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Fungi and Bacteria  nas Orchids

        Before talking about diseases, it is important to clarify that there are both fundamental fungi for the good growth of orchids and those that cause diseases. It is important to bear in mind that they are always present and when favorable conditions exist, they develop in a way that damages the orchids. These conditions can be summarized as lack of ventilation, excessive humidity and excessive shading.   So this is the first,  main and most effective step for your fight.

dots on the leaves 
spots on the leaves 

Fungi that cause disease in orchids:


Aecidium graebnerianum

Alternaria spp. - Blemishes and necrosis on flowers and buds;

bipolaris setariae- spotted flowers 

bipolaris sorokiniana- spotted flowers

Bipolaris spp.-  spotted flowers

Botryodiplodia oncidii - Rear death

Botryotinia fuckelian- gray mold, stain and rust on flowers;

Botrytis cinerea- soft rot

capnodium citri- fumargina 

Cephaleuros virescens- Seaweed-like stain

cercospora angreci- stained leaves

Cercospora cypripedii- stained leaves

cercospora dendrobii- stained leaves

Cercospora epipactitis- stained leaves

cercospora odontoglossi- stained leaves

Cercospora peristeriae- stained leaves

Chaetodiplodia sp.- stained leaves

Colletotrichum bletae- Anthracnose (Bletia)

Colletotrichum coccodes- Anthracnose

Colletotrichum crassipes- Anthracnose

Colletotrichum dicheae- Anthracnose

Colletotrichum gloeosporioides- Anthracnose

Colletotrichum orchidearum- Anthracnose

Colletotrichum roseolum- Anthracnose (Bletia)

Coniothyrium sp.- stained leaves

Corynespora cassiicola- stained leaves

curvularia sp. -  leaf necrosis

Diplodia bulbicola- stained leaves

Diplodia laelio-cattleyae- stained leaves; stem fall;

Diplodia paraphysaria- stained leaves

diplodia sobali- stained leaves

Fusarium cattleyae  - Fusarium wilt 

Fusarium moniliforme- soft rot;

Fusarium oxysporum- pseudobulb rot and root rot 

Fusarium oxysporum f. Sp. Cattleyae- pseudobulb rot and root rot 

Gloeodes pomigena- soot-like stain 

gloeosporium affine- European anthracnose

Gloeosporium cattleyae- Anthracnose

Gloeosporium epidendrii- Anthracnose

Gloeosporium laeliae- Anthracnose

Gloeosporium oncidii- Anthracnose

Gloeosporium pallidum- Anthracnose

Gloeosporium stanhopeae - Anthracnose

gloesporioides- Anthracnose

Glomerella cincta- Anthracnose

Glomerella cingulata- Anthracnose

Guignardia spp.- spots on the leaves

Hemileia oncidii- rust

Lasiodiplodia theobromae- rust

Macrophoma cattleyicola - 


Macrophoma oncidii- fungal stain 

Behnickian Nectria- fungal stain 

Nectria bolbophyli- fungal stain 

Bulbicola Nectria- dry cinnamon

Phoma spp.

Phyllosticta capitalensis- lesions and spots on the leaves, chlorosis;

Phyllosticta pyriformis- Yellow spots 

Phyllostictina pyriformis- fungal spots 

Physalospora cattleyae- Anthracnose; fungal spots

Physalospora orchidearum- Anthracnose

Phytophthora cactorum- black rot, brown rot, leaf rot; pseudobulb and root rot. 

Phytophthora cinnamomi - leaf, pseudobulb and root rot. 

Phytophthora nicotianae-rot

Phytophthora palmivora- root rot, black rot 

Pleospora orchidearum- fungal stain

Pseudocercospora spp.

Puccinia cypripedii

Pythium splendens- rot of leaves and shoots.

pythium ultimum- black rot, leaf rot, brown rot;

Rhizoctonia solani- root rot and pseudobulbs  

Schizothyrium perexiguum- small stain resembling insect excrement.  

