As beautiful and easy to care for orchids as with all other plants, diseases or pests can occur that require proper control. Since the orchids are usually on the windowsill or in another protected place, they are rarely attacked. However, it is not uncommon for diseases to be introduced when plants are purchased, which can then be transmitted to other plants and orchids. If you are currently having problems with your orchids and suspect orchid diseases, then we hope that our list can help you.
Tips for healthy plants
We have put together some common signs on leaves, as well as typical pests on the pretty orchids, which you can use to combat orchid diseases. These tips can also be helpful for other types of plants. The pests in particular are not only common for orchids, but also occur on other specimens.
Wrinkled leaves
This common problem is typical of Oncidium, Miltonia, Cambria, Odontoglossum and Promenea, species that are more complicated to care for. The newly growing leaf of the plant appears in a crumpled form and is reminiscent of an accordion. If you have also noticed such a problem, you will certainly be interested to know what the reason for these orchid diseases is.
Orchids and diseases
These orchids, like all other plants, have certain environmental and care requirements. Sufficient light, water and appropriate humidity are important to avoid orchid diseases. If these are not provided, the plants will stop growing. If the plant feels comfortable again, it will continue to grow. However, this creates these wrinkles. The bad news is that these wrinkles cannot be corrected afterwards. The leaves don't look very pretty among the normal leaves, but fortunately they don't harm the plant. You can only prevent future concertina growth by providing species-appropriate care.
With the Phalaenopsis variety, owners often panic when leaves begin to turn yellow and fall off after a while. But this does not necessarily have to be related to orchid diseases. If the lower leaves fall off, this is usually a normal process. The falling off of older leaves is a normal aging process that usually takes place in the cooler seasons and does not harm the plants in any way.
Poor conditions
Nevertheless, you should consider the other options and check whether the conditions could not be inadequate. On the one hand, the reason for leaf loss can also be a lack of light. However, in this case, several or even all of the leaves turn yellow. Now you should act quickly because the weakened plant is now more susceptible to diseases. Place them in a bright place but out of direct sunlight.
Possible causes of illness
If there is nothing wrong with the location of your plant, there are two other possible reasons for the yellow leaves. On the one hand, it could be a pest infestation as orchid diseases (we have listed some pests below) and on the other hand, a new substrate may be necessary. This should be replaced every two years. Over time it breaks down, becomes dense and the roots, which require a lot of air, rot. This can be recognized again by the yellow leaves.
Brown or black spots
Here too, there are various possible causes for this. Sometimes the problem cannot be solved, which unfortunately can mean that the diseased plant has to be disposed of so as not to infect other specimens. But let's not paint the devil on the wall. First, take a closer look at the stains to determine the possible cause.
Sunburn – Common problem in summer
As you already know, the direct sun is not good for the orchid. The plant fares particularly badly in a south-facing window if there is no guaranteed sun protection. Sunburn causes brown spots that slowly turn black and, if exposed to the sun for a long time, can even turn white in the middle. You will also notice that it is a sunburn because the spots are not getting bigger or spreading and are dry. Now act quickly, because in an early stage (if the spots are still yellowish) they can even disappear again. Relocate the plant so that the weakened plant does not attract further orchid diseases. If you only have space in a sunny place, provide sun protection. Curtains, blinds that are not completely closed or even a larger, sun-loving plant are well suited for this.
fungal infections
However, the spots here are also brown, but they are not dry and are spreading slowly. The surface is uneven and sunken in some places. Fungi develop when there is too much moisture. One reason is spraying the leaves with water too often. The so-called black spot disease (Phomopsis viticola) is contagious, so you should isolate the affected plant. Then cut off the affected areas. Use a sharp knife that must be disinfected beforehand and after each use. The same goes for your hands. Otherwise, you risk infecting other plants. In addition, you can use a suitable remedy. But that alone is often not enough, because fungi are stubborn things. Also, reduce the humidity. For this purpose you can ventilate. But avoid drafts1
bacteria
Bacterial infections are just as stubborn and highly contagious. Isolation of the sick plant is therefore mandatory! With bacteria, the leaves don't just turn yellow. These orchid diseases produce brown spots that are slightly sunken into the leaf and have a sharply defined edge. In addition, there is often a damp surface on the leaves and mold. With such orchid diseases, disposal is usually the better decision because healing is very difficult. However, if you don't want to give up on your orchid so quickly, proceed as you would with fungal infestation. Cut off diseased areas and don't forget to disinfect them adequately. This also applies to the location of the plant. Use, for example, hydrogen peroxide. It is equally important that you change the substrate and the pot.
Rotting orchids - stem rot
The so-called stem rot is also one of the typical diseases. As the name suggests, it starts at the trunk and spreads to the leaves. This rot is caused by incorrect watering and by bacteria in the irrigation water. It is important to note that the leaf axils, i.e. the area where the leaves grow from the stem, must not be watered. The water remains there and cannot evaporate quickly enough, especially when the humidity is high. This leads to the trunk rotting. The same applies to excess water in the planter, which in turn affects the roots and leaves, which turn brown in the axis area and fall off after a while.
Water correctly
Therefore, water correctly and be sure to avoid excess water accumulating. If only a few roots are affected, the orchid can still be saved from these orchid diseases. Use disinfected scissors to simply cut off the rotten roots. After that, the orchid needs to be kept drier to get rid of excess moisture. However, if all the roots or even the trunk are rotten, saving the plant is rather impossible.
