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White mold affects a wide range of hosts and causes sclerotinia stem rot. It is known to infect 408 plant species. As a nonspecific plant pathogen, [3] diverse host range and ability to infect plants at any stage of growth makes white mold a very serious disease. The fungus can survive on infected tissues, in the soil, and on living plants.
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.
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 ...
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] Symptoms of this pathogen include stunting and chlorosis. [2]
The English name 'common spotted' refers to the species' abundance and the spots on its leaves. The French and German common names also honour Leonhart Fuchs. This plant belongs to a problematic group of orchids. D. maculata subsp. fuchsii is very variable in flower colour and flower morphology, plant height and the scent of flowers.
Cephalanthera austiniae is a species of orchid known as the phantom orchid and snow orchid [2] because the entire plant is white except for a few yellow markings on the flowers. The orchid is native to the western United States ( California , Oregon , Washington and Idaho ), and to British Columbia , Canada.
Orchid mycorrhizal interactions can range from wholly parasitic on the fungal partner, to a mutualistic interaction involving bidirectional nutrient transfer between the plant and mycorrhizal fungus. [32] [33] Orchid plants have an obligatory parasitic life stage at germination where all of their nutrients must be supplied by a fungus. [34]
Hot and dry conditions in the summer cause the fungus to become inactivated and the leaf spots to turn white and crusted. [11] During the summer, the diseased leaves fall leaving only the healthy ones on the partially defoliated trees. This provides a natural control for the disease. [5] The disease also mainly infects young leaves in the ...