Short Pedicels Research Articles

Kuehneola species (Phragmidiaceae, Pucciniales) on Vitaceae plants

The type specimen of Uredo cissi-debilis on Cissus debilis from Cote d’Ivoire was found to bear aparaphysate telia, in which a chain of two to four teliospores was formed on a short pedicel. The teliospores were thin-walled and germinated in situ. Another fungus identified as U. cissi-debilis on Cayratia gracilis from Sierra Leone was also found to form teliospores similar to those of the Cissus rust fungus in paraphysate telia. The teliospore morphology and host relationships showed their taxonomic affinity to Kuehneola vitis on Ampelocissus latifolia distributed in South Asia. It was concluded that presence or absence of paraphyses in sori and spore morphology, in addition to the assumed host preference, distinguish between the three fungi. New names, K. cissi-debilis comb. nov. and K. deightonii sp. nov., were proposed for the Cissus fungus and the Cayratia fungus, respectively.

Arabidopsis BREVIPEDICELLUS interacts with the SWI2/SNF2 chromatin remodeling ATPase BRAHMA to regulate KNAT2 and KNAT6 expression in control of inflorescence architecture.

BREVIPEDICELLUS (BP or KNAT1), a class-I KNOTTED1-like homeobox (KNOX) transcription factor in Arabidopsis thaliana, contributes to shaping the normal inflorescence architecture through negatively regulating other two class-I KNOX genes, KNAT2 and KNAT6. However, the molecular mechanism of BP-mediated transcription regulation remains unclear. In this study, we showed that BP directly interacts with the SWI2/SNF2 chromatin remodeling ATPase BRAHMA (BRM) both in vitro and in vivo. Loss-of-function BRM mutants displayed inflorescence architecture defects, with clustered inflorescences, horizontally orientated pedicels, and short pedicels and internodes, a phenotype similar to the bp mutants. Furthermore, the transcript levels of KNAT2 and KNAT6 were elevated in brm-3, bp-9 and brm-3 bp-9 double mutants. Increased histone H3 lysine 4 tri-methylation (H3K4me3) levels were detected in brm-3, bp-9 and brm-3 bp-9 double mutants. Moreover, BRM and BP co-target to KNAT2 and KNAT6 genes, and BP is required for the binding of BRM to KNAT2 and KNAT6. Taken together, our results indicate that BP interacts with the chromatin remodeling factor BRM to regulate the expression of KNAT2 and KNAT6 in control of inflorescence architecture.

Freshwater Ascomycetes: Jahnula purpurea (Jahnulales, Dothideomycetes), a new species on submerged wood from Martinique Island, Lesser Antilles

Jahnula purpurea J.Fourn., Raja & Shearer, a new species in the Jahnulales (Dothideomycetes) collected from submerged wood in a freshwater river in Martinique Island, Lesser Antilles, is described and illustrated. The characteristic features of the new species are: globose to subglobose, brownish black ascomata with broad, golden brown, subtending hyphae which stain the underlying wood purple; a peridial wall composed of large pseudoparenchymatic cells, which are textura angularis to prismatica in surface view; sparsely septate pseudoparaphyses embedded in a gel matrix; clavate to obclavate asci with a short pedicel; brown, one-septate, ellipsoidal, rough-walled ascospores without a gelatinous sheath or appendages. Unfortunately, because limited material was available from the type collection, we were unable to obtain molecular data. Jahnula purpurea is distinct from all previously described species of Jahnula in its ability to stain the wood purple and in a combination of ascomal, ascus, and ascospore size and morphology.

