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Some new records of powdery mildew fungi from Argentina.

2001; Verlag Ferdinand Berger & Söhne; Volume: 53; Issue: 1 Linguagem: Inglês

0082-0598

Uwe Braun, M Kiehr, R. Delhey,

Yeasts and Rust Fungi Studies

Delhey, r., Braun, u. & Kiehr, M. 2003: Some new records of powdery mildew fungi from Argentina (2). Schlechtendalia 10: 79–90. The new species Oidium jacarandigena is described. Erysiphe rayssiae, Golovinomyces artemisiae, G. sordidus and Podosphaera plantaginis are new to Argentina and South America. 13 new hosts for various powdery mildew species are recorded: Blumeria graminis Bromus brevis; Erysiphe cruciferarum Lepidium bonariense; E. howeana Oenothera mollissima; E. trifolii Lathyrus tomentosus; Golovinomyces cichoracearum Noticastrum diffusum, Solidago chilensis; Golovinomyces cichoracearum var. latisporus Parthenium hysterophorus; G. sordidus Plantago berroi, P. tomentosa; Leveillula taurica Asclepias mellodora; Neoerysiphe cumminsiana Bidens subalternans; Podosphaera clandestina Pyracantha atalantoides; P. xanthii Cucurbita maxima ssp. andreana. Some other hosts are known from other countries, but they are new to Argentina: Blumeria graminis Avena barbata, Elytrigia repens; E. polygoni Rumex crispus; G. biocellatus Melissa officinalis, Mentha rotundifolia, Salvia verbenaca; G. cichoracearum Gerbera jamesonii, Lactuca sativa, L. serriola, Ambrosia tenuifolia; G. orontii Datura ferox, Viola tricolor; Podosphaera aphanis Rubus idaeus; P. clandestina Cydonia oblonga, Spiraea cantoniensis; P. pannosa Eucalyptus camaldulensis; P. plantaginis Plantago lanceolata. A total of 57 host-fungus combinations is presented, 17 with native host species and 40 with introduced host species. In only two cases the teleomorph state has been observed. Zusammenfassung: Delhey, r., Braun, u. & Kiehr, M. 2003: Einige neue Angaben von Mehltaupilzen aus Argentinien (2). Schlechtendalia 10: 79–90. Die neue Art Oidium jacarandigena wird beschrieben. Erysiphe rayssiae, Golovinomyces artemisiae, G. sordidus und Podosphaera plantaginis sind neu fur Argentinien und Sudamerika insgesamt. Weiterhin wird uber neue Wirte fur verschiedene Mehltauarten berichtet: Blumeria graminis Bromus brevis; Erysiphe cruciferarum Lepidium bonariense; E. howeana Oenothera mollissima; E. trifolii Lathyrus tomentosus; Golovinomyces cichoracearum Noticastrum diffusum, Solidago chilensis; Golovinomyces cichoracearum var. latisporus Parthenium hysterophorus; G. sordidus Plantago berroi, P. tomentosa; Leveillula taurica Asclepias mellodora; Neoerysiphe cumminsiana Bidens subalternans; Podosphaera clandestina Pyracantha atalantoides; P. xanthii Cucurbita maxima ssp. andreana. Einige andere Wirtspflanzen sind aus anderen Landern schon bekannt, aber werden fur Argentinien erstmals angegeben: Blumeria graminis Avena barbata, Elytrigia repens; E. polygoni Rumex crispus; G. biocellatus Melissa officinalis, Mentha rotundifolia, Salvia verbenaca; G. cichoracearum Gerbera jamesonii, Lactuca sativa, L. serriola, Ambrosia tenuifolia; G. orontii Datura ferox, Viola tricolor; Podosphaera aphanis Rubus idaeus; P. clandestina Cydonia oblonga, Spiraea cantoniensis; P. pannosa Eucalyptus camaldulensis; P. plantaginis Plantago lanceolata. Insgesamt werden 57 Kombinationen von Wirten und Pilzen aufgezahlt, davon 17 mit heimischen Wirten und 40 mit Wirten, die nicht heimisch sind. In nur zwei Fallen konnte die Hauptfruchtform gefunden werden. 80 Schlechtendalia 10 (2003) This is a second contribution, after Braun et al. (2000), on powdery mildew fungi of the southern Pampean region (S of Buenos Aires and adjacent parts of La Pampa and Rio Negro provinces), Argentina. This region, as well as many others in Argentina, is still insufficiently known with respect to the occurrence and distribution of Erysiphales. On the contrary, the Andean parts of Patagonia and Tierra del Fuego as well as the northeastern provinces have been studied more thoroughly, mainly due to the efforts of M. Havrylenko in the former and M.A. Mazzanti, M.G. Cabrera and R.E. Alvarez in the latter region (for literature compilation see Delhey & Braun 2001). The region covered by the