Gerwasia pittieriana (Henn.) León-Gall. & Cummins 1981

Micropuccinia pittieriana (P. Henn.) Arthur & Jackson
Puccinia Pittieriana P. Henn. Hedwigia 43: 147. 1904.
Uredo Pittieri P. Henn.; Pittier, PI. Usual. Costa Rica 69, 122, hyponym. 1908.
Pycnia unknown, probabiy not formed

Spirechina pittieriana (P. Henn.) Arthur
Uromyces Pittierianus P. Henn. Hedwigia Beibl. 41 : 101. 1902. Uredo ochraceo-flava P. Henn. Redwigia Beibl. 41 : 101. 1902.
Pycnia epiphyllous, few in crowded groups, soon surrounded by primary uredinia, prominent, honey-yellow becoming golden-brown, subcuticular extending into the epidermal cells beneath, mammilloid, about 145 /^ broad by 80 ;W high.
Uredinia at first (primary) epiphyllous, few surrounding the pycnia, not crowded, groups 1-3 mm. across, sori irregularly roundish, 0.1-0.3 mm. across, at first bullate, ruptured irregularly, pulverulent, dirty-white when old, rupturing epidermis overarching and moderately conspicuous; urediniospores ellipsoid or obovoid, 18-21 by 29-43 /i; wall nearly colorless, rather thick, 3-4//, slightly thicker above, spinosely and sparsely echinulate, more pronounced at apex with spines arranged in a crown sometimes more pronounced at base forming a tuft directed downward, the pores obscure ; secondary form not well shown, probably hypophyllous with small sori.
III. Telia hypophyllous, scattered, often more numerous along the edges of the leaf, small, 0.3-0.8 mm., early naked, pulverulent, white, ruptured epidermis inconspicuous; teliospores fusiform or irregularly cylindroid, 15-21 by 40-75 /i, usually narrowed toward both ends ; wall colorless, uniformly thin, 1 /U or less, smooth ; pedicel colorless, half length of spore or less, 6-8// in diameter.
On Rosaceae :
Rubus adenotrichos^Q^^Kih.t,,Q.os.2.^^2.. „ . _, ^ ^ ^ ^ ^. ,,„.
Type locality : Hacienda Belmira near Santa Maria de Dota, Costa Rica, on ''Rubus sp.," determined by W. O. Focke to be R. adenotrichos.
Distribution : Known only from the type locality.

on Rubus sp. Panama, Chiriqui Province, Boquete, 8°46.691N, 82°25.968'W, 26 Nov. 2004, leg. J.R. Hernandez and M. Vega Rios 2004-123, II (BPI 864110).

G. pittieriana was reported from Costa Rica and Mexico on species of Rubus (Farr et al. 2004). This is the first report of G. pittieriana from Panama.

Puccinia pittieriana (syn. Gerwasia pittieriana) is a species of rust fungus. It is a plant pathogen which infects agricultural crops such as potato and tomato. Its common names include common potato rust and common potato and tomato rust.

This fungus was first made known to science in 1904 when it was collected from potatoes in cultivation on the slopes of Irazú Volcano in Costa Rica. It was later found on wild potato species such as Solanum demissum and on tomato crops. It is now known from Central and South America and from Mexico. Its known hosts now include many wild and cultivated species of Solanum. This is the only rust fungus that infects tomatoes.

Fungal infection manifests as greenish white spots a few millimeters wide on the undersides of a plant's leaves. The upper surfaces of the leaves may be dimpled as the lesions penetrate the blades. The lesions turn whitish with red to brown centers. The lesions spread across the leaf, which then dies and falls. Lesions can also form on the petioles, stems, flowers, and fruits.

The fungal spores are borne on the wind and infect plants when the plant surface is moist and the average temperature is around 10 °C. Symptoms appear in about two weeks and the lesions are largest by 20 to 25 days after infection by spores.

Several potato cultivars are resistant to the rust.