AgroSemFund
AgroSemFund
Becker RU
Becker RU

Orchid diseases: description and control measures

Like most plants, orchids affected by three types of diseases: fungal, viral and bacterial. It is also not uncommon for these exotic plants to begin to ache due to improper care (creating unsuitable temperature and humidity conditions, excessively abundant watering or placement of vases in drafts). To fight orchid diseases as efficiently as possible, carefully read the recommendations presented on this page.

Fungal diseases of orchids: how and how to treat diseases (with video)

Fungal diseases of orchids, always accompanying tropical plants in culture, cause various pathogenic fungi that are able to release mycotoxins that poison plant tissues in the course of their vital activity. And often the same fungus is able to release not one, but several toxins at once. Symptoms of the disease can also manifest themselves in different ways, they are largely dependent on the type of host plant, its general condition, and the characteristics of cultivation.

Anthracnose. Colletotrichum gloeosporioides (Penz.) Penz. & Sacc. - sexual stage, Glomerella cingulata - asexual stage of the same mushroom.

Not very aggressive orchid disease, often on the leaves than on the stems. Black spots on the leaves or on the tips of the leaves have a yellow edging. Spots gradually grow, and over time, necrosis can spread to the entire leaf.

Control measures. The greatest activity of these fungi is observed at elevated temperature and humidity, combined with low light. Therefore, at the first symptoms of the disease, it is necessary to immediately transfer the plant to a drier, cooler place, to provide better illumination and good ventilation of the room.

The affected areas are removed, cutting off not only necro patches, but still grabbing 1 — 2 cm of living green tissue. If the sheet is severely affected, it should be cut off completely. After each incision, the instrument should be treated with vodka or alcohol, and you can also ignite the cutting surfaces of the pruner over the flame.

When treating this orchid disease, plants should also be disinfected by sesing — sprinkle with crushed activated charcoal or ground cinnamon, anoint with a fungicide paste or alcohol solution. I recommend using this complex of measures for orchids affected by any fungal infections.

In the case of a highly progressive infection, it is necessary to remove the damaged areas and treat the diseased plants with cinebium (0,4%), thiram (3%) or systemic fungicides, adding adhesives (a few drops of detergent).

Root Rot (Fusarium oxysporum Schlecht.j).

This pathogenic fungus parasitizes not only on the roots, but also on other vegetative parts of orchids. This disease of orchid roots appears as a rounded or elongated purple or pink-purple spots on rhizomes and pseudobulbs, which are actively expanding, affecting new areas of storing shoots, buds of renewal, flower buds. Inside the shoots, the infection can penetrate the roots, causing their death.

Symptoms of defeat shoots - large reddish-brown weeping spots, quickly spreading to healthy tissue. The leaves of orchids affected by Fusarium become spotty, turn yellow, thin out and wither.

As can be seen in the photo, with this disease of orchids, the edges of the leaves become a gray metallic shade:

The rot usually appears on flowers that have not yet been opened, which turn yellow at the bud stage and soon fall off. The spread rate of this fungus is so high that it can take only about 20 days from the moment of infection to the complete destruction of the plant. The use of fungicides can prevent the death of plants, but their shoots still remain severely deformed, pseudobulbs skewed and shriveled, and the roots die off completely.

Control measures. First of all, the diseased plant should be isolated from healthy to prevent the spread of infection. Then it is necessary not only to remove all diseased parts of the plants, but also to completely destroy them (for example, to burn them). Of great importance are preventive agrotechnical measures, such as disinfection of pots and drainage.

For transplantation, use only fresh substrate and new drainage. To prevent the spread of infection will also help regular airing. As a chemical control measure against this orchid disease, spraying and watering 0,2% base suspension, benomyl or topsin three times in a row at intervals of 10 is recommended.

Fusarium flowers disease (Fusarium moniliforme Sheld. J.).

On flowers, buds and peduncles, tumbled dark brown and black spots appear, which are covered with dust like whitish mycelium with small pink fruit bodies. On the leaves, this disease manifests itself in the form of small spots, here, as a rule, sporulation is absent. Inside the plant, a pathogenic fungus penetrates through small wounds.

