steve clements1
Witches' Broom
Ramsley Moor is a good spot for Witches' Broom or Birch Besom, which is often assumed by field mycologists to be a gall induced by Taphrina betulina. Sorby Fungus Group has 30 Taphrina records on Birch, three of which are named as Taphrina betulae (which seems to be a leaf spot rather than a Witches' Broom).
However, I haven’t ever confirmed the fungus microscopically so I don’t record it any more as according to the two entries below there can be many causes of this deformity – not just the fungus.
From Wikipedia - Witch's broom can be caused by cytokinin, a phytohormone, interfering with an auxin-regulated bud. Usually auxin would keep the secondary, tertiary, and so on apexes from growing too much, but cytokinin releases them from this control, causing these apexes to grow into witch's brooms.
Witch's broom may be caused by many different types of organisms, including fungi, oomycetes, insects, mistletoe, dwarf mistletoes, mites, nematodes, phytoplasmas orviruses.[4] The broom growths may last for many years, typically for the life of the host plant. Human activity is sometimes behind the introduction of these organisms; for example by failing to observe hygienic practice and thereby infecting the tree with the causative organism, or by pruning a tree improperly, and thereby weakening it
From Encyclopaedia Britannica - witches’-broom, symptom of plant disease that occurs as an abnormal brushlike cluster of dwarfed weak shoots arising at or near the same point; twigs and branches of woody plants may die back. There are numerous causes, including rust (Gymnosporangium and Pucciniastrum); Apiosporina, Exobasidium, and Taphrina fungi; mites; insects; viruses; mycoplasmas; bacteria; and mistletoes. Susceptible plants include alder, alfalfa, Amelanchier, birch, California buckeye, Chamaecyparis, cherry, cherry laurel, elm, eucalyptus, fir, hackberry, Holodiscus (ocean spray), honey locust, juniper and red cedar, manzanita, mountain heath, mulberry, oak, potato, rhododendron, rose, sophora, spruce, and strawberry.
Witches' Broom
Ramsley Moor is a good spot for Witches' Broom or Birch Besom, which is often assumed by field mycologists to be a gall induced by Taphrina betulina. Sorby Fungus Group has 30 Taphrina records on Birch, three of which are named as Taphrina betulae (which seems to be a leaf spot rather than a Witches' Broom).
However, I haven’t ever confirmed the fungus microscopically so I don’t record it any more as according to the two entries below there can be many causes of this deformity – not just the fungus.
From Wikipedia - Witch's broom can be caused by cytokinin, a phytohormone, interfering with an auxin-regulated bud. Usually auxin would keep the secondary, tertiary, and so on apexes from growing too much, but cytokinin releases them from this control, causing these apexes to grow into witch's brooms.
Witch's broom may be caused by many different types of organisms, including fungi, oomycetes, insects, mistletoe, dwarf mistletoes, mites, nematodes, phytoplasmas orviruses.[4] The broom growths may last for many years, typically for the life of the host plant. Human activity is sometimes behind the introduction of these organisms; for example by failing to observe hygienic practice and thereby infecting the tree with the causative organism, or by pruning a tree improperly, and thereby weakening it
From Encyclopaedia Britannica - witches’-broom, symptom of plant disease that occurs as an abnormal brushlike cluster of dwarfed weak shoots arising at or near the same point; twigs and branches of woody plants may die back. There are numerous causes, including rust (Gymnosporangium and Pucciniastrum); Apiosporina, Exobasidium, and Taphrina fungi; mites; insects; viruses; mycoplasmas; bacteria; and mistletoes. Susceptible plants include alder, alfalfa, Amelanchier, birch, California buckeye, Chamaecyparis, cherry, cherry laurel, elm, eucalyptus, fir, hackberry, Holodiscus (ocean spray), honey locust, juniper and red cedar, manzanita, mountain heath, mulberry, oak, potato, rhododendron, rose, sophora, spruce, and strawberry.