Brief introduction of Orchid Diseases

Orchids like warm and humid, appropriate shade, such an environment is also suitable for some diseases, especially the growth of fungal diseases, if not paid attention to. There will be serious consequences. The following is a brief introduction of the common diseases of orchids one by one for reference only.

I. fungal diseases

(1) Root rot

The root of the diseased plant browned, the root bark rotted and fell off, and lost the function of absorption. Its branches and leaves show malnutrition, insufficient water supply, weak stems and leaves, dwarf ratio, yellowing and atrophy. If the disease develops upward, it will lead to neck rot, leaf base rot, and eventually death, and the seedlings are susceptible to disease and easy to fall and die. There are four kinds of pathogenic bacteria.

1. Fusarium extreme rot

(1) Fusarium batatatls var.vanilllae Tucker

(2) F.oxysporiun Schlecht.f.sp.Cattlevae Foster

2. Rhizoctonia solani Rhizoctonia solani Kuehn

3. Sclerotiuln rolfsii (Sacc.) West small Sclerotinia sclerotiorum

(2) Black rot

Symptoms are similar to phase rot, extremely rot, neck rot, disease can develop good leaves, heart rot, the disease develops rapidly.

1. Phytophthora black rot phytophthora cactorum (Lebg. Cohn) Schroet

2. Pythium black rot Pythium ultimum Trow

(3) Leaf disease

Cause various types of disease spots on the leaves, the disease spots heal into patches, causing the leaves to wither.

1. Anthrax:

The corrugated black-brown disease spot can be seen at the leaf tip or leaf edge, and the disease spot expands into a large spot, with concentric wheel patterns and conidial basins with small black spots on the pattern. The disease can also infect sepals and petals when severely punished. It began in April and became popular from July to August.

(1) Colletotrichum orchidearuum Allesh of anthracnose

(2) C.orchidearum f.cymbidii allesh of anthracnose

(3) C:Gloeosqorioides penz C.cinctum (Berk.&.Curt.) sion C.gI000SpOOioides Penz of anthracnose in Huanshi.

2. Alternaria orchard spot Cylindrosporium phalaenopeis Swada is also called black spot disease. The disease spot garden formed oval-shaped black-brown spots, which mostly occurred at the base, margin or tip of the leaf. The center of the spot is grayish brown, no brown verrucous microsomes are born, and it is a conidial disc. 15-20C, overcast and rainy, high humidity, favorable for the disease, prevalent from January to April.

3. Cercospora leaf spot disease: the shape of the spot is changeable, brown to brown round to form irregular spots, slightly sunken, the edge of the spot is dark, or there may be yellow halo. Some occur on the back of the leaf.

(1) Cercospora Epipatidis C.Massalollgs

(2) C.PCristeriae Btlrnett

(3) C.Dendrobii Burney

(4) C.angraeci Feuill&.Roum

(5) C.cypripedii Ellis & Dearmess

(6). C.odontoglossi Pril.g.Dclac

(7) C.sPP.

4. Alternaria leaf spot Septoria elenoPhompides Cash g.Watson

5. Leaf spot mildew Phollostictina Pyrifomis Cash & Watsom

6. Penicillium leaf stain disease Diplodia laeliocattleytae Sibilla

7. Coal pollution disease Gloeodes pomigena (Schw) Colby. Leucosporium myxosporium, often growing on the surface with fly droppings.

It does little harm to orchids.

8. Microthyriella rubi Petr. Muscidae, needle-shaped patches on both sides of the leaf interweave into a black cover, saprophytic on the leaf surface.

9. Soot disease Capnodium citri Bcrk.& Desm. Citrus coal fungus. Saprophytic on insect exposure.

10. Rust: spores are piled on the back of the leaves, and yellow-green discoloration spots are seen in the corresponding parts of the leaves.

(1). SrhenosPora kevorkialnii Lhlder orange-brown teliospore pile.

(2). S.Mera Cumm. Brown spore pile

(3) S. Saphena Cumm. Rusty brown teliospore pile.

(4) S. epidendri P.Hemm. Orange county spore pile

(5). Uredo behnickiana P.Henn orange summer spore pile

(6) U. Nigropuncta P.Henn. Black summer spore pile

(7) U.Oncidii P.Henn orange summer spore pile.

11. Other fungal diseases:

(1) Alternaria sP.

(2) Cladosporiun SP.

(3) Helminthosporiunm sP

(4) Gloeosporium sP

twelve。 Snow rot Ptychogaster sp. Alternaria, white mildew mycelium saprophytic on the medium carrier of orchid made by fern and Chinese fir bark.

13. Petal diseases:

(1). Scorch blight Botrytis cinerea Pers. Staphylococci.

