Analysis of Cases of Orchids with No Typical Symptoms

Typical symptoms are representative disease signs. For example, coughing is a typical symptom of respiratory diseases. Commonorchiddiseases also have typical symptoms. The early typical symptom of brown spot disease is extremely fine brown spots appearing on the leaves; in the late stage, the spots enlarge into semicircular, slightly sunken, ring-like black patches. The early typical symptom of southern blight is white thread-like material (mycelium) appearing at the base of the orchid plant; in the late stage, the white thread-like material spreads across the entire pot surface, and the base of the orchid plant becomes water-soaked and rots. The early typical symptom of leaf spot disease is brown lesions appearing at the base of new leaves (shoots); in the late stage, the brown lesions rot, and with a gentle pull of the hand, the leaf comes away with it. The early typical symptom of viral disease is various patterns resembling leaf variegation appearing on the leaves; in the late stage, the leaves wither, blacken and die. No typical symptoms means there are no special representative disease signs.OrchidThe whole process of death from disease with no typical symptoms is that the leaves lose water and wither, while the roots remain fresh and alive as before after death. It is said to have no typical symptoms because its symptoms are no different fromorchidnatural death, except that natural death only kills old plants and does not affect new plants or new shoots, whereas this disease does not distinguish between new and old plants - as long as they are connected in a clump, they inevitably die. Secondly, its symptoms are also very similar to those of poor management. For example, the symptoms of orchid poisoning from excessive pesticide dosage are also like this, but poisoned leaves often have spots or patterns, while this disease leaves no trace at all. The symptoms of root rot from overly concentrated fertilizer are also the same, with the difference being that root rot symptoms usually begin with water loss and wrinkling at the leaf tips or new leaves, while this disease shows no abnormal warning signs. Growing media that is too dry or too wet also produces similar symptoms. In fact, there is a fundamental difference between diseases with no typical symptoms and diseases from poor management: the former are pathological symptoms, while the latter are physiological symptoms. Diseases from poor management are chronic, have a longer course, and are reversible. For example, pesticide poisoning is mostly mild and slow, and can be remedied by stopping application and rinsing the leaf surfaces. The course of root rot from fertilizer damage is also very slow; as long as the growing media is replaced and fertilizing is stopped, generally not all plants will die. Diseases with no typical symptoms are acute, progressively developing, and irreversible. Last year, the author divided a large pot ofCymbidium sinenseinto 4 portions and gave them to several orchid friends to cultivate, and as a result all of them contracted the disease with no typical symptoms and died rapidly. While you are still staring in a daze, the orchid has already died. The pathogens of diseases with no typical symptoms are mostly brought in when orchids are introduced from other places. In November 2003, the author mail-ordered a batch of orchids from a certain place in the south and cultivated them with warmth in a heated cabinet. In mid-April 2004, when the new shoots had grown to 3cm, suddenly 2 pots ofCymbidium sinenseand 1 pot ofFour SeasonsOrchidcontracted the disease with no typical symptoms and withered to death. Locally, this disease has appeared only in thetwohouseholds that introduced orchids from other places, while among orchid friends cultivating traditional Jiangsu-Zhejiang orchids and localwild-collected orchidsandlarge orchid-growingoperations, no such situation has been heard of. At present, it is still unclear what the pathogen of diseases with no typical symptoms is, and prevention and treatment with commonly used orchid antibacterial agents has also proven ineffective. The author believes that once a diseased plant with no typical symptoms is found, it should be burned immediately, and the pots, tools and growing media that have been used should be strictly sterilized to prevent spread and reinfection. (Zhejiang Lao Tie)