Control measures. This disease of orchid flowers is very rarely manifested in the conditions of proper agricultural technology with good ventilation. But if the pathogen is identified, it is necessary to remove all the affected parts of the plant, lower the temperature, increase the illumination and abandon the spraying of flowers and leaves, because the fusarium can spread with water droplets.

As chemical treatments, it is recommended to carry out the same measures as for combating other types of Fusarium (see Fusarium oxysporum), as well as 3-multiple spraying with zineb (0,4%) every 4 — 7 days.

Core or crown rot (Phytophthora cactorum (Lib. Et Cohn) Schroet.).

Wound parasite that secretes strong toxins. Its mycelium passes inside the tissues of the host plant, both between the cells and through them. The disease begins to appear on young shoots, leaves or roots, gradually capturing new foci.

Pay attention to the photo - with this orchid disease on the leaves, the first symptoms of infection look like small weeping spots randomly located on the outside:

These spots quickly become purplish-brown or black-purple, sometimes with a yellowish rim at the point of contact with healthy leaf tissues. Damaged areas gradually increase and, when pressed, may release fluid.

With age, these lesions turn black and dry, but when touched with healthy parts, plants can also transmit the infection. In addition, the infection can spread to the internal tissues of the plant along the roots and rhizomes. Especially quickly it occurs in wet conditions.

Infection of young shoots is easily identified visually by the purple or purple-brown areas with yellowish edges. Most often, these symptoms appear when the air humidity is high and the water stagnates inside the leaf outlet of the developing shoots.

Pseudobulb and rhizome areas of shoots through roots may be infected. In this case, the pathogen spreads through the internal tissues and visually may look like filing the base of the shoots and leaves.

Sometimes the infection focuses on the shoots, while there are no noticeable signs of infection on the leaves, but they become brittle and quickly fall off. On the flowers, the infection appears as light brown, weeping spots.

Control measures. Among the preventive measures against this orchid disease is proper care with controlled temperature and humidity, which should not be too high.

It is also recommended to remove all parts of the plant with signs of disease and to refrain from spraying shoots and leaves in order to prevent the spread of infection through water droplets. During transplantation, the obligatory condition is the use of clean disinfected containers and drainage, as well as fresh substrates.

After removal of all affected parts, the plants are sprayed with zineb (0,4%), spilled with Bordeaux mixture (1%), copper sulfate (1%) or powdered with thiram.

Black rot of orchids (Pythium ultimum Triw.j).

This pathogenic fungus penetrates the plant through the roots, spreads through the rhizome and infects the psedobulba, and then the leaves. In this case, pseudobulbs shrivel, harden and mummify, and the orchid leaves with this disease become shiny black, soft to the touch. When pressed, liquid flows out of them. In conditions of excessive moisture, leaf rot can occur from the tip.

Black rot kills orchids in bulk and in a short time. Particularly affected by this disease are seedlings and young plants. In seedlings, as a rule, the growth point, located at the base of the shoot, rots first.

Control measures. Pythium successfully develops in cool and humid conditions, so an increase in temperature and a decrease in humidity help prevent the spread of the disease.

Since this infection is transmitted from plant to plant through water sprays, it is necessary to eliminate spraying of the plants and arrange orchids more freely so that their leaves do not touch.

To treat this disease of leaves and roots as efficiently as possible, all diseased plants should be rejected immediately - this is one of the most important protective measures that prevent the spread of black rot.

This applies particularly to seedlings. You can try to treat adult plants by removing all the affected areas and submerging them on 20 — 30 minutes. in a solution of copper-containing drugs - copper oxychloride (0,5%) or copper vitriol (1 — 3%).

In the event that several seedling orchids are planted in the common pot, in the fungicide it is necessary to soak not only the diseased, but also all the other plants.

Leaf rot (Pythium splendens braun.).

The orchid leaves affected by this disease are covered with oval or rounded dark brown spots. These spots have blurred edges, the color of which varies from dark brown to light brown and green, gradually merging with the normal coloring of healthy parts of the sheet. The spots gradually increase in size and, in the end, the leaf dies.

Rhizoctonia (Rhizoctonia solani JG Kuhn).