Treatment of mange caused by Caparinia tripilis in native Korean wild hedgehogs (Erinaceus amurensis): a case report

Infestation of the Caparinia tripilis mite in native Korean wild hedgehogs ( Erinaceus amurensis ) is described in this report. Five hedgehogs, including two adult males and three adult females, were rescued from the wild and referred to the Animal Health Centre of the Seoul Zoo, Korea. They were exhibited after completing quarantine. After one year and two months of exhibition, all hedgehogs began scratching, developed powdery deposits around the ears, eyes, and cheeks, and showed loose spines, scurf, and scales on the dorsal lesions. One had pruritic dermatitis on the outer ears and upper chest that resulted from severe scratching using its hind leg claws. The motile powdery deposits around the ears and eyes were visible to the naked eye. Skin was scraped from the lesions and examined by microscopy to diagnose the causative agent. Numerous mites (300-400 μm body length) were observed with three long setae on the third pair of legs, short and unjointed pedicels, and bellshaped tarsal caruncles. Based on these morphological features, the mites were identified as the non-burrowing C. tripilis mite. Treatment was successful after initial administration of 0.4 mg/kg ivermectin s.c. and subsequent 0.5 mg/kg p.o., repeated 14 and 28 days after injection. This is the first description of a capariniosis case in the native Korean wild hedgehog E. amurensis .

Samaras of Ventilago (Rhamnaceae) from the upper Miocene of Lincang, Yunnan, China and their phytogeographic implications

AbstractThe genus Ventilago Gaertn. usually occurs in hot, dry, and low‐altitude tropical environments. The fossil record of this genus is meager, so its origin and geographic history are still poorly understood. We describe a fossil winged fruit species—Ventilago lincangensis K. N. Liu & S. P. Xie sp. nov. from the upper Miocene Bangmai Formation of Lincang city, Yunnan Province, China. The fossil conforms to the modern genus Ventilago in architecture of the prominent fruit wing including a prominent midvein, a set of minor longitudinally secondary veins extending the full length of the fruit and reticulate higher order venation. The elliptical fruit body at the base of the wing shows an equatorial rim and has a short pedicel. This is the first report of Ventilago fruits in China, and is significant for the investigation of the origin and evolutionary history of this genus.

THE GESNERIACEAE OF SULAWESI VI: THE SPECIES FROM MEKONGGA MTS. WITH A NEW SPECIES OF CYRTANDRA DESCRIBED

Field exploration of the flora of the Mekongga Mountainous area of Southeast Sulawesi was conducted from 2009 to 2011. Herbarium specimens collected during this exploration and additional collections from Herbarium Bogoriense (BO) included 21 species in nine genera of the family Gesneriaceae. These comprise one species of Aeschynanthus, four species of Agalmyla, one species of Codonoboea, seven species of Cyrtandra, one species of Epithema, three species of Monophyllaea, two species of Rhynchoglossum, one species of Rhynchotechum and one species of Stauranthera. Twelve of these species are consider-ed endemic to Sulawesi while the rest are known to occur on neighbouring islands or are more widely distributed. Monophyllaea merrilliana, previously known only from the Philippine Islands and Borneo, is newly recorded for Sulawesi. A new species of Cyrtandra collected in the Mekongga area, C. widjajae, which resembles C. gorontaloensis from North Sulawesi but differs in having shorter pedicels and curved rather than straight fruits, is described.

Phylogenetic analysis based on structural and combined analyses ofRhus s.s. (Anacardiaceae)

Structural data were combined with trnL-F and internal transcribed spacer sequences from other studies and with new sequences representing ten additional species to clarify the phylogenetic relationships of Rhus s.s. These data indicate that Rhus s.s and both subgenera, Rhus and Lobadium, are monophyletic. The genus Rhus is supported as monophyletic by the presence of red glandular hairs on the berries and inflorescence axis, cilia on the sepals and glands on the leaf blades. Subgenus Rhus can be identified by the presence of more than seven resin channels in the petiole, weakly percurrent tertiary veins and a type I vascular system in the mid-vein. Subgenus Lobadium is characterized by the presence of short bracteoles and pedicels. This subgenus is divided into four sections, Lobadium, Rhoeidium, Styphonia and Terebinthifolia. Section Lobadium has trifoliate leaves; section Rhoeidium is monotypic, including only Rhus microphylla; section Styphonia is supported by five synapomorphies, including an incomplete marginal vein, fibres in the petiole, a thick cuticle, two layers of palisade parenchyma and prismatic crystals in the mesophyll; and section Terebinthifolia has gelatinous xylary fibres in the petiole. Hypotheses about the evolutionary changes of these characters are presented based on the cladograms. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 176, 452–468.

