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What is Verticillium Wilt Fungus?
Verticillium wilt fungus is not a common disease, and when it does occur, unfortunately, it’s untreatable and can be very damaging to your plant. It’s also a little difficult to identify correctly because symptoms such as yellowing and wilting leaves are also common symptoms of many other diseases too. However, there is a way to tell which I touch on in more detail below.
This fungus spreads through the soil and enters the plant via its roots. It moves upwards through the plant causing water stress. This fungal infection can be present throughout the entire year but develops quite rapidly in warm weather.
How can you recognise Verticillium Wilt Fungus?
As I have already mentioned, it’s not always easy to recognise this disease because most of the first indications there is a problem are underneath and inside the plant. It attacks the roots, which then causes, wilting, and discolouration of the leaves, especially the lower ones, and then the stem eventually dies back. Not all of the plants may die but many do succumb to this fungus. Some can be recovered using a feed to encourage new growth, more on this below.
However, if you cut through the affected parts of the plant, there are usually black streaks inside the stems, under the bark, and circular patterns in the branches with black in them. It is vital that you thoroughly sterilise any cutting tools you have used afterward. One important thing to note is that not all plants show these signs of infection though, but it’s a good reliable indicator if it does.
What can I do about this fungus?
Preventing Verticillium Wilt
Keep your plants in environments that are best suited for their strong and healthy growth. It is difficult to say any one thing can prevent it. It’s more about growing healthy strong plants in suitable conditions so they are stronger to resist the disease.
Cut off all the diseased parts of the plant and encourage new growth. Feed the plant with a fertiliser high in nitrogen applying it around the base of the plant once or twice during the growing season. Work the fertiliser into the soil and water in. Additionally, if possible, change the environment around the plant to be cooler and wetter, being careful not to cause poor draining soil as this can lead to root rot. Plus, most plants don’t actually like having their feet wet.
If the fungal disease continues to spread, you will need to get rid of the entire plant and the surrounding soil. Unfortunately, once it’s in the soil, you have two options, the first is to grass over the area and avoid planting anything else there for at least 10 years because the soil may still be contaminated. Another option is to plant something that is resistant to Verticillium Wilt, examples of such plants include most conifers as well as grasses, but also trees including Birch, Salix, Cercidiphyllum, Gleditsia, Liquidambar, Crataegus, Fagus, Morus, Platanus, and Salix.