Although this fungus initially affects the roots, the first symptoms of infection with this disease appear on the leaves, which turn yellow, thin out and deform. Young shoots develop depressed, weak, and if not in time to control the spread of infection, not only seedlings, but also adult plants can quickly die. On the roots, the infection appears as a brown rot with white and brown fungal hyphae on the surface.

Control measures. This disease is quickly transmitted from one plant to another, therefore it is necessary to remove and destroy diseased parts of plants, completely replace the substrate, use sterilized tools and auxiliary materials (pots, drainage).

Often, root rot begins due to an unfavorable environment inside the pot, which is created with regular watering of the substrate, watering with hard water, or with too high a concentration of fertilizers. In this case, it is necessary to transplant the plant into a fresh substrate, ensuring good drainage and optimizing the salt concentration of irrigated solutions.

Among the chemical control measures, we recommend watering plants with systemic fungicides (benomyl (0,2%), foundationol (0,2%)), or spraying with zineb (0,4%), tiram (1 — 3%).

Ways to treat this orchid disease are shown in these photos:

Gray decay (Botrytis cinerea Pers.).

Manifestations of this disease (small gray, black or brown spots on flowers) are mainly associated with a prolonged decrease in temperature at high relative humidity of the air. Often one cold night is enough for the flowers to become completely covered with gray mold.

Control measures. Among preventive measures, it is recommended to refrain from spraying the buds and flowers, as well as to remove faded and diseased flowers in time. In addition, it is recommended to increase the air circulation around the plants, decrease the relative humidity and increase night temperatures.

Infection can be transmitted by greenhouse pests (slugs, snails, insects), so it is recommended to constantly monitor their numbers.

Among the chemical measures to combat this orchid disease, treatment with systemic fungicides is used - benomyl (0,2%), basezol (0,2%).

Leaf tip rot (Botrytis sp.).

The infection appears on the leaves as dark spots, which gradually grow and move to the ends of the leaves. The tips of the leaves are covered with spores. This disease appears more often on orchids watered with hard water or regularly receiving an excess of mineral nutrition. In such plants, the tips of the leaves are weakened and susceptible to infection with Botrytis.

Control measures: As a preventive measure, it is recommended to balance the mineral nutrition and optimize the acidity of irrigation water.

To learn more about the treatment of diseases of orchids, watch this video:

Phyllosticosis (Phyllostictina capitalensis Henn. and etc.).

Spots can appear both on the leaves and on the psvdobulb. Initially, they appear as lighter whitish-green or yellowish spots of oval or rounded shape, which eventually turn brown and black. Spots can be small or larger, in the form of dashes, ovals, rhombuses or stripes. Each individual spot in diameter reaches no more than 6 mm.

If the infection progresses, then black or dark brown sporulation appear in the center of the spots. The disease is transmitted through water droplets, a poorly disinfected instrument, etc. From the moment of infection to the onset of signs of the disease, 3 — 6 weeks have passed.

Control measures. Sick plants should be isolated by removing all affected areas from them. Since phyllossticosis develops rapidly at high humidity and temperature above 25 ° С, this infection can be prevented by a decrease in temperature, good illumination, regular ventilation and adherence to phytosanitary measures.

Among the chemical methods of treating this disease of orchid leaves, spraying with systemic fungicides can be recommended - benomyl (0,2%), foundationol (0,2%) and preparations based on copper - copper chlorine, bordeaux liquid, copper sulphate.

In the next section of the article, you will learn what viral diseases can affect orchids, and how you can fight them.

Orchid viral diseases: photos and how to deal with diseases

Cymbidium Mosaic Virus (CyMMV).

This viral disease is extremely widespread among orchids and is found exclusively in members of this family. In different genera of orchids, its symptoms manifest themselves in different ways. The disease is called black Orchid necrosis, Orchid mosaic virus, Cattleya variegation, and so on.

On phalaenopsis flowers, this virus appears as more pale than the flower color, randomly located on the petals and sepals of spots and streaks. These divorces are especially pronounced on flowers through 1 — 2 weeks after blooming.

On leaves, this disease of domestic orchids begins with the appearance of small or larger, shapeless pale green chlorotic spots, which are then necrotic. Spots can be arranged in the form of parallel black small strokes, rings, concentric circles, straight or curved lines located at an acute angle to the main vein of the leaf, and so on.