First Report of Phytophthora hedraiandra Causing Rhododendron Dieback and Root Rot of Common Beech in the Czech Republic.

From 2010 to 2012, Phytophthora isolates were obtained from brownish diffusion leaf lesions usually up to 2 to 3 cm in diameter of Rhododendron caucasicum 'Cheer,' from withered twigs of Rhododendron sp. with blackish elongated lesions up to ~5 cm in length, and from rotten feeder roots of 2-year-old, chlorotic, wilting seedlings of Fagus sylvatica collected from ornamental and forest nurseries in three areas (central and eastern Bohemia and northern Moravia) in the Czech Republic. Isolates formed chrysanthemum-like to slightly stellate, appressed colonies with sparse aerial mycelium on V8 agar (V8A) plates at 20°C after 5 days, whereas on carrot agar (CA) plates the pattern was vague with no aerial mycelium. The cardinal growth temperatures were: min. 3°C, optimum 23 to 27°C, and max. 31°C. Radial growth was 5.7 to 6.6 mm/day at 20°C on V8A. The isolates were homothallic and produced colorless, smooth-walled, spherical oogonia with an average diameter 29.9 to 33.8 μm on CA. Oospores were aplerotic (avg. 26.4 to 29.3 μm), oospore wall was hyaline and averaged 1.3 to 1.7 μm thick, oospore wall index was 0.26 to 0.32. Paragynous or occasionally amphigynous antheridia averaged 13.4 to 15.0 × 10.9 to 12.5 μm (height × width). Sporangia were caducous, papillate, globose, spherical to ovoid, with short pedicels (avg. 2.1 to 2.6 μm) and averaged 30.9 to 41.5 × 25.5 to 30.6 μm, L:B ratio was 1.2 to 1.4. Chlamydospores were not observed. Morphological characters resembled those described for P. hedraiandra (1). The isolates were deposited in the collection of phytopathogenic oomycetes of RILOG Pruhonice and given accession nos. 450.11, 531.11, and 578.12. The isolates were sequenced for nuclear rDNA ITS region and partial Cox I gene. Obtained sequences were compared with sequences present in GenBank database using BLAST. The ITS sequences of all isolates (GenBank Accession Nos. KJ567081, 82, and 83) of overall length of 792 bp were identical to that of P. hedraiandra AY707987 (1). The Cox I sequences of overall length of 880 bp (KJ567084, 85, and 86) showed 99% homology (1 bp substitution) with AY769115 (1) and 100% identity with other Cox I sequences of P. hedraiandra, i.e., JN376067 (4) and EF174432 (3). Koch's postulates were confirmed by wound-inoculating of 3-year-old rhododendron and common beech plants (10 host plants per corresponding isolate). Rhododendron leaves were gently abraded near the midrib, whereas 5-mm-diameter bark plugs were removed from the beech collars. The inoculum (5-mm-diameter V8A plug with actively growing mycelium) was placed over wounds and sealed with Parafilm. Control plants were treated in the same manner with sterile agar plugs. Plants were maintained in a greenhouse at 22°C. All inoculated plants showed disease symptoms after 10 days of incubation; the lesions were up to 2 cm in rhododendron leaves and ~1 cm in beech collars. Control plants remained healthy. The pathogen was re-isolated from all infected plants. To our knowledge, this is the first report of P. hedraiandra in the Czech Republic. Besides it, the pathogen was found in southern and western Europe (Italy, Slovenia, Spain, the Netherlands) and in the United States (2).