(2) Curvularia eragostidis (Heen) Meyer Curvularia.

II. Bacterial diseases

L. Brown spot Pseudomonas cattleyae (povarino) Savulescu Pseudomonas aeruginosa infects orchid leaves into brown patches, and bacteria overflow can be seen in wet weather.

2. Soft rot Etwinia Carotovora (Jones) Helland causes tender meat such as pseudobulbs and rhizomes.

The tissue is soft and rotten and has a bad smell. The leaves on the ground lose their luster, and when the disease is serious, the leaves droop and die.

3. E.cyvipedii (Hori) Bcrg et al Eucalyptus caused damage in the middle of the leaves to egg orchard-shaped water-flooded yellow spots, and then turned brown. if the leaf growth point was invaded, the shoot would dry up and die.

III. Virus disease

The same virus has different symptoms in different orchids, such as mosaic, mottle, necrosis, ringspot, deformity, arbuscular branch, dwarfism or occult disease, as well as compound symptoms. Wild orchids are rarely susceptible to diseases transmitted by juices, tools or insect vectors.

1. Orchid mosaic virus CyMV Cymbidium Mosaic Virus showed mosaic symptoms, clear stripes and necrotic stripes in Jian Lan and Cymbidium in Guangzhou. The disease is transmitted through juices or peach aphids. The virion line 475-490*13nm is similar to the particle of potato virus X.

2. Orchid broken color virus disease, TMV-O strain, also known as tooth orchid ringspot virus Odontoglossum Ringot Virus, 300*18nm rod-shaped particles transmitted by juice and aphids.

3. Cymbidium necrotic spot virus disease Orchid fleck V.

Japan reported that mottled, necrotic, juice-borne particles short rod 15O*40um. Nm=10-7cm

4. Nematodes:

Yellow bud blight nematode Aphelenchoides ritzcma-bosi (Schwartz) Steiner&.Buhrer slippery blade nematode is also harmful to Compositae and weeds.

5. Parasitic plants: harmful terrestrial orchids

(1) Cassytha filiformis L.

(2) Cuscuta gronovii Willid.

VI. Physiological disorders

Due to high temperature and low humidity, flooding, lack of water, sunburn, overfertilizer, lack of elements, drug damage, air pollution and water pollution can cause physiological disorders of orchids, such as mosaic, mottling, yellowing, spots, patches, necrosis, atrophy, distortion. The symptoms of similar infectious diseases are often difficult to distinguish, and the causes can only be clarified through pathological analysis.

1. Element deficiency: for example, in general, plants with severe element deficiency show the following: typical symptoms of calcium deficiency, zinc deficiency, copper deficiency, magnesium deficiency and sodium deficiency are etiolation and necrosis. The symptoms of deficiency of nitrogen, phosphorus, iron, magnesium, molybdenum and sulfur are discoloration of leaves, similar to the symptoms of viral disease. Lack of potassium, brown patches on both edges of the leaf.

2. Fertilizer damage

The main results are as follows: (1) when sulfate and chloride and fertilizer are used for a long time, the soil root is damaged due to the accumulation of compounds, which affects the function of absorption.

(2) ammonia (NH3), nitrous acid (NO2) and sulfite (SO3) were produced from fertilizers such as urea and ammonium sulfate, which caused poisoning of ammonia, sulfur dioxide and nitrogen dioxide, and the leaves first showed symptoms such as black spot, wilting and death.

3. Drug damage: dark brown and necrotic spots, and die in severe cases.

(1) Copper agent and stone sulfur mixture are easy to cause drug damage at high temperature.

(2) Burning spots will occur at the leachate after the application of surfactants in emulsions and agents.

(3) floating drugs using herbicides or other growth regulators in the surrounding farmland enter the flower bed and cause damage.

4. Environmental pollution

(1) Air pollution: emissions from automobiles, soot, natural gas and oil refineries contain hydrogen sulfide, sulfur dioxide, hydrogen fluoride, ethylene and plasticizers such as n-butyl and diisobutyl phthalate in large boron plastics (polyethylene and polyvinyl chloride). Dioctyl adipate can cause toxicity.

Ethylene and gasified diisobutyl ester containing 0. 1 to lPPM in the greenhouse will cause withered leaves, petal loss, flower drop, drooping leaves and other symptoms.

(2) Water source pollution: three wastes from factories, and water sources are polluted by metals, non-metals, organic substances, pesticides and radioactive substances. Irrigation water is also a means of transmission of diseases and insect pests. Therefore, the artificial irrigation water for flower cultivation must be free of clean water sources polluted by acid, alkali, heavy metals, diseases and insect pests, and it is best to be filtered before use. (Liu Chaozhen)