“Why are my plants leaves turning black” is a question that no grower likes to ask themselves because this condition can even lead to plant death.
The reasons that make leaves black are diseases, environmental stresses, nutrient deficiency, and insect attacks.
If you want to know about these causes and how to fix this problem, stay till the end.
- Why Do Plant Leaves Turn Black?
- How Do You Treat Black Leaves on Plants?
Why Do Plant Leaves Turn Black?
Plant leaves turn black when they face fungal or bacterial disease damage. In addition, nutrient deficiency, over-fertilization, and environmental stresses can cause leaves to discolor. Furthermore, insect attacks can also cause leaves to become black in some cases.
– Fungal and Bacterial Disease Attack
The main reason that causes leaves to turn black is fungal and bacterial disease infections. Let’s start with fungus disease first. Root rot is a common plant disease that causes a black appearance. In this disease, roots begin rotting, which decreases their efficiency in absorbing moisture and nutrients.
The damage then spread upwards toward the stem. That is why you will notice the plant turning black at the base after a while. When the disease gets severe, the whole plant will wilt, and the blackness will also be visible on the leaves.
Black leaf is another fungal disease that causes black spots on leaves. It usually occurs in damp conditions as fungi love to grow in such environments. In initial diseases, the spots are tiny. With time, they spread, and the whole leaf can get black.
When it comes to bacterial diseases, the common one that causes leaves to become black is Bacterial Leaf Spot. It is caused by Xanthomonas campestris bacteria that mainly damage leaves. Plants affected by this disease have brown to black spots and can wilt after some time.
– Phosphorus Deficiency
When you see plants turning black and dying, chances are they are deficient in Phosphorus. Plants need a critical nutrient to perform smooth Photosynthesis – a process in which leaves convert light into chemical energy.
So, when plants lack phosphorus, photosynthesis won’t happen as usual. This causes energy deficiency in them, and the effect will be visible on the leaves. The leaves will discolor and can turn brown. After some time, the browning can change into black color.
In addition, phosphorus is crucial for root development. So, the root system will weaken when the soil does not have this nutrient. This will impact the mineral and moisture uptake, making the plants fragile. The leaves can also turn black because of water and nutrient stress in this condition.
– Adding More Fertilizers Than Required
If you are not careful with how many fertilizer doses you apply, problems can also occur. The reason is that over-fertilization makes the soil more toxic, which can burn the root hairs.
When this happens, the moisture and mineral uptake will be affected, which will cause a decline in physiological functions. As a result, leaves won’t stay in their original color and start to get blackened with time.
In addition, adding more fertilizers during a hot day is a bad idea. It is because processes like transpiration are more in high temperatures. So, the mineral uptake will speed up when you add nutrients to the soil in this weather. This will cause fertilizer burn in plants, which leads to leaves becoming black.
– Watering Is Done Incorrectly
When you see plant leaves turning black at tips, you are not watering them right. Generally, it is the overwatering that causes leaves to become black. When you add too much water, the roots find breathing hard.
The oxygen supply gets restricted in this situation, causing the whole plant to face the burden. Moist soil can also promote fungi growth, and diseases like root rot can occur.
In addition, underwatering can also cause problems like leaves turning yellow or having black spots. It is because there is no way for plants to successfully perform physiological functions like photosynthesis, transpiration, etc., without water.
So, underwatering causes these processes to slow down or completely stop, making it hard for leaves to stay green. After a while, the leaves will become black and wilt.
– Environmental Stress
Are your outdoor plant leaves turning black and curling? It means they are facing heat or light stress. The damage is more when you place your plants under direct sunlight. First, they will have big black patches. The whole leaf can become darker when you don’t change its location or provide shade.
The reason that causes sunlight to change leaf color is high-intensity UV rays. These rays kill the plant cells, and others also start apoptosis (programmed cell death) to protect other cells.
Furthermore, there is another way leaves turn black in this situation. When the light intensity is high, leaves speed up evaporation as a cooling effect. This leads to moisture shortage in them, which will initially cause leaves to curl up. After a while, discoloration will happen, and leaves will become black.
