One of your many jobs as a grower is learning about and watching for plant illnesses, one of which is verticillium wilt.
This soil-borne root illness can wreak havoc on your garden, and doesn’t discriminate on the types of plants it infects - anything with roots is fair game.
Early detection of this fungus in your garden can be the difference between salvaging remaining plants and having to scrap the entire grow.
We’ll teach you how to identify verticillium wilt before it’s too late, and share some ways to prevent it from ever coming to your garden.
We’ll also explain how to eradicate it if you do end up in a battle against it. But first, let’s begin by talking about what this fungus does.
What is verticillium wilt?
As we briefly mentioned already, verticillium wilt is a type of fungus that affects your roots and as you may guess, causes your plants to wilt.
The most common type of Verticillium wilt is Verticillium dahliae, but there are five similar species in the same genus which can cause wilts, including Verticillium albo-atrum and Verticilliumtricorpus.
This fungus is a soilborne disease, and exists throughout the temperate and tropical zones across the world. Here is what it does to your plants.
What does verticillium wilt do, and how can I tell my plants have it?
This fungus attacks your plant’s roots and the underground stem, before moving into the vascular tissues of the stem and branches.
This results in blocking the water and nutrients uptake for the plant. This blockage leads to a change in the leaf color from green to dark brown and eventually, to yellow.
The affected leaves fall from their branches, and branches start withering. Initial signs of damage are noticed on the branches facing the shade, as those with the most sun can withstand damage for longer.
Discoloration appears on some plants in patches before spreading to the entire garden rapidly. This is followed by the general wilt and death of the plant altogether.
Some plants may show symptoms of the disease at the time of flowering and collapse suddenly. A brown discoloration or streaking may be seen in the cross-section of plant tissues.
The wilting becomes more significant during the hottest time of the day on the foliage under shade.
There are a few species resistant to this fungus, however. Some include Celery, Asparagus, Oleander, Citrus, Lettuce, Peas, and Beans.
What causes verticillium wilt?
Verticillium wilt can be cause by a number of things, but usually, it is the result of inadequate growing conditions.
Poor soil conditions are the most common cause, as verticillium wilt loves heavy, alkaline soil.
Or, perhaps the fungus spores were carried to your soil via wind, rain, insects, animals, or by you, bringing in infected plants without knowing it.
Comparison of Symptoms Between Verticillium and Fusarium Wilt
Sometimes it can be difficult to distinguish between verticillium and fusarium wilt, as the symptoms and types of fungus are very similar. Here are some key differences to help you determine which wilt you’re dealing with:
- Verticillium wilt is often observed in a cool and humid environment, while Fusarium wilt thrives in hot & dry conditions.
- Plants in alkaline soil are more susceptible to Verticillium wilt, while those in acidic soil are more susceptible to Fusarium wilt.
- Verticillium wilt is more active in heavy soil while Fusarium wilt spreads better in sandy soils.
- Verticillium wilt doesn’t transmit through seed while Fusarium can.
Preventing verticillium wilt in your garden
This fungus lives in the soil so it can be quite difficult to fully control. But, there are a few preventative measures you can take to mitigate the chances your grow can be overtaken.
Healthy plants are harder to infect. So, try to increase the vigor of your plants by feeding them a balanced, well-rounded plant nutrient package, filled with micronutrients and secondary nutrients.
Handle your plants carefully, such as during transplant, to avoid injury to roots and foliage which can create an opening for verticillium to infiltrate.
You should also rotate your plants in the garden between growing cycles, to avoid planting the same plants in the same spot over and over.
You can even seek out resistant varieties of vegetables, fruits, ornamentals, and woody plants in your garden. USDA and the University of California has a complete list of plants that are resistant to verticillium wilt.
Carefully examine the plants brought from the nursery and keep them under observation for a few days before planting in your garden.
Water in the morning so that the runoff evaporates before the sunset, cutting back on the likelihood of mold or fungi growing in your soil.
On that note, one of the most simple steps you can take to decrease your chances of dealing with this disease is keeping good drainage in your soil.
Also, make an effort to amend your garden soil with healthy dry amendments.
Organic fertilizers are more advantageous in building and enhancing the soil organic matter, creating an ecosystem in the root zone capable of battling fungi and diseases.
Control of Verticillium Wilt
If you still find yourself battling verticillium wilt, don’t fret. We have some tips to help you regain control of your garden.
First off, it’s unlikely a fungicide will help you with this type of fungus. Verticillium tends to live deep within the soil, and is hard to eradicate all of it through root drenches.
You can make simple corrections to at least control the rate at which it spreads, or harms your plant.
Implement pruning and cut off infected leaves or the entire plants on the first appearance of disease signs, and safely remove them from the growing space.
You can also double your plant spacing if you are frequently facing Verticillium wilt issues from the last two years or more, decreasing the ability for it to jump from plant to plant.
There are also some unique techniques you can try, that many growers have had success with.
Solarization Control Technique
Solarization is the no-pesticide method to control diseases, pests, nematodes, and weeds. It’s really simple, and doesn’t require much expertise.
This technique involves exposing your garden soil to direct sunlight for 5-6 weeks, and allowing the UV rays to do their thing.
Start by digging up your soil so a few feet of ground is exposed to the sun. then, wet the ground, and cover it with a plastic tarp.
Watering the soil before covering it with a sheet greatly helps in the complete disinfection of the soil.
This technique considerably reduces the chances of all types of wilt.
Remove infected plants quickly and carefully
If your plants fall victim to this illness, you need to pull them from the ground and remove them as quickly and carefully as possible.
Keep in mind that disturbing your root zone too much when removing plants from the garden will shake loose the fungus spores, spreading the disease.
Consider growing hydroponically
If you loose a crop to this soil borne illness, it can be tough to bounce back.
One option is to forego the soil altogether. Instead, opt for a hydroponics system!
These prevent many of the plant diseases you’ve heard about, because there is no soil present whatsoever.
It’s the cleanest, most efficient style of growing there is.
You can check out our Hydroponics 101 guide for a detailed overview of this method, or head over to the hydroponics section at Hydrobuilder.com!