You don’t want to see your bamboo plant in black. There can be black spots on foliage, entire leaves turning black, or the whole bamboo turning black.
No matter where it grows, a blackening stalk of bamboo is a warning sign of impending trouble or physiological strain. But don’t panic; fixing most underlying causes is a snap.
The most common cause of blackening bamboo is an infestation of black sooty mold. Wipe away the black mold with a bleach solution and spray insecticidal soap or neem oil regularly to ward off pests. In addition, overfertilization, poor tap water, and fungal spots on the bamboo can contribute to this problem.
Contents
Why is My Bamboo Turning Black?
[1] Sooty Mold is Causing Your Bamboo to Turn Black
It is most likely that sooty mold is causing your bamboo to turn black over time. It’s a relatively harmless moldy growth caused by bamboo-infesting tiny sap-sucking insects. Among the most common are:
- Aphids
- Bamboo mealybugs
- Scale insects
- Whiteflies (these are rare)
Sugary honeydew is excreted by these insects as they feed on the sap of the leaves. The black sooty mold fungus will thrive on this syrup as a food source.
The sooty mold will first appear as black spots. Afterward, a thick gray or black coating layer will quickly spread over the plant’s entire leaves, stems, or bamboo.
If your bamboo has a severe infestation, the mold may prevent it from receiving sunlight, reducing its ability to photosynthesize.
Ants can also be seen farming honeydew along with the black sooty mold. Leaves that have been heavily affected may turn yellow, pale out, and become stunted.
Treatment and Management of Sooty Mold on Bamboo
The first step is simply wiping the black sooty mold off your bamboo. Next, you can use a wet cloth or hose down your plant. Don’t worry; the mold doesn’t infect the inner tissue of your bamboo.
Snip off infected areas – If your bamboo is well-vegetated, you can prune out the heavily moldy parts.
Curb the insect infestation – Unfortunately, the sooty mold will keep reappearing as long as the pest infestation is active. Your best bet is to control the pest through:
- Insecticidal spray
- Neem oil spray – Best repeatedly applied every 7 to 10 days until the bugs are no more.
- Knocking them off with a powerful water jet
- Dubbing with rubbing alcohol
- Frequent application of broad-spectrum insecticides (Check the latest price on Amazon here)
- Encourage natural enemies of the sap-sucking insects, such as parasitic wasps, lady beetles, lacewings, and parasitic mites.
[2] Fungal Spots
A fungal infection, such as rust or anthracnose, or Botrytis, can affect lower and older bamboo leaves and stems, especially in wet or humid conditions.
As a result, your bamboo will eventually turn black and develop spots, dots, or fuzz in various shades of gray, brown, or black.
As a result of their frequent placement in poorly draining growing media or in stuffy, dark spots, bamboo houseplants are particularly prone to fungal spots.
However, the vast majority of these dark spots are circular and do not pose a significant threat to your bamboo.
Treatment and Control of Fungal Spots in Bamboo
For the most part, fungi only appear on bamboo that has already been compromised by disease or old age. Therefore, to make room for more vigorous, younger bamboo, it’s best to isolate these bamboos and perhaps cull them out.
Avoid overwatering your bamboo plant to avoid fungal spots. Also, it’s best to avoid wetting the leaves when you’re watering.
Remove diseased/infected parts and dispose of them properly.
Spray your bamboo using a copper-based fungicide (Check the latest price on Amazon here)
[3] Chlorides and Fluorides in Tap Water May Cause Bamboo to Turn Black
One of the most common mistakes newbie gardeners make is watering their bamboo straight from the faucet. This is because fluorides, chlorides, and other treatment chemicals can build up in the growing medium when using city water.
Ask your water and sewage company for a water quality report if you have any reason to believe this is the case.
Your bamboo will turn black if too much salt is accumulated in the soil. This causes root scorch, leaf damage, and ugly burns. The accumulation of salt may also impair your plant’s ability to absorb nutrients and water.
