Category Archives: galls

Manzanita Leaf Gall Aphid

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In my previous post (see “Manzanita Leaf Fungus” on 08-20-2019), I discussed a manzanita (Arctosstaphylos ssp) gall caused by a fungus. An aphid, the manzanita leaf gall aphid (Tamalia coweni), also induces galls on manzanita shrubs. T coweni has an … Continue reading

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Manzanita Leaf Fungus

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There are more than 50 species of manzanita (Arctostaphylos ssp) in California alone. Two agents induce galls in manzanita species. Exobasidium vaccinii, a fungus, is one of these agents. E vaccinii induces swollen, convex, bright red galls on the dorsal … Continue reading

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Prunus Witches’ Broom

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  Continuing on the bitter cherry (Prunus emarginata) theme: The yeast-like sac fungus Taphrina confusa induces witches’ brooms on several Prunus species. Although the western choke cherry (P virginiana) and Sierra plum (P subcordata) are most often infected, Leonard and … Continue reading

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Oak Apple Gall

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There are over 150 species cynipid wasps that induce galls on California oaks. Barely the size of fruit flies, these wasps cause some of the most exotic plant galls displaying a variety of shapes (conical, spherical, stalked, disc-shaped, spiny, etc.) … Continue reading

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Red Cone Gall

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There are over 800 species of cynipid wasps, most of which use oak trees as their egg-laying sites. The red cone gall is induced by the cynipid wasp Andricus kingi. Red cone galls occur on the leaves of blue, OregonĀ  … Continue reading

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Hairy Gall Wasp

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Canyon live oaks (Quercus chrysolepis) are plentiful on Spring Hill (a “satellite” volcanic cone) at the base of Mount Shasta (Shasta County CA). When young, the evergreen, leathery leaves have spiny margins while older leaves are usually entire. Both leaf … Continue reading

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Willow Stem Galls

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The second gall Leonard and I found on willows along the Lower Hat Creek Trail (Shasta County CA) is the willow stem gall. I discussed the willow rosette galls that infect leaf buds in my last post (“Willow Rosette Gall” … Continue reading

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