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Odontoglossum ringspot virus (ORSV) is a plant pathogenic virus that belongs to the family Virgaviridae. It is one of the most common viruses affecting cultivated orchids, perhaps second only to the Cymbidium mosaic virus. [1] It causes spots on leaves and colored streaks on flowers. [1]
Black rot on orchids is caused by Pythium and Phytophthora species. [1] Black rot targets a variety of orchids but Cattleya orchids are especially susceptible. [1] Pythium ultimum and Phytophthora cactorum are known to cause black rot in orchids. [1] Pythium ultimum is a pathogen that causes damping-off and root rot on plants. [2]
Orchid fleck dichorhavirus, commonly called Orchid fleck virus (OFV), is a non-enveloped, segmented, single-stranded (ss) RNA negative-strand virus, transmitted by the false spider mite, Brevipalpus californicus. OFV causes necrotic and chlorotic lesions on the leaves [1] of many genera in the family Orchidaceae.
Symptoms of infection include a downward curling of the leaves, leaf tip dieback, stunting, necrosis of growing leaf tips, sunken 'chicken pox-like' spots on leaves (often with a surrounding halo), stem death and yellowing. [7] Since these symptoms are so generic, extreme caution must be taken when introducing new plants to your greenhouse.
Outside of the "maculata group", D. majalis is very similar to D. maculata subsp. fuchsii, but is distinguished by the following characters: the spots of the leaves are less elongated, the bracts of the inflorescence are longer and the lower transcend the inflorescence itself; it tends to be less cylindrical (a little more 'globular'), the stem ...
Other fungicides such as zineb, chlorothalonil and Captan, also treat leaf spot disease and Benomyl specifically treats Cercospora leaf spots, cherry leaf spot and black spot of roses. [7] Thiabendazole is used to treat leaf spot diseases of turf and ornamentals. [7] Both fenarimol and nuarimol are pyrimidines that also treats leaf spot disease.
The leaves are oblong or oval-lanceolate, with dark ellipsoid-shaped spots on the surface (hence the species name). The leaves are amplexicaul and can be either radical (basal) or cauline. The underground part of the stem has two webbed tubers, each deeply divided into several lobes or tubercles (characteristic of the genus Dactylorhiza ).
Dendrobium is a genus of mostly epiphytic and lithophytic orchids in the family Orchidaceae. It is a very large genus, containing more than 1,800 species that are found in diverse habitats throughout much of south, east and southeast Asia, including China, Japan, India, the Philippines, Indonesia, Australia, New Guinea, Vietnam and many of the islands of the Pacific.