Schizothyrium pomi- small stain resembling insect excrement.

fuckelian sclerotinia- rust on the petals

Sclerotium orchidearum- basal, leaf and pseudobulb rot.

Sclerotium rolfsii- rust;

septoria selenophomoides- leaf spots until the pseudobulbs fall off 

Sphenospora kevorkianii-rust 

sphenospora mera-  rust

Sphenospora saphena- rust

Stibella bulbicola

tubercularia cattleyicola- rust

behnickiana uredo- rust

uredo epidendri- rust

uredo guacae- rust

uredo nigropuncta - rust

Volutella albido-pila- subsidence of pseudobulbs;

Volutella Concentrica- stains on the leaves 

Volutella pachysandra- rust. 

Zythia nepenthis


podridão negra

black rot(Pythium ultimum and Phytophthora cactorum)


      One of the biggest nightmares of every collector. One of the fastest and most devastating presentations of fungal pathogens on orchids. Under ideal conditions, the speed of propagation is such that a seedling can rot in less than 24 hours after the appearance of the first signs.   So we are talking about a disease that always requires urgent intervention. 

     Os causadores da podridão negra são dois fungos: Pythium ultimum e Phytophthora cactorum, que can act alone or together.

podridão negra em orquideas, phytium ultimum, phytophtora cactorum, brotos apodrecem

        are water dependent fungi. The spores swim through the water, like water lodged in the leaf, and then penetrate the orchid's tissues. Once it penetrates the tissues, it causes rotting, generating black and watery spots. The liquid that comes out when squeezed is highly contaminating. 

       A germinação dos esporos ocorrem entre 4,5 e 35C, otimizado entre 16 and 25C. The attack can start in any part of the plant, but preferably in the soil line and young parts (shoots) and progress to the whole plant until it reaches the roots._cc781905-5cde-3194- bb3b-136bad5cf58d_

        Some points must be taken into account for prevention. Never use unsterilized pots; keep the vases at a distance of at least one meter from the floor to avoid splashing water from the floor; Do not let the leaves of your orchids stay wet for a long time and, above all, ensure a lot of ventilation for your plants. 

      _cc781905-5cde-3194-bb3b-136bad5cf58d In case the contamination happens too much should be separated immediately. avoid contagion.   Fertilizers with high concentrations of calcium can help prevent new shoots. 

      _cc781905-5cde-3194-bb3b-136bad5cf58d safe tissue margins affected aste aste. After cutting, make sure that there are no signs that the lesion is already advancing in the part of the tissue that was left (usually brownish streaks). Then place the plant in a dry and ventilated place. Let the plant dry. However, if the plant is of lesser value and easily replaceable, perhaps you should consider disposing of the plant complete with pot and all. 

       O controle químico com fungicidas sistêmicos pode ser necessário no caso de ataques severos.  Pulverização  com solução de Bordeaus a 1% ou 0.2% de oxicloreto de cobre ou Fosfato de potássio a 0.4% .















podridão negra em orquideas, phytium ultimum, phytophtora cactorum, brotos apodrecem
podridão negra em orquideas, phytium ultimum, phytophtora cactorum, brotos apodrecem
podridão negra em orquideas, phytium ultimum, phytophtora cactorum, brotos apodrecem
fungos em orqudieas, fusariose, canela seca, fusarium oxysporum

Fusariosis (Fusarium Oxysporum, Fusarium solani)


      This is a soil fungus that enters through the vascular system and spreads through the xylem, where it settles, popularly _cc8905-7 5cde-3194-bb3b-136bad5cf58d_known as "Cinnamon Dry". It is a difficult to control fungus characterized by the destruction of the vascular system.  Another very common form of contagion in cultivation is through damage to the rhizome, such as when cutting to propagate seedlings.   Its development is ideal between temperatures of 25 to 30C, precisely the best temperature for the development of orchids of the genus Cattleya, for example. 

