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Remarks (public):For a complete description including images see www.cababstractsplus.org/dfb 
Remarks (internal):Clearly distinguished from all other species of Verticillium by the orange-yellow colour of the first formed prostrate hyphae and the production of both chlamydospores and microsclerotia.
 
Description type:Non-original description 
Description:Verticillium tricorpus Isaac, Trans. Br. mycol. Soc. 36: 194, 1953.
Cultures growing rapidly on potato-textrose agar and malt agar at 23°C, the prostrate hyphae first produced orange-yellow and appearing deep golden-yellow in reverse, becoming blackish below after 2-3 weeks. Mycelium flocculose, not densely compacted, the orange-yellow prostrate hyphae 2-3 µm diam., containing conspicuous oil globules; after c. 1 week, white conidiophores are produced vertically from the orange-yellow mycelium predominate, these giving the whole colony a whitish appearance in 2-3 weeks; hyaline sectors arising very requently.Conidiophores abundant, more or less erect, hyaline, verticillately branched, 3-4 phialides arising at each node. Phialides variable in size, mainly 12-25 x 2-3 µm. Conidia produced singly at the apices of the phialides, ellipsoidal to irregularly sub-cylindrical, hyaline, 3,5-10 x 1,5-3,5 µm. Resting mycelium formed, dark brown to blackish, of regularly distinctly septate hyphae, individual cells often becoming swollen so that the whole appears torulose, 3,5-7 µm wide. Chlamydospores arising on thick hyaline or brownish hyphae, hyaline or pale brownish at first, becoming darker brown when mature, mostly 7,5-11 µm diam. Microsclerotia arising on the dark resting mycelium, torulose, consisting of swollen almost globular hyphal cells, very variable in shape, elongate to almost spherical, mostly 60-85 µm diam.
Hosts: On Lycopersicon esculentum. Also reported on Antirrhinum.
Disease: Wilt of tomato.
Geographical distribution: Britain, especially in the south; India
Physiological specialization: Unknown.
Transmission: Little appreciable spread by root contact between infected plants (Isaac, 1953).
Literature : Isaac, Trans. Br. mycol. Soc. 36: 180-195, 1953; Smith, N.Z. Jl agric. Res. 8: 450-478, 1965 (taxonomy).

 
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