Witch's broom or witches' broom is a deformity in a woody plant, typically a tree, where the natural structure of the plant is changed. A dense mass of shoots grows from a single point, with the resulting structure resembling a broom or a bird's nest. It is sometimes caused by pathogens.
Witch's brooms on downy birch, caused by the fungus Taphrina betulinaWitch's broom on a white pine.Witch's broom in Yamaska National Park, QC
Diseases with symptoms of witches' broom, caused by phytoplasmas or basidiomycetes, are economically important in a number of crop plants, including the cocoa tree Theobroma cacao,[1]jujube (Ziziphus jujuba)[2] and the timber tree Melia azedarach.[3]
A tree's characteristic shape, or habit, is in part the product of auxins, hormones which control the growth of secondary apices. The growth of an offshoot is limited by the auxin, while that of the parent branch is not. In cases of witch's broom, the normal hierarchy of buds is interrupted, and apices grow indiscriminately. This can be caused by cytokinin, a phytohormone which interferes with growth regulation. The phenomenon can also be caused by other organisms, including fungi, oomycetes, insects, mites, nematodes, phytoplasmas, and viruses.[4] The broom growths may last for many years, typically for the life of the host plant. If twigs of witch's brooms are grafted onto normal rootstocks, freak trees result, showing that the attacking organism has changed the inherited growth pattern of the twigs.[4]
Ecological roleedit
Witches' brooms provide nesting habitat for birds and mammals, such as the northern flying squirrel, which nests in them.[5][6]
Phyllody, a related plant growth abnormality affecting flowers
Referencesedit
^Purdy, L.H.; Schmidt, R.A. (1996). "Status Of Cacao Witches' Broom: Biology, Epidemiology, and Management". Annual Review of Phytopathology. 34 (1): 573–594. doi:10.1146/annurev.phyto.34.1.573. PMID 15012557.
^Li Yun; Wang Yu; Tian Yanting & Sun Haoyuan (2001). "Advances in Tissue Culture and Eliminating of the Pathogeny of Witch Broom Disease(MLO) of Chinese Jujube". {{cite journal}}: Cite journal requires |journal= (help)
^Gomez, G.G.; Conci, L.R.; Ducasse, D.A.; Nome, S.F. (1996). "Purification of the Phytoplasma Associated with China-tree (Melia azedarach L.) Decline and the Production of a Polyclonal Antiserum for its Detection". Journal of Phytopathology. 144 (9–10): 473–477. doi:10.1111/j.1439-0434.1996.tb00327.x.
^ abBook of the British Countryside. Pub. London : Drive Publications, (1973). p. 519.
^Mowry, Robert A. (2008). "Northern Flying Squirrel" (PDF). Alaska Department of Fish and Game. Retrieved 2 June 2020.
^Paragi, Thomas; Rodman, Sue (2020). "Maintaining wildlife habitat in the boreal forest of Alaska" (PDF). Alaska Department of Fish and Game. pp. 18–19. Retrieved 2 June 2020.
External linksedit
Media related to Witch's broom at Wikimedia Commons
witch, broom, confused, with, mistletoes, which, host, plant, tissue, parasitic, plants, growing, host, broom, associated, with, witches, besom, nebula, witch, broom, nebula, witches, broom, deformity, woody, plant, typically, tree, where, natural, structure, . Not to be confused with Mistletoes which are not the host plant s own tissue but parasitic plants growing on the host For a broom associated with witches see Besom For the nebula see Witch s Broom Nebula Witch s broom or witches broom is a deformity in a woody plant typically a tree where the natural structure of the plant is changed A dense mass of shoots grows from a single point with the resulting structure resembling a broom or a bird s nest It is sometimes caused by pathogens Witch s brooms on downy birch caused by the fungus Taphrina betulinaWitch s broom on a white pine Witch s broom in Yamaska National Park QCDiseases with symptoms of witches broom caused by phytoplasmas or basidiomycetes are economically important in a number of crop plants including the cocoa tree Theobroma cacao 1 jujube Ziziphus jujuba 2 and the timber tree Melia azedarach 3 Contents 1 Causes 2 Ecological role 3 See also 4 References 5 External linksCauses editA tree s characteristic shape or habit is in part the product of auxins hormones which control the growth of secondary apices The growth of an offshoot is limited by the auxin while that of the parent branch is not In cases of witch s broom the normal hierarchy of buds is interrupted and apices grow indiscriminately This can be caused by cytokinin a phytohormone which interferes with growth regulation The phenomenon can also be caused by other organisms including fungi oomycetes insects mites nematodes phytoplasmas and viruses 4 The broom growths may last for many years typically for the life of the host plant If twigs of witch s brooms are grafted onto normal rootstocks freak trees result showing that the attacking organism has changed the inherited growth pattern of the twigs 4 Ecological role editWitches brooms provide nesting habitat for birds and mammals such as the northern flying squirrel which nests in them 5 6 See also editPlant development buds and shoots atypical shoot development Epicormic shoot a shoot that develops from buds under the bark Forest pathology Longan witches broom associated virus Melampsora can cause different kinds of witch s brooms Moniliophthora perniciosa cause of witch s broom disease in cacao Phyllody a related plant growth abnormality affecting flowersReferences edit Purdy L H Schmidt R A 1996 Status Of Cacao Witches Broom Biology Epidemiology and Management Annual Review of Phytopathology 34 1 573 594 doi 10 1146 annurev phyto 34 1 573 PMID 15012557 Li Yun Wang Yu Tian Yanting amp Sun Haoyuan 2001 Advances in Tissue Culture and Eliminating of the Pathogeny of Witch Broom Disease MLO of Chinese Jujube a href Template Cite journal html title Template Cite journal cite journal a Cite journal requires journal help Gomez G G Conci L R Ducasse D A Nome S F 1996 Purification of the Phytoplasma Associated with China tree Melia azedarach L Decline and the Production of a Polyclonal Antiserum for its Detection Journal of Phytopathology 144 9 10 473 477 doi 10 1111 j 1439 0434 1996 tb00327 x a b Book of the British Countryside Pub London Drive Publications 1973 p 519 Mowry Robert A 2008 Northern Flying Squirrel PDF Alaska Department of Fish and Game Retrieved 2 June 2020 Paragi Thomas Rodman Sue 2020 Maintaining wildlife habitat in the boreal forest of Alaska PDF Alaska Department of Fish and Game pp 18 19 Retrieved 2 June 2020 External links edit nbsp Media related to Witch s broom at Wikimedia Commons Witches Broom at BBC h2g2 Fir and spruce broom Retrieved from https en wikipedia org w index php title Witch 27s broom amp oldid 1165228783, wikipedia, wiki, book, books, library,
