Plant diseases


The Bold is one of the diseases that most often have plants, especially when they are suffering a major attack mealybugs. It is also one of the best identified, since the symptoms it produces are very characteristic.

Although it may seem otherwise, it is easy to control if we take a series of measures. So if you want to know everything about this disease, then we invite you to continue reading.

What is it?

Image – Wikimedia/ Bidgee

The bold or sooty mold is an opportunistic fungus, which means that it will appear only when the plant is being weakened, which is just what happens during the attack of a pest, but beware, not just anyone, but mealybugs, whitefly and aphids. Unfortunately, almost all plants can be affected by these insects, so they must be closely monitored and controlled to avoid problems.

But what is the disease characterized by? Well, it’s simple: by the appearance of a sticky black powder that covers the surface of the leaves. With this, it prevents photosynthesis from being carried out, and in very serious cases in which it covers them completely, it also stops breathing by clogging the pores.

What are the symptoms and/ or damages?

Apart from what we have already said, we will see the following:

  • Pests: mealybugs, whiteflies and/ or aphids
  • Premature leaf drop (defoliation)
  • Growth slowdown
  • General appearance »sad»

But we don’t have to worry too much: most of the time it can be controlled easily, thus avoiding that the pest in question ends up in the compost heap.

How to prevent?

We can do several things to prevent bold, which are:

Prevent pests and fight them


If we prevent pests we will be able to prevent the black fungus. But how do we do this? Well, although there are people who say that what I am going to comment below is not credible, I am one of those who are convinced that a healthy and well-cared for plant is a plant that will hardly fall ill. So so that the insects that we have been mentioning do not attack it, I will recommend the following:

  • Buy plants that can live well in your area: believe me, if you get, for example, a Japanese maple and you live in an area with a very warm climate, that tree will have to fight day in and day out to stay alive. In the end, his health will weaken and that is when the insects attack him. And from there to the bold appears… there is only one step.
  • Water as much as you touch, neither more nor less: it is true that irrigation is one of the most difficult things to control, but it is all a matter of observing the soil and practicing. Find out what water needs your plant has, and then adapt them so that it can be really good. For example: we know that geraniums need frequent waterings, like 4 or 5 times a week in summer and once every -34 days the rest; but if it rains very often in our area, that irrigation frequency will be less. When in doubt, always check the soil’s moisture, either by inserting a thin wooden stick or using a digital moisture meter.
  • Fertilize throughout the growing season: plants – with the exception of carnivorous ones – need a regular supply of fertilizer during the warm season. Therefore, do not hesitate to stop by this post to know what types there are.
  • If they are potted, transplant them: when the roots run out of space, health is also weakened. Avoid this by transplanting them every 2 or 3 years.


In the event that they already have pests, we must act by doing any of these things:

  • Clean the sheets are a brush soaked in pharmacy alcohol.
  • Treat with potassium soap, which is a non-toxic natural product that must be diluted in 2% water and sprayed/ sprayed on the plants.
  • If the pest is serious, treat with specific insecticides following the indications specified on the package.

Keep diseased plants separate from the rest

When our beloved plants already have bold, what we have to do is take them or keep them separate from the rest to avoid contagion. In addition, it is very important that we wash our hands and tools well before and after handling them for the same reason.

How to eliminate the fungus?

Image –

To eliminate it, we first have to thoroughly wash the affected parts with a cloth, or if we want with a brush. We will see that the scab goes away relatively easily, so that in principle with this and as long as the size of the plant in question allows it, we will not have to do anything else.

Now, if we want to protect them even more, or if they are large plants, we can treat them with potassium soap or with fungicides based on copper or sulfur.

And with this we are done. As you can see, bold is a disease that can cause a lot of damage but it is easy to control .

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