         Os sintomas começam nas raízes e advance towards the leaves, characterized by making the leaves easily detachable.  The rhizome acquires a reddish color and, when cut, a purple-brown ring is clearly visualized due to the accumulation of toxins produced by the fungus. (Photos)

fungos em orqudieas, fusariose, canela seca, fusarium oxysporum

       Os simtomas são mais visíveis nas partes velhas da orquídea, mas como o tempo the young parts end up being effected. It is known to be a fungus of slow evolution, since, depending on the health of the plant, it can take many months before it leads to death. This makes this fungus often overlooked among collectors, a serious mistake. Even so, it must be taken into account that it can kill an orchid in just one month.

         Não costuma gerar sintomas em folhas ; In the roots, the infection starts with a brown spot that evolves into dry rot, forming constricted areas like a neck. 

      _cc781905-5cde-3194-bb3b-136bad5cf58_color The leaves usually acquire a color_


fungos em orqudieas, fusariose, canela seca, fusarium oxysporum

reddish, it is a chlorosis that will end with the fall of the leaf. It can also affect the flowers, causing dry necrotic spots to appear on the floral peduncle, causing the flora to drop prematurely. 



too much, when other types of parasites attack the plant due to fusariosis injury, destruction is often recommended to prevent spread to other plants.   Chemical pesticides are not very efficient, the main recommendation being the association of Cyprodinil + Fludioxonil.  Carbendazim, Thiophanat-methyl and Prochloraz are not enough and cause a slowdown in orchid growth._cc781905-5cde-3194-bb3b-58d6_bad

       Duas a tres pulverizações com 0.20% _cc781905 -5cde-3194-bb3b-136bad5cf58d_de Carbendazim ou 0.20% Thiophanate methyl with an interval of 15 days  A mixture of Carbendazim a 0.20% is also effective.


Rhizoctoniosis (Rhizoctonia solani)


      This is also a soil fungus, which means that it comes from the substrate to attack the plant. Thus, it should be made clear that the greatest form of contagion is precisely the use of poor quality substrate, contaminated by spores of this fungus.  Substrate that has contact with soil is a strong candidate for spreading the disease. It is a complex species composed of several strains, not all of which cause disease, forming part of Michorryza in the soil. 

      _cc781905-5cde-3194-bb3b-136bad5cf58 disease starts below ground line develop towards aerial parts. DIt develops between temperatures from 12 to 35C   with a peak between 20 and 30C. Unlike Pythium and Phytophthora, Rhizoctonia does not require high soil moisture to infect the plant.   Rhizoctonia also does not form spores, only a dense mycelium over organic matter. 

fungos em orqudieas, raízes podres, rizoctoniose, rhizoctonia solani

      Brown spots can be seen on roots, stems and leaves. In high humidity environments, lesions grow rapidly with the mycelium clearly visible to the naked eye. When they reach the leaf, the rot usually appears at the base of the leaf, which causes it to fall in sequence. Still, in older plants, clear symptoms are often not observed, with only hampered growth. 

       Por fim, os simtomas são muito semelhantes ao causados pelo Fusarium oxysporus, com the differentiation that in the case of Fusarium the typical reddish ring appears on the rhizome.  


(Colletotrichum gleosporieoides,  Glomerella cingulata)


         Do grego Anthrax = negro como carbon and Nodos = disease.

        It is a  large and very common group of fungi that attack the aerial part of orchids, especially the leaves.  Podem start o attack from the tip of the leaves evolving towards the bases (Colletotrichum) or at any point on the sheet (Glomerella).

      _cc781905-5cde-3194-bb3b-136bad5cf58d The main characteristic of the stains is from brown to gray the formation of clearly defined rings or geometric shapes in the affected part while the rest of the leaf appears normal. With the help of a magnifying lens, spore formation can be seen over the affected area. 

If the affected area is in the flowers, dark pustules form, slightly raised on the underside of the sepals and petals, and can evolve to the entire flower. 