It will appear scorched, wilted, and blackened if the bamboo’s essential resources are missing. Adding too much salt to the soil is like giving your bamboo a dose of poison. Lucky bamboo, which is highly sensitive to chlorine, will not be pleased. (Source: North Carolina State University)
The leaf margins, leaf tips, or full foliage may also begin to wither and turn black. Furthermore, you may notice some scabs on the soil’s surface, indicating salt over-absorption.
Solution
- Remove salt scabs from the surface of your bamboo growing medium
- The next step is to water your plant heavily to flush out the excessive chlorines, fluorides, and other salt deposits from the potting mix
- For extreme salt buildup, your only option is repotting your bamboo with a fresh batch of rich, well-drained, growing medium
- Next time use distilled water, rainwater, or invest in a water filtration system
[4] Bamboo Rot Diseases Causing It to Turn Black
Another major cause of the plant turning black is bamboo rot. However, in most cases, heart rot or root rot is the most common form.
Bamboo heart rot is a fungal rot disease that affects the stems of the bamboo. The fungus that causes heart rot usually lives inside the stems. It can also spread to the nodes, the inside and outside the stems.
Soggy soil can lead to root rot, which occurs when your bamboo sits in it. There’s also the possibility that contaminated irrigation water is to blame.
Mushrooms can begin to grow alongside the root rot in either type of bamboo rot. So, if your bamboo turns black and has mushrooms growing on it, you have a rot disease to deal with.
Treatment and Control of Bamboo Rot
- You must change the water every three weeks to grow bamboo in water. Use distilled or bottled water instead of city water.
- Allow plenty of indirect sunlight to reach the bamboo, but be careful not to overexpose it to the sun.
- Repot your bamboo after removing any slimy or rotting roots.
[5] Excess Fertilizer is Burning Your Bamboo
Providing your bamboo with the proper nutrients is essential to its long-term viability. Giving your bamboo too much fertilizer, on the other hand, can have the opposite effect.
The reason for this is that excess fertilizer salts will begin to build up in the soil and start to burn both the leaves and roots.
Overfertilization will cause your bamboo to turn black due to salt buildup in the potting mix, similar to what happens with tap water containing chlorine.
Solution
For water-raised lucky bamboos, 2ml liquid fertilizer per month should be sufficient. Liquid fertilizer should be diluted at least half the strength recommended by the manufacturer.
You can also use palm fertilizer or bamboo-specific foliar feeds. Only fertilize once a month to avoid overfeeding. The following table will help you understand bamboo’s nutrient needs.
| Name of Nutrients | Functions | Deficiency | Excess | Application Time |
| Nitrogen | Helps with chlorophyll production | The stems weaken and leaves turn yellow | Becomes vulnerable to pests and diseases | In spring and during the growth period |
| Iron | Photosynthesis and metabolism | This leads to leaf discoloration | Leaves fall off | Once a week |
| Potassium | Strengthen immunity | Plant defenses weaken, leaves turn yellow | Plant growth slows down | During new bud formation |
| Calcium | Promotes cell metabolism | This leads to the death of young shoots | This leads to the death of young shoots | Once a month |
| Magnesium | Strengthen immunity | Plant defenses weaken and leaves turn yellow | Roots weaken | A feed with Epsom Salt |
| Iron | Helps with photosynthesis and metabolic activity | This leads to discoloration of the leaf | Leaves fall | Once every two weeks with Chelated Liquid Iron |
| Molybdenum | Helps to process potassium, phosphorus, and nitrogen | Poor growth | Interferes with the absorption of copper, the leaf curls | Once every 2 months |
| Manganese | Knocks out toxic materials | Becomes vulnerable to diseases | This leads to the yellowing of bamboo | Once every 2 weeks |
| Fluorine | A defender against pathogens | Plant stop growing | The Lower leaves turn brown | Once a month |