You are probably here because you are growing dragon fruit plants and you may have a diseased plant that you are trying to understand what’s causing the disease and how to treat and fix the problem. After partnering in a dragon Fruit farm and growing these plants, I can assure you there are a number of different diseases that can afflict your plants, and dragon Fruit Stem Rot is one of them. So, let’s take a look at what Dragon Fruit Stem rot is and how you can treat the disease.
Dragon Fruit Stem Rot is caused by either a bacterium or a fungus infection of the dragon fruit plant. Depending on the cause of the rot, whether it is a bacteria or fungus, it can appear as yellowing and rotting of the stem and blades, caused by the Xanthomonas campestris and Erwinia carotovora bacteria, or the Colletotrichum gloeosporioides fungi (Anthracnose) which appears as Reddish-brown lesions with the lesion centres becoming white. Treatment is often a copper fungicide, mancozeb and metalaxyl sprays. Spraying one of each chemical at weekly intervals. and pruning out the infected parts of the plant.
As you can see by the pictures above, the Dragon Fruit Stem rot can cause the plant to look unsightly and very unhealthy.
Effective treatment is always going to depend on accurately identifying the cause of the rot, as treatments for fungus infection differ from treatments for bacterial infection.
We will discuss our 3 effective treatments at the end of the article one by one, after explaining the causes of the Dragon Fruit Stem Rot, so you can accurately identify what your infection may be, in simple terms, so please read on.
Its important to note that when root rot is present plants:
- Have poor tolerance to drought
- Sunburn more readily
- Stop growing
- Fruit are smaller
- Susceptible to other diseases
The fungus problem seems to be more prevalent in tropical countries due to the right circumstances which include humidity, moistness and heat.
The fungi spores may already be on a healthy plant but much like a human’s immune system, if the plant is healthy, strong and well-nourished, its own ‘immune system’ will keep the fungi at bay.
Or the fungi spores may be transmitted to a healthy plant by transmission via infected pruning tools or insects that may carry the spores.
If a plant is ‘weak’ and exposed to the fungus, its defences are not going to be strong enough to fight the infection. However, in saying that, even a comparably ‘weak’ plant that is not exposed to any fungus or bacteria is going to look healthy. So, the best practice is to prevent any source of infection in the first place.
Prevention is much easier and better than a cure, but at the same time, you will want to make sure your plants are ‘strong’, well-nourished and healthy.
We will discuss more on how to achieve this at the end of the article.
So now lets look more in-depth at the possible causes of your Dragon Friut Stem rot
Dragon Fruit Stem Turning Yellow or Yellowing
This may be caused by too much sun or sunburn, but likely this would be evident if your leaves also were yellowing and not just the stem. Here is a picture of what dragon fruit yellowing looks like due to too much sun.
The likely cause of the Dragon fruit Stem yellowing and rotting (this can also appear on the blades too) is the Xanthomonas campestris and Erwinia carotovora bacteria. Its interesting to note that a Calcium deficiency has been shown to make this problem worse.
It seems that plants that are deficient in calcium and nitrogen are most susceptible to severe infection such as soft stem rot.
The soft stem rot caused by the bacteria Erwinia carotovora (E. carotovora are similar to the main group of enterobacteria) can start from injured areas and spread. Injury may occur through a sunburn or through a diseased spot caused by a fungi Anthracnose (Colletotrichum). So the original cause may be too much direct sun, especially on a younger plant or a fungus infection that has lead to injury allowing for the bacteria infection.
Dragon Fruit Brown Stem Spot Disease
This is caused by the Fungi Botryosphaeria dothidea and the symptoms are small specks that may be yellow and can enlarge to 5cm in diameter.
Dragon Fruit Stem Turning White
This is caused by the fungi known as Colletotrichum gloeosporioides. The disease symptoms caused by Colletotrichum species are commonly known as anthracnose. As you can see in the pictures above anthracnose looks like Reddish-brown lesions with yellow or white circles on the edges of vine ribs. Lesion centres can become white and may come together to form one large mass to rot much of the vine column.
