Why does my plant have black spots on the leaves?

Black spots on the leaves

Image - Flickr / Agronomic Planet Archives

Does your plant have black spots on the leaves and you don't know why? Don't worry: we are going to tell you what the possible causes are and what you can do to make it look healthy again.

If it is not treated, the plant simply cannot move forward, that is why you have to act as quickly as possible.

Palm trees are generally green

Plants have managed to adapt to the specific conditions of their habitats, but when cultivated they can become somewhat weak, especially if they are exotic or have been 'pampering' themselves too much and / or for a long time.

However, it is important to bear in mind that if they are well cared for, that is, if they receive only what they really need, it will be difficult for them to get sick or have problems. In fact, weaknesses begin to appear especially when they are watered in excess or under water, when they do not receive the amount of light they need, and / or when they are pruned with tools that have not been disinfected before use.

Based on this, why do black spots appear on the leaves of plants?

Leaves can be claw-shaped
Related article:
What do the downward claw-shaped leaves mean?

Causes of the appearance of black spots on the leaves

There are several reasons why we can end up having our beloved plants with black spots. Some are easier to treat than others, but we need to know them all:

Bold

Bold in sheets

Image - Wikimedia / Bidgee

It is a fungus that mainly affects the leaves when the plant is exposed to excessive humidity, for example, when it is sprayed daily or overwatered. But this disease does not usually appear "just because", but because of aphids. These are insects of less than 0,5 cm that are attracted by the sweet taste of the leaves and flowers, so if we want to treat the disease we will have to eliminate them first. How?

There are several methods: with a yellow sticky chromatic trap placed near the plant, with neem oil, or with chemical insecticides such as pyrethrins. Later, We can treat with fungicides such as copper or sulfur so that the bold disappears.

Burns

Sunburns, including those caused by the magnifying glass effect, can cause black spots to appear on the leaves. For this reason, you never have to place a plant in direct sunlight if it has not acclimatized before, and it is not a good idea to water during the middle hours of the day.

What to do? Place the plant in semi-shade and gradually expose it to the sun, only if it is a heliophilic species (that grows in the sun). In addition, it should not be watered »from above», because if we do we could burn it.

Frequent spraying and / or watering 'overhead'

When we spray / spray the leaves of the plants with water in a continuous way we can cause their rot. It also happens when we water from above, that is, if instead of directing the water to the ground we direct it to the same plant.

This for doing it once nothing will happen, but if we take it out of habit in the end we will make its appearance worse. So to prevent this from happening, it is best not to. You always have to water the land and not the plant, and in the case of seedlings, we can water by the tray method.

Natural death of leaves

Leaves, even perennials, have a limited life expectancy. Depending on the species, this can be a few months, or last up to a few years. That is why if we do not detect any pest or disease, and if it looks healthy, we will not have to worry.

The black spots on the foliage sometimes simply mean that the leaves are reaching the end of their life.

When do the leaves fall? Well, it depends:

  • Annual plants: they lose them when they are about to dry, after flowering.
  • Biannual plants: the second year, after flowering.
  • Perennial or perennial plants: throughout the year.
  • Deciduous plants: they all drop at some time of the year, coinciding with the least favorable time for growth (it can be summer or autumn / winter).

Tips to prevent leaves from turning black

Plants usually have green leaves

To finish, I am going to give you a series of tips so that the leaves stay green, or the color they should be 😉:

Avoid exposing them to direct light if they are not used to it.

It does not matter if you know in advance that it is a sun plant. Before exposing it to the star king, you must get used to it little by little and gradually. Start by putting it 1-2 hours in the sun first thing in the morning, and increase the exposure time in 1 hour or so per week.

Do not wet the plant (and less during the central hours of the day)

We are very used to spraying / spraying the leaves of plants, but that is not quite good. Although the leaves absorb water through the pores on their surface, especially if they are kept indoors or in poorly ventilated areas, that water can suffocate them by staying too long on them.

In addition, when they are sprayed or watered from above, they burn due to the magnifying glass effect, which is a phenomenon that occurs when the sun's rays penetrate, in this case into the water, causing the leaves to burn.

Use clean and sanitized tools

You can't see the fungi, bacteria, and viruses, but that doesn't mean they aren't there. Any small cut can serve as an entrance to the interior of the plants, thus putting them in danger. Therefore, do not hesitate to clean the tools thoroughly, before use at least, but it is also advisable to do it later.

To clean them, hot water and soap are used, or some disinfectant product.

Put healing paste on pruning wounds

When drastic pruning is done, or semi-woody and woody branches are cut, it is highly advisable to seal the wound with healing pasya. Is will prevent the entry of microorganisms, at the same time that it will help the plant to recover from pruning.

So now you know: protect your plant from the star king if it is not used to it, and water it underneath only when necessary. You have more information on this topic here.

I hope it has been useful to you 🙂.


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  1.   Charles of the Castle said

    Hello, I have a 2-year-old white lapacho, it is 2.5 m tall and has more black leaves. I did several treatments with pesticides and I cannot fight them. Could you help me.

    1.    Monica Sanchez said

      Hi carlos.
      I recommend treating it with a systemic fungicide, following the instructions specified on the package.
      A greeting.

  2.   Carlos Martinez-Negrete said

    Hi Monica, I have lemons, guava and limes with the hellos filled with a black coating, what should I do?

    1.    Monica Sanchez said

      Hi carlos.
      Treat them with fungicide, which is an anti-fungal product.
      A greeting.

    2.    Miriam said

      Hello, they gave me some succulent segments, they have the shape of roses, and when I go to plant them I find some black spots, how can I get them out.

      1.    Monica Sanchez said

        Hello Miriam.

        If those spots are small and are on the stem, you can remove them with a knife, as if you were peeling it.
        If they are in the leaves, it is better to leave them. But if they are the ones that are lower, the old ones, they can be removed.

        Regards!

  3.   Maura said

    I have some habanero chili plants but I don't know how to remove the black from all the leaves

    1.    Monica Sanchez said

      Hi Maura.
      Those black spots that you say are caused by a fungus, surely the bold or also called sooty mold. It is often associated with aphids or mealybugs, so I would recommend examining the plants for these insects.

      Since these plants are rather small, you can remove them by hand or with a brush and pharmacy alcohol.

      For the fungus, use organic fungicides in spray, which are sold in nurseries. Or cinnamon if you want something more natural.

      A greeting.

    2.    Merche said

      Hello thanks for your advice ...
      I have a rose bush with rust ... I am treating it with organic fungicides and it seems that new shoots are coming out but soon the new works wrinkle and it looks sick again ... now I am treating it with chemical fungicides but I don't have much hope ... I have it in a covered but open place and does not get the sun
      Might you help me

  4.   Sergio said

    Hello, how is cinnamon applied to the habanero pepper plant?

    1.    Monica Sanchez said

      Hello Sergio.
      You can apply it as if you were adding salt to the salad 🙂 To make it stick better and for a longer time, spray / spray the plant with water, and then pour the cinnamon over it, making sure there are no piles.
      Greetings.

    2.    RODOLFO DAVID CASCON said

      Hello Friends, I have a Kiri or pawlonia that is about 6 months old. I bought it at the nursery, the contours of the leaves turn black and it closes until the leaf is complete and then it falls dry I do not understand what it can be.

      1.    Monica Sanchez said

        Hi Rodolfo.
        Kiri is a tree that wants a lot of water, and a sunny exposure.

        How often do you water it? If the climate is warm and rather dry, it is advisable to water 3-4 times a week in summer, and 1-2 / week the rest of the year.

        En this article you have more information about him.

        Greetings.