Moreover, when you see leaves turning black on indoor plants, you have stressed them by placing them near LED lights. It is recommended to keep at least two feet distance from the lighting source indoors for leaves to stay healthy.
Another environmental factor that causes leaves to become black is extreme humidity levels. This is because when the humidity gets high, plants won’t be able to carry out the process of evaporation. This will cause stress similar to overwatering, and leaves can become black. In addition, the chances of fungal diseases are more when the humidity is high. So, humidity can both directly and indirectly lead to leaf blackening.
– Insect infestations
A pest infestation can also turn leaves black. How? Well, insects love to suck the sap on the leaves – most of them secrete sooty mold or honeydew on the black leaves. Therefore, leaves with sooty mold appear dark.
The insects that produce sooty mold are aphids, whiteflies, mealybugs, spider mites, scales, etc. So, when you see lots of insects near your pants and the leaves are black, it means they are the reason behind this problem.
How Do You Treat Black Leaves on Plants?
To treat plants with black leaves, you should add nutrients and water to the soil to pace up physiological processes. These will make sure leaves stay green and healthy. In addition, treating diseases and getting rid of insect infestation is also crucial to fixing black leaves.
– Fertilize Sensibly
You should ensure the soil has adequate fertilizers to keep the leaves green. Applying organic fertilizers like Compost and bone meal is best to avoid deficiency and over-fertilizations.
Also, you should apply nutrients early in the morning. The day should not be hot either to avoid fertilizer burn. If you choose chemical fertilizers, then make sure you follow dosage instructions to avoid further problems.
– Deal With Diseases
You should apply appropriate fungicides and bactericides when you witness leaves turning brown and black due to diseases. Keeping the moisture level in check is also important if you don’t want the disease to spread.
To ensure you don’t over-water, first check the soil. If it has moisture, then skip the irrigation on that day. When the soil completely dries up, only then apply water. This will help the plant leaves stay in their original colors.
In addition, pruning off infected plant parts is also critical to control diseases. Furthermore, it is advised to use clean tools, as using infected ones can spread fungi and bacteria. You should follow these plant care measures to deal with diseases successfully.
– Plan for Environmental Stressors
If the leaves ever become black, ensure they are not facing any environmental stress. The common one that causes leaf blackening is heat stress. To protect plants from it, you should relocate them to those areas where they will receive indirect light for around six hours only. If relocating is not possible, then use any cover to provide shade. Furthermore, you can also spray cold water on leaves to control the impact of heat.
Moreover, not getting enough light is also a problem. When the problem is light stress, place the pots in those locations where they will get optimal indirect light for at least four hours. If you are an indoor gardener, use LED lights to provide proper lighting conditions.
When there is humidity stress, it is better to prune off extra shoots and leaves to improve air circulation. It would be best if you also opened windows or used a fan to increase the air passage or flow. Also, there should be some space between the two pots. This will lessen the impact of high humidity levels, keeping the leaves green.
– Get Help From Insecticides
It would be best if you took measures to keep your plants safe from insects. If you see lots of these unwanted pests in your garden, use organic repellents like Diatomaceous Earth, Baking soda, Wood ash, Neem oil, etc. You can also get help from beneficial insects, like green lacewings, ladybird beetles, etc., that love eating bad ones.
If you still see insects after trying organic ways, try chemical insecticides. They will work, but the problem with them is that they are costly, and you will have to protect yourself from fumes. For protection, you can wear gloves, goggles, and a mask. Applying insecticides will control the insect population, and leaves won’t become black anymore.
So, that’s all about what causes black leaves of plants and what you can do to fix the problem. Here are the main points of the whole guide to review every key piece of information:
- Never add water and fertilizers more than the plant’s requirement, or the leaves will get black.
- Try to fix plants’ environmental stress to keep them healthy and green.
- In case of a fungus or bacteria attack, apply appropriate fungicides or bactericides and keep the garden clean.
- Apply organic and chemical insecticides to eliminate insect infestation, keeping leaves free from black sooty mold.
That’s all about leaf blackening and how to deal with it easily!
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