Its interesting to note that even if the outer part of the stem or branch rots away as long as the main or central cylinder is in tact it can still support and the vine ( As can be seen in the picture below)
However, fruit production may be affected. This is why you can see healthy leaves still at the top of the plant while the bottom looks unsightly and damaged.
However as mentioned although the leaves at the top look ok, fruit production may well be compromised, leading to smaller fruits.
Dragon Fruit Stem Rot Treatment
If you have identified your cause by reading the information above you may now proceed to the right treatment.
You might like to note that if your plant is experiencing sunburn then this could be a symptom that roots of the dragon fruit plant might not be healthy, and that the sunburnt area may cause an entry point for other fungal pathogens to enter the plant.
So lets look at the treatments
1. Treatment of Soft Rot In Dragon Fruit Plant
If you identified your problem above as soft rot caused by bacteria then effective control includes pruning out dying stems.
Its important to sterilize all of your tools prior to and after each cut, so that you don’t spread the disease.
Sterilization methods can include soaking in an alcohol solution, 10% bleach solution or heating the blades with a flame to kill any pathogens that may be present on the surface.
Spraying the affected areas with copper sulfate or any form of copper fungicide will help the plant in the early stages of infection.
Copper fungicides will not cure an infected plant but rather protect it from developing the disease, so it’s important to use the fungicides early on when you first detect this disease or better still whitewashing before the onset of the problem.
Whitewashing is where you paint the susceptible areas with a solution of lime, antifungal agent and anti pest agent and fixing agent such as natural clay to prevent the disease from developing in the first place.
You will also need to systematically improve the health of your plants by ensuring the soil has good drainage.
Do not use chemical weed killers around the base of your plants as it can change the bacterial diversity and balance of the soil leading to the increase of ‘bad bacteria’ vs ‘good bacteria, affecting the health of your plant.
Ensure the Dragon fruit plants have enough nutrition such as magnesium, potassium and phosphorous with a little calcium.
Prevent sun damage by ensuring that plants and especially young plants are protected from the direct sunlight by providing a shade cloth or natural shade.
As the plant gets older and stronger this may be less of an issue, and sunlight will be important for good quality fruit production.
Treatment of Botryosphaeria Disease
For this treatment you will need to prune off the dead limbs and be sure to dispose of them well away from the plantings. Remember to use good sterilization practices of your tools while doing any such pruning.
Try to maintain a very thick layer of mulch to hasten decomposition of fungi on the ground.
Always use good sanitation by sterilizing your tools and good watering practices by irrigating in the morning so that plant surfaces can dry quickly to minimize disease.
As the weather changes from cool to warm, you will need to modify your watering program and pay special attention to watering needs during hot weather. Even though it’s a cactus they still require watering.
2. Treatment of Anthracnose In Dragon Fruit Plant
You will need to prudently remove any diseased
Remove diseased stems by cutting them off ensuring you remove all of the diseased parts. Seal the wound with Cinnamon powder to prevent any new infection from getting into the plant.
Ensure you clean your pruning tools with a 10% bleach solution or use a torch to heat the cutting blades. Be careful you don’t burn the plant with the hot blade, let it cool a little before using on the stems.
If you have high rainfall and misty wet conditions, then try to apply some copper hydroxide before the wet conditions.
Copper will help to reduce new infections, but will not “cure” any existing infections.
We had some success using copper, mancozeb and metalaxyl sprays. Sprayed one of each chemical at weekly intervals.
Again, you will need to systematically improve the natural defences and health of your plants through good nutrition, soil quality, good growing conditions such as drainage and appropriate shade, and cultural management.
This includes limiting the plants’ canopy wetness by watering in the morning so that the plant surfaces are able to dry quickly throughout the day.
Maintain areas around the plants that are weed free, do not use chemical weed killers.
Remove and discard any diseased plants or parts of the plant (i.e. fruits, stems and flowers) promptly when any disease symptoms appear.
*References: University Of California
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