When combined with other viruses on the same sheet may appear spots of a different nature. In orchids with thin leaves, the virus on the leaves appears through 3 — 5 weeks after infection, especially on young shoots.

Initially, chlorotic mosaic streaks and spots appear, which then become more clearly defined and darken. Old leaves have necrosis of the affected areas. The intensity of growth and flowering is reduced.

On the leaves of phalaenopsis manifestations of viral infection is very diverse. It can be as light green chlorotic spots, and deeply depressed necrotic, as well as weeping spots. Necrosis often occurs on the lower surface of the leaves. Severely affected leaves die off. Sometimes, however, the external symptoms of a viral infection are completely absent even with a positive test for the presence of a virus.

Effective measures to combat this disease orchid at home does not exist yet, therefore all diseased plants are destroyed.

Orchidic tobacco mosaic virus (TMV-O).

The tobacco mosaic virus (TMV) is often confused with the Orchid Tobacco Mosaic Virus (TMV-O), but the latter has a special nature and, apart from the Orchid Mosaic, it infects only a few indicator plants, while the tobacco mosaic virus infects countless objects.

Most tobacco mosaic virus (TMV) carriers do not infect orchids. The TMV-O virus is often found together with other viruses.

Effective measures to combat viruses do not yet exist, so all diseased plants are destroyed.

Phalaenopsis mosaic virus (CyMV + TMV-O).

This disease is the result of a combination of two viruses - Cymbidium mosaic virus (CyMV) and Orchid Tobacco Mosaic Virus (TMV-O).

Look at the pictures - with this disease, orchid leaves are covered with alternating light green or chlorotic spots:

Leaf tissues are destroyed: on the upper side of the leaf blades become covered with chlorotic and necrotic spots, and on the lower side, wide chlorotic grooves or weeping spots appear, with time the spots become depressed.

Effective measures to combat viruses do not yet exist, so all diseased plants are destroyed.

Trichopilia virus (T1).

This virus was found in Germany in tropical epiphytic orchids of the genus Trichopilia (Trichopilia). Manifested in the form of continuous or dashed light and dark lines, located "fence" and going at an acute angle to the main vein of the sheet. There is no further information about this virus.

The following is a description of bacterial diseases of orchids and tips on how to treat plants.

Bacterial diseases of orchids and measures to combat them

Soft Bacterial Rot (Erwinia carotovora 0ones Holland).

This infection initially manifests itself in the form of small weeping spots, which soon turn brown, rot quickly spreads through the tissues, and the leaves and roots are affected several times faster than rhizomes and pseudobulbs. When pressed on the affected areas, a brown, foul-smelling liquid is released. With the defeat of the core of young growing shoots and nights of the renewal of the plant die, and from the beginning of the development of the disease to the complete destruction of the orchid can pass the entire 2 — 3 day.

Control measures. It is necessary to react to the first manifestations of this disease immediately. First of all, it is necessary to isolate the affected plants and treat the place on the rack that they occupied with an 10% solution of Na hypochlorite or 25% solution of any household detergent containing active oxygen.

In order to prevent the spread of infection through water droplets, it is necessary to eliminate spraying and reduce the relative humidity of the air. In addition, this disease is spread by phytophagi (ticks, insects and mollusks), therefore it is necessary to constantly monitor the presence of pests.

As shown in the photo, when treating this orchid disease from the leaves and other parts of diseased plants, all affected areas should be removed, disinfecting the instrument after each cut:

Then carry out spraying with drugs containing antibiotics (active ingredients myomycin, streptomycin, tetracycline, ampicillin, precursors, phytobacteriomycin). In addition, it is recommended to process the sections with a paste from a systemic fungicide (foundation, benomyl). After treatment, it is necessary to reduce watering and maintain the diseased plant for 2 weeks at low humidity (55 — 60%).

To prevent infection, you can sprinkle diseased plants with some biological fungicide, for example, "Fitosporinom-M" or "Pseudobacterin-2", preparing the working solution by diluting the drug with water 100 times.