Herzfäule
As mentioned, the starting point for rot as an orchid disease can also be in the area of the leaf axils. You can save the plant as long as the bulb is not affected. In this case, cut off the leaves. The interface is then best disinfected with a charcoal powder. Cinnamon is also often used. Afterwards, water more sparingly and, above all, only by dipping so that water does not get back into the armpits and diseases do not develop in the orchids.
These problems are quite common and can have various causes. The first logical cause is too infrequent watering. If the orchid dries out quickly, this leads to the buds being dropped, but the flowers are also often affected. To avoid this problem, it is important that you maintain a regular watering schedule. The best way to control this is to stick to a specific day of the week. In summer, weekly watering is necessary; in winter, watering every two weeks is sufficient. The best way to control your rhythm is to choose a specific day and always stick to it. It is also helpful to look into the transparent pot. Water droplets inside, as well as green roots, indicate that there is sufficient moisture. If the roots are silvery, you can water.
A change of location
When you buy a new orchid, this is usually the cause and not specific diseases. In your house, all the conditions are different than at the florist or hardware store. This change stresses the plant, causing it to simply drop its buds. This shouldn't scare you at all. Because at the base of the former buds can form with proper care. If necessary, you just need to be patient until the new flower stalk grows.
Drafts
Some problems are caused by drafts. This doesn't suit us humans very well either, how could it be different for plants. But don't let that put you off. Drafts aren't just caused by windows being left open for too long. Drafts can also occur in winter when the window is closed, especially if the orchid is on the window sill and above a radiator. The warm air rising upwards then creates a draft. The higher the ceiling, the greater the draft caused by heating air.
Dark location and direct sun
Although the flowers do not like direct sun, they do require a lot of light. A north-facing window is perfect in summer, but is not sufficient in the other seasons. This darker period of the year predisposes the plant to itsto shed flowers. Therefore, look for another permanent location or move the plant in good time. An east window or a location in the south or west with sun protection is perfect. Sun protection is particularly important to avoid illness, because it's not just the leaves that can burn. The flowers may also drop.
Pests on orchids
You are probably wondering how orchid diseases can occur when the pests are actually visible. That's not entirely true. Many of the pests cleverly hide under the leaves or in the substrate and are only discovered when they have already caused damage to the plant. Checking the plant regularly is the best precaution. If you have already discovered a change in the plant that cannot be attributed to the causes mentioned above, you are probably dealing with one of the following pests. Isolate the affected plant to protect others and also check the remaining specimens as a precaution. They could already be infected.
Wool lice
Mealybugs are one of those pests that hide under the leaves and cause problems. They are also known as mealybugs. They can also be found in the leaf axils, building isolated nests. They damage the plant by sucking out its sap. You can recognize them visually because they are fluffy. They can be compared to cotton swabs. While they suck the sap, they also secrete substances that damage the plant. This includes fructose, which is preferred by fungi. In the wild, beneficial insects such as ants or ladybirds help against infestation. However, being a houseplant requires help from you. Soak cotton swabs in alcohol and remove individual nests. Chemical agents rarely help because the mealybugs have a protective shell. A regular inspection is then necessary.
Fight scale insects
The scale insect is very similar to mealybugs. They are protected from chemicals by their shell and suck out the plant's juices again. This is an advantage if you use a product that is first absorbed by the plant and then by the lice. However, this is a lengthy process. You will be more successful in combating these pests if you use elephant or tea tree oil. You collect the oil with a cotton swab and then drip it onto the lice. The animals are isolated and no longer receive oxygen, whereupon they suffocate. This also means that action is taken against the brood at the same time. Simply scratching off the lice should be avoided. In doing so, you risk damaging the plant as well.
Aphids
The hated aphids are rarely the cause of orchid diseases. If you have discovered some on your plants, then it is probably on the young leaves, the flower stalks or the flowers themselves. There they suck out the juice again and, like the mealybugs, secrete fructose. Since you can't use the ants to help you, use chrysanthemum extract instead. It does not harm the plant, but works successfully against annoying lice. After treatment, check regularly for additional lice.
Thrips in orchids
They receive the perfect living conditionsThrips as pathogensfor orchids diseases caused by dry air. This is usually the case when it is located above the heater. The winged and 1 mm large pests can usually be found under the leaves, where they pierce the cells and then suck the juice. The leaves turn yellow and eventually fall off. Insecticides are very helpful for these animals. Alternatively, you can also prepare a solution of oil, dish soap and water. Simply mix 2 tablespoons of oil and a little dishwashing liquid with a liter of water in a spray bottle and spray your plant. Repeat this several times until you get rid of the animals.
Spider mites
Like thrips, spider mites like dry indoor air. For this reason, increasing pleasure moisture for a few days is very useful. For example, dip your plant and then pack the pot in a plastic bag. The tiny pests (0.3 to 0.5 mm in size) accumulate on the underside of the leaves. The bites of spider mites as a cause of orchid diseases turn the leaves silvery, which again causes yellow leaves that later fall off. Insecticides will not help you here. Helpers from nature are often used in greenhouses. The predatory mites prove to be the perfect fighter. The process in the apartment is done by hand. Wipe the animals with a simple, damp cloth. Alternatively, spray the orchid with a solution of water and neem oil, repeating this several times.