Characterization of a Multiseeded (msd1) Mutant of Sorghum for Increasing Grain Yield

ABSTRACTSorghum [Sorghum bicolor (L.) Moench] has branched panicles with primary, secondary, and tertiary branches. These inflorescence branches are composed of a terminal triplet spikelet, consisting of one sessile (directly attached to the branch) and two pedicellate (spikelets attached to the branch through a short pedicel), followed by one or more spikelet pairs (one sessile and one pedicellate). In BTx623, and most sorghum lines, only the sessile spikelets can develop into seeds and the pedicellate spikelets, occasionally developing anthers, eventually abort. Here, we report the isolation and characterization of a stable multiseeded (msd1) mutant of sorghum (in BTx623 background, referred to as wild‐type [WT]) in which both sessile and pedicellate spikelets are fertile. In addition, this mutant displayed increased length and total number of primary and secondary inflorescence branches. Genetic analysis showed that this multiseeded mutation is a recessive trait. Pedicellate spikelets in msd1 mutants exhibited complete flower with functional ovary and anthers, of which 75 to 95% can develop into viable seeds. The individual msd1 seeds are smaller than WT; however, the results indicated that this reduction in seed weight can be compensated by the increase in seed number. The total seed weight per panicle in msd1 mutants was increased by 30 to 40% as compared to the WT. Further experiments are needed to demonstrate whether the msd1 mutation can increase grain yield under field conditions.

<b>Distribution and structural aspects of extrafloral nectaries in leaves of <i>Pyrostegia venusta</i> (Bignoniaceae)

Pyrostegia venusta (the orange trumpet or commoly called cipó-de-São-João in Brazil), a medicinal plant that grows with other plants, has an ecological importance due to the presence of nectaries on the leaves. The aim of this work was to study structural and histochemical aspects and the distribution of extrafloral nectaries (ENFs) in P. venusta leaves. Young leaves were collected, fixed and processed by usual techniques, and studied under light microscopy and scanning electron microscopy. Analyses showed that the extrafloral nectaries are dispersed throughout the leaf, with concentrations mainly in the basal third section. Nectaries lie in epidermal depressions and can be found in abaxial and adaxial leaf blades. Their morphology may be characterized macroscopically by achlorophyllous halos and microscopically as structures consisting of a short pedicel, oval multicellular head, covered by a thin cuticular layer with a secretory pole. Reducing sugars, neutral polysaccharides, proteins, starch and phenolic compounds were detected in extrafloral nectaries.

Taxonomy of Atlantic Central African orchids 2. A second species of the rare genus Distylodon (Orchidaceae, Angraecinae) collected in Cameroon

While conducting field inventories in South Cameroon, we collected two specimens of a new species that we considered to belong to the genus Angraecopsis. Afterwards, a careful examination of specimens housed at main herbaria, along with the nomenclatural types, allows us to place it in Distylodon, a monotypic genus previously known from East Africa. Distylodon sonkeanum Droissart, Stévart & P.J.Cribb, sp. nov. was collected in the lowland coastal forest of Atlantic Central Africa. It is known from a single locality in the surroundings of the Campo-Ma’an National Park. The species differs from D. comptum, by its several-flowered inflorescences, longer leaves and spur, and shorter pedicel and ovary. The species appears to be rare and is assessed as Critically Endangered [CR B2ab(iii)] according to IUCN Red List Categories and Criteria. New field investigations are required to attempt to find it in the low-elevation parts of the Campo-Ma’an National Park in Cameroon.

A new species of Coelogyne (Orchidaceae) from western Yunnan, China

A new species of Orchidaceae, Coelogyne pianmaensis, is described and illustrated from western Yunnan, China. Morphologically, it is similar to Coelogyne corymbosa, but differs from the latter by having dark brown eyelike blotches surrounded by brownish-yellow on lip, 1-veined obovate-oblong leaves, 7-veined oblong-lanceolate sepals, shorter pedicel and ovary, and 7-veined petals.

Ultra- and microstructure of the female reproductive system of Matsucoccus matsumurae

The ultra- and microstructure of the female reproductive system of Matsucoccus matsumurae was studied using light microscopy, scanning and transmission electron microscopy. The results revealed that the female reproductive system of M. matsumurae is composed of a pair of ovaries, a common oviduct, a pair of lateral oviducts, a spermatheca and two pairs of accessory glands. Each ovary is composed of approximately 50 telotrophic ovarioles that are devoid of terminal filaments. Each ovariole is subdivided into an apical tropharium, a vitellarium and a short pedicel connected to a lateral oviduct. The tropharium contains 8–10 trophocytes and two early previtellogenic oocytes termed arrested oocytes. The trophocytes degenerate after egg maturation, and the arrested oocytes are capable of further development. The vitellarium contains 3–6 oocytes of different developmental stages: previtellogenesis, vitellogenesis and choriogenesis. The surface of the vitellarium is rough and composed of a pattern of polygonal reticular formations with a center protuberance. The oocyte possesses numerous yolk spheres and lipid droplets, and is surrounded by a mono-layered follicular epithelium that becomes binucleate at the beginning of vitellogenesis. Accessory nuclei are observed in the peripheral ooplasm during vitellogenesis.

