Spermogonia and aecia unknown. Uredinia on abaxial leaf surface, scattered or aggregated in small groups on a lesion, subepidermal, becoming erumpent, surrounded by paraphyses. Paraphyses united at the base, strongly incurved, 21-43 µm long, wall 2.5-5.5 µm thick, both dorsally and ventrally;urediniospores obovoid, obovoid-ellipsoid or oblong-ellipsoid, 16-27 x 11-17 µm, wall 1.5 µm thick, almost colourless, evenly echinulate, with four or six germ pores in equatorial zone of the spore wall, rarely scattered. Telia also formed on the abaxial surface, crustose, orange-brown, becoming dark-brown to blackish-brown, often confluent, subepidermal, applanate;teliospores more or less randomly arranged in 3-4 layers, oblong or ellipsoid, angular, 13-28 x 6-15 µm, wall thin and colourless, upper wall 2 µm thick and pale-brown. Basidiospores reniform, 9.0-12.5. x 5.5-8.0 µm. For an additional description and illustration, see Ono (2000).
The undersides of Ampelopsis leaves should be examined for yellowish, powdery uredinia and/or crust-like, orange-brown to blackish-brown telia.
Similarities to Other Species/Conditions
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This fungus appears to be highly host-specific, being restricted to the genus Ampelopsis with only a few other possible hosts (Ono, 2000). Thus, correct identification of the host ensures the identification of this species within the genus Phakopsora.
P. ampelopsidis forms strongly incurved, evenly thick-walled (2.5-5.5 µm) paraphyses in the uredinium, subglobose to oblong teliospores randomly arranged (not in rows) and not with spores in the upper row longer, and kidney-shaped basidiospores, by which it can be distinguished from the morphologically similar Phakopsora vitis on Parthenocissus and Phakopsora euvitis on Vitis.
Related invasive species
- Phakopsora ampelopsidis
Related Farm Practice
- Groups
Related location
- Unknown
As currently defined (Ono, 2000), the rust fungus P. ampelopsidis is a pathogen of hosts in the genus Ampelopsis and perhaps in related genera in the Vitaceae, but not of the cultivated grapevine species of Vitis or the ornamental species in Parthenocissus. Plants in Ampelopsis occur in Asia from Japan to Turkey as well as in North America (USDA-ARS, 2009), but the rust is not known in Europe, and has not been reported on Ampelopsis in the Americas. Only in eastern Asia, where the medicinal uses of Ampelopsis species are being investigated (Kim et al., 2007;Zhang et al., 2008), is this rust a potential problem. It is most likely to be spread by aerial dispersal of urediniospores to nearer parts of Asia, where species in the host genus are distributed.