Orchid diseases

Orchid diseases

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Orchid diseases

The orchids are very delicate, in fact, they can be affected by numerous pathologies, sometimes even fatal, the most common are those that are parasitic but not only, they can also be due to fungi and insects, and this also depends a lot on incorrect cultivation techniques. First of all, care must be taken not to ruin any part in question as the plant will suffer a lot and remove the parts that are rotten or the dry leaves. If injuries are caused during this operation, the part that is damaged with cicatrene or cinnamon powder should be immediately dusted.
If you are in possession of diseased orchids you must separate them from the others, the same thing applies to newly purchased orchids, for which it is always best to keep them in quarantine until you are sure that they are perfectly healthy. Before carrying out any operation, be careful to carefully sterilize the tools you intend to use, especially the scissors and vases that must be washed with disinfectants or varichina at the time of repotting.
Do not spray water for any reason during the hottest hours of the day and do not leave the aerial parts of your wet plants during the night. To water correctly without compromising the health of your plants, it is advisable to immerse the entire pot in water for about 15-20 minutes, after which it is left to drain hanging until all the water has disappeared.
To water it would be better to use rainwater or demineralised water at room temperature, preferable as they do not contain chlorine and calcium carbonate. Orchids are usually grown in round pots with a diameter starting at 20 centimeters up to 40 centimeters.
These plants suffer a lot from the pungent cold, in fact it is advisable to repair them in winter with the sheets of "non-woven fabric" or with dry leaves if no special greenhouses are available. In addition, orchids suffer from water excesses, which is why it is not absolutely necessary to fill the water saucers.

Non-Parasitic Diseases

The causes of non-parasitic diseases can be varied. If the leaves start to fall it can be an excess of water, while if the plant is very hard to grow and the flowers fall it can be due to poor irrigation.
Furthermore, if the leaves are opaque and not shiny, you need to move the plant, as it may be that where it has been stored the climate is not humid enough. If it is difficult to flourish, instead, the cause is the lack of lighting. Finally, if the orchid plant has burnt leaves it has been exposed to too much light when it had wet leaves and this problem can also give rise to the development of micro-organisms such as fungi.
Orchids can be affected by the note and annoying cochineal, which can be either brown or cotton. In this case the leaves appear with brown spots on the surface. Cochineal is difficult and boring to eradicate definitively: if it is in the initial phase it can be tried with cotton soaked in alcohol but if the problem is not solved it is necessary to repot our plants, carefully cleaning the roots and leaves under a jet of water.
Finally, it is useful to proceed with specific pesticide treatments.
The plant can also be affected by aphids, whose symptoms can be seen with the naked eye, as the leaves tend to yellow very quickly and the flowers tend to deform. To combat the aphids, it is necessary to proceed with specific and targeted insecticides for the latter. Also very frequent is the attack of the red spider which makes the leaves crumble on themselves until they inevitably fall.


Cascola flowers Few waterings, temperature changes
Cascola leaves Too much water, rot
Leaves not turgid Little environmental humidity
Dry stains Foliar blanching
Brown or dark spots Cochineal, black rot
Weakening aphids
Yellow leaves, weakening, cobwebs Red spider mite
Soft flowers and leaves Gray mold
Rotten roots fusarium

Mushroom diseases

Fungal diseases are mainly due to poor cultivation or excessive humidity, cold temperatures and excessive irrigation. Black rot is caused by the Phytophthora fungus that affects the leaves causing black spots, this fungus proliferates due to low temperatures and high humidity. If affected by black rot our orchid plants will undergo death within 15-20 days.

Bacterial Diseases

Orchids can be affected by bacterial diseases, sometimes even fatal, as in the case of the very powerful bacterium Xanthomonas campestris Pelargoni, which can also extend to neighboring plants. Once this disease settles in the plant there is nothing to do but completely remove the plant by pulling it out and burning it, if possible away from other plants. It is also very important to eliminate especially the infected soil and the pot.
When the bacterium strikes the plant it starts to yellow very quickly and to subsequently lose the leaves. This disease can be caused mainly by the use of infected tools or vessels and therefore not disinfected.

Physiopathies of orchids

These problems depend on inadequate cultivation conditions. These are the first signs of discomfort and for this reason they should never be underestimated.
One of the most frequent drawbacks is the fall (or abortion) of flowers: this phenomenon is due to sudden cold currents or poor irrigation.
Failure to release new stems may be due to poor light, lack of fertilizer or having missed the rest period with lower temperatures.
The foliar drop is linked to excessive watering and start of root and collar problems (rot). If these, on the other hand, appear to be a little turgid it is likely that both irrigation and environmental humidity are scarce
If we see dry areas appear, a burn is likely: we absolutely avoid the direct sun, especially if concentrated by the glass or possibly by water residues from the nebulisations.
Leaves with a light color and stunted growth can be linked to deficiencies of microelements.

Orchid diseases caused by animal pests

The most frequent insect is the cottony cochineal There is signaled by brown spots on the leaves. They spread easily everywhere, even on the collar and at root level.
To eradicate them it is important to flare the plant, eliminate the compromised roots and replace the bark (carefully sterilizing it). Then thoroughly clean the entire plant by manually removing all the insects and then passing a cotton swab soaked in alcohol.
A treatment with white oil activated by a systemic insecticide is indispensable. The ideal is to distribute the latter through irrigation so that it spreads from the roots to the apexes.
Aphids are another enemy: they weaken the plant by sucking its sap. They are also dangerous vehicles of viruses. You can fight with contact insecticides and ingestion, such as pyrethrins and pyrethroids.
Red spider mite is more difficult to deal with: it manifests itself with leaf bleaching and loss of general vigor. You will also notice dots on the back of the leaf and, in severe cases, small spider webs.
It is important to increase the environmental humidity by often vaporizing the leaves, possibly moving the plant to a more shaded area and using specific products, active on all the stages of development of this mite.


They are closely linked to crop errors in particular excessive watering, water in places not recommended (such as the collar), stagnant air and substrate not suitable or too old.
The most typical condition is black rot: black spots appear on leaves, pseudobulbs and roots: it is linked to too high humidity in conjunction with low temperatures. We avoid these conditions and remember to always use sharp and disinfected instruments when we carry out plant divisions or cleaning.
Another problem is rot on leaves, flowers or roots: it is gray mold. In this case too, the concomitant causes are excessive cold and humidity. We eliminate the compromised parts and use a specific systemic fungicide.
Anthracnose is also frequent due to excessive humidity: we clean the orchid and subject it to a cycle with a specific product given for irrigation.

Bacteria and virosis

Bacteria and viruses in orchids are not very common, but they are very difficult to fight. The former cause necrosis of the leaves or pseudobulbs. The latter are presented with typical fading of the foliage and in the long run they heavily weaken the subjects. The only strategy against bacteriosis and virosis is prevention, always using disinfected instruments and avoiding vector parasites.

Basic tips for orchid care

As we have seen, to avoid these pathologies it is of fundamental importance to know some precautions about the cultivation of orchids.
- We often check the health of our orchids
- Promptly remove all parts with obvious rot by using flame-disinfected or bleached instruments.
- Place the plant in an airy area
- We spray the morning and afternoon, but avoid the evening.
- We avoid water from wetting the collar or pseudobulbs where it would stagnate.
- When we repot, we choose transparent containers (which allow us to monitor the roots) and disinfect them carefully. If possible we create holes on the sides to facilitate the passage of air.
- We choose a specially prepared substrate or sterilize the bark in the oven or boil it for a long time.
- We avoid damaging or cutting the plant: in this case we create a clean cut and disinfect with cinnamon.
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