Localization and density of phoretic deutonymphs of the mite Uropoda orbicularis (Parasitiformes: Mesostigmata) on Aphodius beetles (Aphodiidae) affect pedicel length

The phoretic stage of Uropodina mites is a deutonymph with developed morphological adaptations for dispersal by insects. Phoretic deutonymphs are able to produce a pedicel, a stalk-like temporary attachment structure that connects the mite with the carrier. The aim of our study was to determine whether localization and density of phoretic deutonymphs on the carrier affect pedicel length. The study was conducted on a common phoretic mite—Uropoda orbicularis (Uropodina) and two aphodiid beetles—Aphodius prodromus and Aphodius distinctus. Our results show that pedicel length is influenced by the localization of deutonymphs on the body of the carrier. The longest pedicels are produced by deutonymphs attached to the upper part of elytra, whereas deutonymphs attached to femora and trochanters of the third pair of legs and the apex of elytra construct the shortest pedicels. In general, deutonymphs attached to more exposed parts of the carrier produce longer pedicels, whereas shorter pedicels are produced when deutonymphs are fixed to non-exposed parts of the carrier. A second factor influencing pedicel length is the density of attached deutonymphs. Mean pedicel length and deutonymph densities were highly correlated: higher deutonymph density leads to the formation of longer pedicels. The cause for this correlation is discussed, and we conclude that pedicel length variability can increase successful dispersal.

Reproductive biology of Pittosporum dasycaulon Miq., (Family Pittosporaceae) a rare medicinal tree endemic to Western Ghats.

BackgroundFor successful cultivation and conservation of plants a detailed knowledge of their reproductive biology is required. The reproductive features of trees are important to determine the diversity patterns and community structure of tropical forests. The present study on reproductive biology of Pittosporum dasycaulon, a rare medicinal tree, was conducted in the shola forests of Vaghamon hills, one of the foot hills of Southern Western Ghats of India from 2008–2011.ResultsThe plant flowers profusely during February to April. Inflorescence is a raceme and the total number of flowers per inflorescence varies from 96–217. The flowers are comparatively small, hermaphrodite, short pedicellate, complete, zygomorphic, pentamerous, polypetalous, hypogynous and light cream in colour with an average length of 1.14 cm. Anthesis started at 08.30 h and the flowers were completely opened at approximately 09.30 h followed by anther deshiscence at 10.00-11.30 h. The pollen grains were trizonocolpate with 45 ± 5.6 μm in size. Acetocarmine staining showed 66 ± 6% fertile pollen at the time of anther dehiscence. The number of pollen grains in an anther is 5246 ± 845 and per flower is 26230 ± 1021. The stigma is wet, non-papillate, capitate and contains a thin film of exudates under the light microscope. The superior ovary is densely covered with papillate hairs and containing 3–8 ovules. The important floral visitors include bees and butterflies. The plant is self-incompatible and an out crosser. Fruit set under open-pollination was poor (24%) with 58.3% fruits having seeds inside. There was no fruit set in manually self pollinated flowers while over 57% of the cross pollinated flowers set fruits.ConclusionsOur study presents a detailed account on reproductive biology of this medicinal tree which may help in the conservation and genetic improvement of this particular taxa.Electronic supplementary materialThe online version of this article (doi:10.1186/1999-3110-55-15) contains supplementary material, which is available to authorized users.

First Report of Citrus Root Rot Caused by Phytophthora palmivora in Egypt.