present contribution phytogeographically includes parts of the “Provincia Pampeana” and the “Provincia Espinal” of CaBrera (1971). Especially the former is heavily modified by agriculture, animal husbandry and urbanization; introduced crops, ornamentals, forest trees, weeds and ruderals in many places have replaced the native vegetation. The collections described are deposited in BB (Universidad Nacional del Sur, Departamento de Biologia, Herbarium, Bahia Blanca, Argentina) and HAL (Martin-LutherUniversitat, FB. Biologie, Institut fur Geobotanik und Botanischer Garten, Herbarium, Halle/Saale, Germany). New species Oidium [subgen. Pseudoidium] jacarandigena sp. nov. Fig. 1 Mycelium amphigenum, externum, effusum, tenellum. Hyphae superficiales, sparse ramosae, 2–5 μm latae, hyalinae, leves, septatae, tenuitunicatae; appressoriis singularis vel binis, oppositis, mammaeformibus vel lobatis, 3–6 μm latis. Conidiophora solitaria, ex hyphis superficialibus oriunda, erecta, recta vel raro leniter curvata, cellula basali cylindrica, 20–25 × 6 –9 μm, et cellulis sequentibus, 1–2, brevioribus vel subaequalis. Conidia solitaria vel catenata, obovoidea, ellipsoidea –cylindrica, doliiformes, utrimque rotundata vel subtruncata, (20–)25–35(–38) × 10–18 μm, longit./latid. 1.5–3.2, hyalina, tenuitunicata. Holotype: on Jacaranda mimosifolia D. Don (Bignoniaceae), Argentina, Bahia Blanca, 20 Jul. 2003, R. Delhey 1745 (HAL 1747); leg. R. Delhey. Paratype: on Jacaranda mimosifolia (Bignoniaceae), Argentina, Bahia Blanca, 4 Sept. 2002, R. Delhey 1695 (HAL 1748); leg. M. Zazzetta. Mycelium amphigenous, external, effuse, delicate. Hyphae superficial, sparingly branched, 2–5 μm wide, hyaline, smooth, septate, thin-walled, appressoria solitary or in opposite pairs, nipple-shaped to lobed, 3–6 μm wide. Conidiophores solitary, arising from superficial hyphae, erect, straight or rarely slightly curved, basal cells (foot-cells) cylindrical, 20–25 × 6–9 μm, followed by 1–2 shorter cells or cells of about the same length. Conidia solitary or often adhering in loose chains, primary conidia obovoid, apex broadly rounded, base subtruncate, secondary conidia ellipsoid –cylindrical, doliiform, ends rounded to subtruncate, (20–)25–35(–38) × 10–18 μm, l/w ratio 1.5–3.2, hyaline, thin-walled, fresh conidia with oil-drops. Delhey et al.: Some new records of powdery mildew fungi from Argentina (2) 81 Notes: Some conidia with terminal or subterminal, short, straight to flexuous germ tubes, apex slightly swollen or lobed, have been observed. There is no comparable species of Oidium [Pseudoidium] on hosts of the Bignoniaceae. The conidia of the anamorphs of Erysiphe catalpae S. Simonyan (on Catalpa spp.), Erysiphe elevata (Burrill) U. Braun & S. Takam. (on Catalpa spp.) and E. peckii (U. Braun) U. Braun & S. Takam. (on Campsis radicans) [Braun 1987a] are consistently formed singly. Oidium jacarandigena is morphologically close to O. neolycopersici L. Kiss (Kiss et al. 2001), a species of nearly circumglobal distribution wherever tomatoes are grown, which is also known from the Pampean region of Argentina. The latter species is a species of Oidium subgen. Pseudoidium with solitary conidia, but also formed in short chains under humid conditions. However, it differs from O. jacarandigena in having much longer conidiophores, 30–75 μm, occasionally somewhat inflated in the middle and constricted at the base. Obs.: On small potted plants held indoors; the affected plants lost all the infected leaves which were replaced by new apparently uninfected ones which in turn became infected the following year. Many adult Jacaranda trees growing in the city of Bahia Blanca have been checked during different seasons but powdery mildew infections have never been observed. The native range of the highly appreciated and widely cultivated Jacaranda tree includes the NW of Argentina, Bolivia and Brazil. Powdery mildews have not been reported before on this species. As O. jacarandigena has the potential to weaken young seedling plants it might be of economic importance in nurseries. Fig. 1: Oidium jacarandigena sp. nov., conidia, conidiophores, appressoria; scale = 20 μm; U. Braun del. 82 Schlechtendalia 10 (2003)