Bacterial rot of chrysanthemums (Erwinia chrysanthemi Burkholder et alj).

The disease manifests itself on the leaves. In species with thin soft leaves, along with the rapidly darkening weeping spots, yellowing of the leaf blade is observed. Phalaenopsis with fleshy leathery leaves first appear translucent areas that quickly become black and indented.

Control measures. Home care orchid conditionsaffected by this disease is the same as for Erwinia carotovora.

Bacterial rot of venereal shoes (Erwinia cypripedii (Hori) Bergey, Harrison, Breed & Huntoonj).

At the beginning, small round or oval moist spots appear on the leaves, which eventually increase in size and become dark brown. Most often, these spots begin to develop in the center of the leaf and appear both on the outside and on the inside. They quickly spread through the tissues of young growing shoots, causing their death.

As seen on photo on orchid leaves this disease begins to manifest itself in the form of small round spots that are initially yellow and watery, and then become reddish-brown and tumble-down:

The symptoms of this disease are easily confused with manifestations of bacterial rot caused by Pseudomonas cypripedii.

Control measures: perhaps preventive spraying with tiram (3%), "Pseudobacterin-2", "Fitosporin-M".

Brown spot (Acidovorax avenae subsp. cattleyae, synonym: Pseudomonas cattleyae)

The disease begins with the appearance of small soft watery bubbles. These bubbles are green at first, but then they increase in size, the tissues fall through, and the lesions become brown or black. A fluid containing masses of bacteria flows out of them, especially when the lesion reaches the tailbone.

Control measures. This infection is easily transmitted through irrigation water, pests, as well as the tools that make cuts. Therefore, special care is needed when carrying out agrotechnical measures.

Tools, racks, dishes and drainage should be thoroughly disinfected. From the diseased plant it is necessary to remove the affected areas, not forgetting to process the tool after each cut. Since this pathogen prefers moist warm conditions, it is necessary to reduce humidity and temperature, as well as to avoid spraying the leaves. Chemical control methods are the same as for Erwinia carotovora.

What are noncommunicable diseases of orchids

Often, indoor orchid diseases are caused not by infection, but as a result of improper agricultural practices. They may suffer from a lack or excessive light, sunburn, improper spectral composition of light, low air humidity, imbalance of temperature regimes, unbalanced nutrition, the use of pesticides, etc. roots, non-flowering.

See what non-infectious orchid disease looks like in these photos:

Often, orchid growers are faced with a sudden appearance of depressed white and black spots on the leaves of phalaenopsis, which are considered to be manifestations of a viral infection. In fact, the primary cause of the appearance of such spots is a decrease in air temperature to 4 — 6 ° С (short one-time or repeatedly repeated over several nights in a row) or spraying the leaves with cold water.

Very light leaves indicate chlorosis, which is observed in epiphytic orchids in the case of iron deficiency, which is absorbed only in an acidic environment and becomes inaccessible to the plant in case of watering with hard water, using carbonate substrates, as well as with an excess of phosphorus fertilizers.

When treating this disease of domestic orchids, the manifestation of chlorosis can be eliminated by adding iron chelate to a slightly acidified solution of macrofertilizers and periodically carrying out foliar feeding of plants with microelements.

Colorless moist spots can appear on the leaves of frozen orchids, briefly kept at a temperature below 0 ° C. If frostbite does not affect the stem tissues (in monopodally growing orchids) or rhizomes (in sympodically growing orchids), areas with weeping spots should be removed immediately.

The other extreme of extreme temperature exposure is sunburn. Spots from instantaneous burns remain on the leaves until natural death, unlike the patches caused by pathogens, they do not increase in size.

But sometimes the deformation of the tissues is caused not by the sun's rays, but by the constantly high temperature, when the closed greenhouse is left on the sunny window. The direct sun may not fall on the leaves of the plants in it, but when the temperature in the greenhouse rises to 30 ° C and higher, the plants start to react, taking water from the tissues of the leaves, flowers, pseudobulb, roots. Such thermal burns appear gradually, and their consequences are much more dangerous.

In addition to sunburn and heat burns, chemical burns caused by overly concentrated subcortex or fungicides can also be noted.

The tender tips of young growing roots are most susceptible to chemical burns.