During spring-summer 2009, a survey was conducted to determine the species of Phytophthora present in citrus nurseries in Egypt. A total of 300 samples of soil and fibrous roots were collected from the rhizosphere of symptomatic Volkameriana lemon (Citrus volkameriana Tan. & Pasq.) plants growing in Delta (Benha-Qalyubia) and a desert (Cairo/Alexandria desert road) citrus nurseries. Plants showed various symptoms. Canopies of affected plants showed few and yellowish leaves, a general stunted growth, no new vegetation, and sometimes sudden desiccation; the root system showed few dark brown feeder roots, no new yellow-white apexes, and a fibrous appearance of the rootlets due to disintegration of the cortical bark but not of the xylem. Collected rootlets and soil were plated in Petri dishes containing a selective medium for the oomycete Phytophthora (2) and incubated for 3 to 6 days at 19 ± 1°C as described by Ippolito et al. (1). Pure cultures were obtained by single-hypha transfers and the isolates were identified as Phytophthora palmivora (Butler) Butler on the basis of morphological and cultural characteristics (3). Isolates formed stoloniferous colonies on potato dextrose agar (PDA) and grew between 10 and 30°C, with the optimum at 25°C. On V8 juice agar, they showed a highly fluffy pattern and produced terminal and intercalary globose chlamydospores. Sporangia were papillate, elliptical (45 to 51 × 29 to 35 μm; length/breadth ratio of 1.3:1.8), and were caducous with short pedicel. All isolates were A2 mating type, forming spherical oogonia and amphigynous antheridia in dual cultures with reference P. palmivora isolate of A1 mating type. Identification of the isolates was further confirmed by amplification and sequencing of the internal transcribed spacer (ITS) region using the universal primers ITS4 and ITS6. BLASTn analysis of ITS sequences (GenBank Accession No. HE583183) showed 99% homology with P. palmivora isolates available in GenBank. Pathogenicity tests for P. palmivora were conducted by inoculating three groups of ten 6-month-old Volkameriana lemon plants, transplanted into 1.4 liter pots with growing medium artificially inoculated at the rate of 1% (v/v) of P. palmivora inoculum produced according to Yaseen (4). Ten uninoculated plants served as a control. Two months after the inoculation, plants were analyzed for canopy symptoms and the presence of pathogen in feeder roots. More than 50% of inoculated plants showed foliage symptoms and extensive decay of feeder roots. Colonies of Phytophthora were recovered from necrotic rootlets and identified as P. palmivora, fulfilling Koch's postulates. To the best of our knowledge, this is the first report of P. palmivora as a pathogen to citrus plants in the Egyptian nurseries. P. palmivora should be considered a potential threat to the Egyptian citrus industry since it may negatively influence the nurseries and orchards production in the future.

A New Species ofMaytenus(Celastraceae) from Bahia, Brazil, and Neotypification ofMaytenus boaria

A new species of Maytenus is described and illustrated. Maytenus psammopliila is apparently endemic to the state of Bahia, where it grows in the sandy soils of dunes in ‘caatinga’ physiognomy. This species is recognized by its cylindrical or slightly flattened young twigs with lenticels, small ovate coriaceous leaves and inflorescences, reduced cymes with short pedicellate flowers. It resembles M. rigida, which also occurs in the same area but differs from it by its margins with no thorns and by its inflorescences (cymes vs. fascicles in M. rigida). Neotypification of M. boaria is here proposed, this neotypification is important because this species is the type species of the genus Maytenus.

<I>Barjonia furlanii</I> (Apocynaceae, Asclepiadoideae), a New Species from the State of Minas Gerais, Brazil, and a Key to Genus

Abstract This paper provides descriptions and illustrations of a new species, Barjonia furlanii (Asclepiadoideae, Apocynaceae), from Serra da Canastra National Park, in the state of Minas Gerais, Brazil. This species is similar to B. laxa, especially in its frondose thyreoid inflorescence, compound corona, and linear leaves. It is, however, distinguished from B. laxa by internodes (up to 4 cm long), peduncles (4.2–5mm long) and much shorter pedicels (4–6 mm long), erect leaves, attenuated at the base, and partial inflorescences that alternate with 2–4 flowers. B. furlanii is proposed for Endangered status under IUCN guidelines (EN B2abiii), and a key to all Barjonia species is included in this study.

