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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] If a plant is also infected with the Cymbidium mosaic virus, it can lead to a condition called blossom brown necrotic streak. [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]
The virus has not often been reported in wild orchid populations. [2] It can be found in a wide variety of orchid genera [3] but does not infect plants other than orchids. [2] Once an orchid is infected, the virus spreads throughout the infected plant in a number of weeks. [4] Control measures may include sanitizing pruning equipment between ...
Orchid blooms drop off eventually from natural causes, of course, but if the flowers are falling off prematurely, there may be a problem. 1. Sudden Temperature Changes
When lettuce is infected with INSV, it shows a number of symptoms, such as yellowing leaves, dead spots, and stunted growth. On the inner leaves there are patterns of necrosis and chlorosis. At the base of the ribs of infected lettuce plants there is significant necrosis and lesions. The necrotic tissue can look brown to dark brown.
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.
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.
Cercospora is a genus of ascomycete fungi. Most species have no known sexual stage, and when the sexual stage is identified, it is in the genus Mycosphaerella. [2] Most species of this genus cause plant diseases, and form leaf spots.