      Its appearance is related to high humidity, and contagion usually occurs through splashes of water._5cc-78190 5cde-3194-bb3b-136bad5cf58d_

    Para o controle é indicado cortar as partes afetadas e o uso de fungicidas a base de tiofanato methyl  as a preventive measure. 

         Em caso de controle severo, fungicidas a base de Azoxystrobina, Difeconazol e Bitertanol costumam ser efetivos. 


Podridão Bacteriana

bacterial rot

(Erwinia Carotovora, Erwinia cypripedii, Acidovorax avenae)


      Bacteria are single-celled organisms that move through water. This already points to a great dependence on this water so that it can follow its life cycle and reproduction, pointing to the main cause of bacterial problems in orchids: the excess of water.

      _cc781905-5cde-3194-bb3b-136bad5cf58d are needed only a few minutes in your presence water heat, so that a bacterium already begins to divide, forming new individuals. In this way, in a few minutes, one becomes two, which divide again into 4, then 8, 16, 32, 64... and quickly they have already taken over your orchid. _cc781905-5cde- 3194-bb3b-136bad5cf58d_


      The optimal temperature for the development of bacterial diseases is 25 to 30 degrees. -136bad5cf58d_

        Importante ter em mente que uma bactéria it is not capable of generating infection in the orchid. In order for there to be infestation, there must be an injury that allows the bacteria to enter the plant. This lion can be generated either by handling (scissors, knives...) spiders or even insect bites. 

       A lesão causada pelas bactérias Acidovorax  e Erwinia are physically different. 


      Lesions caused by bacteria of the genus Erwinia start as yellow spots on the leaves, usually starting at the base of the leaf, advances throughout the leaf turning it into a rotten mass. A kind of slime forms.  Erwinia has the potential to attack virtually all orchid species. 

      _cc781905-5cde-3194-bb3b-136bad5cf58d already prefers Cattleaxido. Initially the lesion appears as a small black dot. If the leaf is held up to the light it is possible to see a yellow circle around the black dot. The tiny dots bind together into a uniform mass, causing plant tissue to collapse. Acidovorax can infect flowers.  Erwinia is more common in winter and Acidovorax in summer.

      _cc781905-5cde-3194-bb3b-136bad5cf58d In practice, causing several injuries at the same time, bacteriad and the exact definition of the causative bacteria can only be identified through exams

 A, B - infected leaf surface; C- Underside of infected leaf.

D and E - darkening/old lesion; F - bulb lesion; G - lesions paralyzed by fungicide; H - microscopic image of the bacteria; I - home injury by artificial inoculation. 


      _cc781905-5cde-3194-bb3b-136bad5cf58d is always the best way to control bacterial diseases seek to generate better growing conditions.   Pay close attention to excessive humidity, lack of light and lack of ventilation. Avoid injuries, because they are the gateway to bacteria.   If you notice an affected plant, it must be immediately removed from the nursery and destroyed.  Cutting only the affected leaves normally just slows down the situation and even opens up the possibility of more plants being infected. In the event that a plant is infected in a collective, the ideal is to destroy the entire collective.   Every type of stress favors the appearance of diseases, try to keep the culture as regular as possible. Fertilization with excess nitrogen also favors attack by bacteria and even fungi. Hygiene in cultivation must be a priority, including the constant disinfection of all tools. 

          Poucas são as opções de chemical control, with products based on agrimycin and kasugamycin indicated. 



Summa Phytopathol., Botucatu, v. 40, no. 3, p. 290, 2014

Australasian Plant Disease Notes, 2009, 4, 65 - 66


(Uredo behnickiana, Uredo nigropuncta, Sphenospora kevorkianii, Puccinia sessili)


    The name Rust comes from the appearance of the pustules formed by these classes of fungi on the leaves, resembling rust resulting from the oxidation of iron. 

        Sphenospora kevorkianii _cc781905-5cde-3194 -bb3b-136bad5cf58d_ is the species most commonly found in orchids.   

  Uredo behnickiana has yellow-orange spots on the underside of the leaf. Young spots are small but rapidly enlarge in a circular pattern and may occupy the entire leaf face. On the upper side, immediately opposite the stain, pale yellow chlorotic spots appear.

