that excessive water doesn’t accumulate in the soil. Adding perlite and compost can help amend the medium.

For outdoor cultivation, check that the water drains downhill. Avoid pools that cause your soil to be soggy. If your terrain is flat, an excellent remedy is building a French drain with a 1–3% gradient to facilitate the removal of excess liquid

Soil solarization

There are ways to protect your crops from the verticillium fungus without the need to fumigate. Using a natural fungicide for plants is an ideal alternative to heavy chemicals that can harm your plants’ health.

An excellent environment-friendly and reliable method of preparing the soil to mitigate or eliminate threats before you plant your seedlings is soil solarization. This practice uses the sun’s rays to kill the following microorganisms:

  • Fungi, such as the verticillium fungus
  • Bacteria
  • Mites
  • Nematodes
  • Insects
  • Weed and Weed Seeds

To implement the method, till the soil, mix in compost, and add water before covering it with a transparent polyethylene tarp. The idea is to trap the sun’s energy and let the high temperature cook the microbes for at least three weeks. The best time is during sunny and hot periods.

Outdoor cannabis under the sun
Outdoor cannabis under the sun

Crop Rotation

A time-tested cultivation practice that marijuana growers use to prevent diseases such as verticillium wilt in cannabis plants is crop rotation. If you’ve encountered fungal infection, there are several cover crops you can cultivate when you diversify, such as broccoli, mustard, or sudangrass.

After growing these fungi-resistant plants, you can solarize the soil to stamp out the harmful microorganisms and cultivate cannabis again.

Use a hydroponic setup

As the verticillium fungus affects crops grown in soil with poor drainage, you can avoid the infection risk by cultivating hydroponic weed. 

Besides eliminating the need for soil preparation and maintenance, gardeners prefer this setup because it has many benefits like faster growth and bigger yields. Pests and diseases are also easier to spot.

This method is perfect if you live in a warm and humid location as you can control the environment such as light and temperature

Healthy cannabis plant outdoors
Healthy cannabis plant outdoors

The welcoming news about verticillium wilt

It’s daunting for cultivators to learn that marijuana plants infected with the verticillium fungus have no chance of surviving. While the disease is deadly and there aren’t any effective treatments, there’s no reason to fear losing all your crops.

Knowing the infection symptoms is vital. With early detection and immediate removal of affected plants, you can save the rest of your crops. Learning how to prevent verticillium wilt in cannabis plants will reduce the risk and give you some peace of mind.

Remember to use hardy cultivars and ensure you get them from trusted sources like us. Browse our website for quality seeds. We also offer a seed replacement guarantee and secure ordering. Be sure to join our forum to get more cultivation tips and advice. 


About the author: Parker Curtis

Parker Curtis has around a decade of cannabis-growing experience, specialising in soil-less and hydro grows. He’s mastering outdoor, greenhouse, and indoor grows.