New Species of <I>Peperomia</I> (Piperaceae) from Brazil

Abstract Two new species of Peperomia from Brazil are described and illustrated based on morphological traits: Peperomia diamantinensis from the state of Bahia and Peperomia cruzeirensis from the state of Acre. Peperomia diamantinensis is very similar to Peperomia obtusifolia and Peperomia magnoliifolia, differing from the latter in the acute leaf apex and the short internodes. Peperomia cruzeirensis is similar to Peperomia elongata Kunth, but differs from the latter in the short pedicel of the fruits, and the petiole without two rows of trichomes. Discussions on taxonomy, geographic distribution, conservation status and habitat are provided, as well as identification keys to the Brazilian species of the Oxyrhynchum and Leptorhynchum clades.

First Report of Late Blight Caused by Phytophthora infestans Clonal Lineage US-23 on Tomato and Potato in Wisconsin, United States.

Tomato (Solanum lycopersicum) and potato (S. tuberosum) crops are grown on over 67,000 acres (27,114 ha) in Wisconsin annually. Late blight, caused by Phytophthora infestans (Mont.) deBary, is a potentially devastating disease that affects tomato and potato crops in Wisconsin every few years when inoculum is introduced and weather conditions favor disease. Incidence and severity of late blight are highly variable in these few years due to differences in pathogen clonal lineages, their timing and means of introduction, and weather conditions. Prevention of this disease through preventative application of fungicides can cost producers millions of dollars per year in additional chemical, fuel, and labor expenses. In 2009, late blight caused by P. infestans clonal lineage US-23 was observed on potato very late in the season in Vernon County, southwestern Wisconsin, in very low incidence and severity. In 2010, US-23 again appeared but on tomato in two southeastern Wisconsin counties, Waukesha and Ozaukee, again in low incidence and severity. Clonal lineages of P. infestans documented in Wisconsin in previous epidemics included US-8 in the mid-1990s and US-1 in the 1970s. Populations of P. infestans in the United States have recently undergone significant genetic change, resulting in isolates with unique clonal lineages and epidemiological characteristics (1). Foliar symptoms included water-soaked to dark brown circular lesions with pale green haloes accompanied by white pathogen sporulation. On tomato fruit, lesions were firm, sunken, and brown. Isolates of P. infestans were generated from field-infected tomato and potato foliar and fruit tissues collected by the authors and professional crop consultants. In initial pathogen confirmation analysis in 2009, three isolates of P. infestans were generated from one potato plant exhibiting multiple lesions from one of eight fields tested by placing infected leaf excisions onto Rye A agar amended with rifampicin and ampicillin. Axenic, single zoospore-derived cultures of isolates were generated from parent cultures and maintained on Rye A agar for further characterization. In 2010, three US-23 isolates were recovered from three locations (two counties), out of 20 fields tested. Mycelium was coenocytic with hyphal diameter of 5 to 8 μm (n = 50). Sporangia were limoniform or ovoid, semi to fully papillate, caducous, had short pedicels, and were 26.16 μm high × 18.17 μm wide (n = 50). The average length/width ratio was 1.42. Allozyme banding patterns at the glucose-6-phosphate isomerase (Gpi) locus indicated a 100/100 profile, consistent with the US-23 clonal lineage (3) Mating type assays confirmed the isolates to be A1 and in vitro intermediate mefenoxam sensitivity was observed (4). Genomic DNA was extracted with a phenol/chloroform/isoamyl alcohol solution and RFLP analysis was performed using the RG-57 probe on a representative isolate and resulted in banding patterns consistent with US-23 (2,3). The P. infestans clonal lineage US-23 was present in epidemics in 2009 and 2010 in the United States. Disease symptoms associated with US-23 were observed exclusively on potato in 2009 and on tomato in 2010 in Wisconsin. To our knowledge, this is the first report of P. infestans clonal lineage US-23 causing late blight on tomato and potato in Wisconsin and represents a change in the composition of the pathogen population from previous epidemic years.