When the temperature drops at night, young leaves of monopodial growing orchids may suffer from water accumulated inside the leaf outlet. To avoid decay of the apical meristem and not to provoke a fungal or bacterial infection, water after irrigation should be removed by soaking it with a napkin. If the tip of the shoot is still rotten, it should be treated with a fungicide, and then be patient and wait for the awakening of the lateral buds of the shoot.

The appearance of deformities and spots on the forming peduncles, pseudobulbs, leaves and roots can be explained by many more reasons, from drafts to the banal bursting of cats or cockroaches.

Treatment of diseases of orchids at the time of care at home (with photo)

In the fight against pests and diseases, the most effective preventive measures. General recommendations - regular inspection of plants, keeping pots and work tools clean, steaming the substrate, weeding the reserves of pests, prophylactic spraying with biological fungicides consisting of dissimilar strains of active bacteria to prevent fungal and bacterial rot.

Do not allow water to stand on the leaves of plants, especially when there is a lack of light, as well as during long winter nights. For vegetative propagation, it is desirable to select only known healthy plants.

When transplanting, after each incision, you need to disinfect the instrument with alcohol, immediately after transplantation you need to clean the workplace from plant debris.

Introducing new plants into the house, they must be carefully examined. Various patterns and spots on the leaves and shoots, deformations of the nsevdobulb and leaf blades, soot fungus - all this indicates hidden diseases and pests that can appear soon after planting.

If in doubt, you need to allocate a special isolated place where for a while to put all the newly acquired orchids. Regular preventive treatment of this place with insecticides and fungicides is desirable. Such temporary isolation will help prevent the emergence of new pests.

It is possible to bring pests with the substrate, therefore, components of plant origin (land, peat, leaf litter, bark, sphagnum and others) must be checked for the presence of earthworms, leafworms, woodlice, slugs, snails, as well as their eggs. Steaming a freshly prepared substrate is one of the most effective preventive measures.

Orchids (especially their flowers) are quite sensitive to pesticides. Therefore, before chemical treatments, fungicides must be checked for phytotoxicity. Spray orchids early in the morning or late in the evening, avoiding the heat of the air and direct sunlight.

When combating a complex of pests (spider mites, flat red mites, thrips, coccides, woodlice) and diseases (fusarium and root rot, anthracnose and other spotting), it is possible to use combined mixtures of pesticides.

This photo shows the care of orchids at home, during the treatment of diseases:

Each combination of drugs must be coordinated with a special table of drug compatibility and must be preliminarily tested for specific types of orchids.

Working solutions of pesticides are usually prepared immediately before processing, strictly adhering to specified concentrations. For better wetting, stickers or surfactants are added to the solutions. Usually this soap (potash, liquid or household). Soap is diluted in a small amount of water and added to working solutions immediately before use at the rate of 3 — 4 ml per 1 l of solution.

When working with pesticides, special precautions are taken, exposed skin surfaces are protected with clothing and rubber gloves, and the respiratory tract is protected with a special respirator.

Eradicating chemical treatments with combined mixtures of pesticides, which are carried out against the complex of pests for the treatment of orchid diseases at home, should be timed to the periods of the greatest activity of pathogens. These terms usually fall in spring and late autumn. For example, during the year, outbreaks of breeding of worms and insects occur in February — March, July — August, and November — December.

The increase in the number of spider mites occurs in February — March, as well as May (exit from diapause), July — August (penetration from open ground) and October — November (decrease in air humidity due to the start of the heating season).

The maximum activity of pathogenic fungi occurs in the summer and autumn (especially before the start of the heating season).

Therefore, regular processing with combined mixtures of pesticides that are allowed for use in protected soil, carried out only twice a year - in spring (April) and autumn (end October-November) - are the most effective and pose the least danger to both human health and ornamental Orchid.

Remember that prolonged use of the same pesticides causes resistance to them in pests and pathogens. In order to overcome the resistance to pesticides, it is desirable to give preference to biological preparations, as well as alternate pesticides from different classes of chemical compounds (carbamates, phosphorus derivatives, pyregroids, etc.).

Here you can see photos of caring for orchids affected by diseases:

English EN russian RU