        Já na infestação por Uredo guacae, inicialmente aparecem também pequenas manchas laranjadas que , as they age they turn black. Sometimes the development is concentric with the lesion appearing like a target.   Black and orange areas of rupture appear on the upper surface. 

Australasian Plant Disease Notes, 2009, 4, 62–63

       A infestação por Hemileia Oncidii também inicia com pequenas pustulas amareladas que, na medida As the disease progresses, they turn brown while the growing margins continue to turn yellow.

      _cc781905-5cde-3194-bb3b-136bad5cf58d Once the symptoms are identified, cut the sheet affected and burn. Spraying with copper-based products is efficient, but be careful with phytotoxicity. 



(Cercospora Sp. )


       A infecção por cercospora quase sempre se inicia na face inferior das folhas, já que o fungus usually penetrates through the stomata;  10 to 20 days after infection the lesion appears  as a yellowish dot. In a few days  the lesion advances and will also be seen on the top of the leaves. The spots increase in size irregularly, leaving the region slightly sunken and necrotic, assuming a brownish color. The advance of the infection can evolve to the whole leaf. The margin of the growing lesion remains yellowish. Leaf fall can be quite premature.  Fungicidas a base de cobre, Captan, azoxystrobina, pyraclostrobina e thiophanato-methyl_cc781905-5cde-3194 -bb3b-136bad5cf58d_usually control the infection; 



(Phyllosticta capitalensis)


       The names Pyllosticta and Guignardia are names that apply to two stages of sexual maturation of the same fungus.  3194-bb3b-136bad5cf58d_

       small purple spots that appear in the first two purple spots sides of the sheet. Lesions usually follow elongated or diamond-shaped leaf veins.   Sometimes the lesions merge, generating large irregular lesions. With aging, the center of the lesion appears burnt; to the touch, it looks like sandpaper. 

         Uma vez contaminada, é praticamente impossible to eliminate the fungus from the plant. Although Phyllosticta does not kill  an orchid, it can weaken the plant to the point where it_cc781905-5cde-3194-bb3b-136bad5cf5 prey_easily pests or diseases.

      _cc781905-5cde-3194-bb3b-136bad5cf58 presence fungi and ascospores. Conidia are transported by water, including splashes, while ascopores are easily spread by air. 

The development of the fungus is very difficult in high light and dry environments. 



(Sclerotium rolfii. )


        The Sclerotium rolfii lesion occurs at the base of the leaves as a brown spot. As this lesion causes local necrosis, it ends up interrupting circulation to the rest of the leaf, causing it to wilt.   As in most fungal attacks, around the necrotic region (brown) there is a yellowish area, which is the part where the fungus is still growing. 

      _cc781905-5cde-3194-bb3b-136bad5cf58d The development of organic substrates is related to the temperature of this fungus_ and high humidity. 

          É_cc781905-5cde-3194 -bb3b-136bad5cf58d_a fungus that lives in the soil (where it can lie dormant for many years) and does not form spores, much like Rizhoctonia. It needs high temperatures to develop (ideal between 27 and 30 degrees). It needs a lot of oxygen to develop, so the infestation starts above the substrate and the roots inside the substrate are not affected. 


spots on the flowers

(Botrytis cinerea)


        Also known as gray mold, perhaps one of the most frustrating diseases for the orchid grower: after a year of very careful care, he it can ruin the flower in a few days.   Interestingly, they do not cause major problems in the vegetative part of the orchid, attacking only the flowers. 

          _cc781905-5cde-3194 -bb3b-136bad5cf58d_ For its propagation, it requires humid and cold weather, and its spores are easily transported by wind and water.  

          _cc781905-5cde-3194 -bb3b-136bad5cf58d_  Flowers can be sprayed every two weeks with fungicides based on chlorothalonil. The vegetative part (not flowers) can be preventively sprayed with products based on quaternary ammonium. 

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