In 2008 and 2009, necrotic bark lesions at the root collar and lower stem associated with root rot, reduced growth, and wilting were observed on container-grown common box (Buxus sempervirens L.), lavender (Lavandula angustifolia Mill. ‘Hidcote’), and Port-Orford-cedar (Chamaecyparis lawsoniana (A. Murray) Parl. ‘Columnaris’) in three ornamental nurseries in western Hungary. Number of affected plants ranged from approximately 100 (Port-Orford-cedar) to 250 (lavender). Isolations from necrotic root collars of each host plant species yielded four Phytophthora isolates developing uniform colonies on carrot agar with a maximum growth temperature of 35 to 36°C. The isolates were homothallic with smooth-walled oogonia (32.2 ± 2.3 to 35.9 ± 3.5 μm), aplerotic oospores (27.5 ± 1.8 to 32.1 ± 3.1 μm) and both amphigynous and paragynous antheridia, and produced chlamydospores (25.8 ± 3.9 to 29.1 ± 5.2 μm) and papillate sporangia (35.2 ± 2.5 to 43.5 ± 5.6 μm long and 27.6 ± 2.2 to 32.0 ± 3.8 μm wide), mostly obpyriform to nearly spherical or rarely distorted with two or three apices. In spring water, sporangia were both caducous with short pedicel and non-caducous. Multiplex ITS-PCR assay of DNA from all isolates, using primers specific for P. nicotianae (NICF1 and NICR2.1) and P. cactorum (CACTF1 and CACTR1) (1), amplified DNA fragments of the expected size for each Phytophthora species. In addition, isoenzyme analysis revealed a characteristic banding pattern of one heterodimer and two homodimer bands at both loci of the dimeric enzyme malate dehydrogenase. These bands comigrated with those of P. × pelgrandis (Gerlach et al.) (CBS 123385) and isolate PD 93/1339 (courtesy of W. A. Man in ‘t Veld), two natural hybrid strains of P. nicotianae and P. cactorum (2,3), proving that our four isolates can be referred to as this interspecific hybrid. Pathogenicity was tested on 1- or 3-year-old plants of the original host species and cultivars (for common box, cv. Faulkner was used). Cultures were grown for 4 to 6 weeks at 20°C on autoclaved millet grains moistened with V8 broth. Infested and uninfested grains were mixed with autoclaved soil in a ratio of 6% (w/v), and the mixes were used as potting media for transplanting five treated and five control plants per isolate, respectively. Plants were kept in a growth chamber (20°C, 70% RH, 12-h photoperiod). Pots were flooded for 24 h on the 1st and 21st day after transplanting. All plants in infested potting mix showed symptoms of wilt associated with basal stem and root necrosis, similar to those observed on the plants from the field, within 2 and 3 months on lavender and both common box or Port-Orford-cedar, respectively. Additionally, a reduction of root weight ranging from 35 to 68% compared to the control was recorded. Growth reduction was significant at P ≤ 0.019 according to Mann Whitney test. Control plants remained healthy. The same Phytophthora hybrid was reisolated solely from inoculated plants. In Europe, hybrid isolates of P. nicotianae × P. cactorum have been reported on several ornamental plants, including lavender, in the Netherlands and Germany (2,3). However, to our knowledge, this is the first report of this hybrid in Hungary and as a pathogen of common box and Port-Orford-cedar in the world. References: (1) P. J. M. Bonants et al. Phytopathology 90:867, 2000. (2) W. A. Man in ‘t Veld et al. Phytopathology 88:922, 1998. (3) H. I. Nirenberg et al. Mycologia 101:220, 2009.

From 2007 to 2009, necrotic bark lesions at the root collar and lower stem associated with root rot were observed on container-grown cork-bark fir (Abies lasiocarpa var. arizonica, Port-Orford-cedar (Chamaecyparis lawsoniana (A. Murray) Parl. 'Barabits Gold'), lavender (Lavandula angustifolia Mill. 'Hidcote'), flowering currant (Ribes sanguineum Pursh 'King Edward VII'), and lilac (Syringa vulgaris L. 'Belle de Nancy') in six ornamental nurseries in western Hungary. Symptoms also included reduced growth, wilting, and desiccation of branches. Mortality of affected plants ranged from a low level in flowering currant to a high frequency in cork-bark fir (1,000 plants; 50%) and lavender (2,500 plants; 50%). Isolations from necrotic tissues onto PARPB medium (1) yielded 13 isolates of a Phytophthora sp. None of the isolates produced sexual structures, sporangia, or chlamydospores but developed slightly stellate or patternless colonies with loose, aerial mycelium on nonselective carrot agar (CA) at 25°C. One isolate from each host species was further characterized and tested for pathogenicity. Growth on CA was fastest at 25°C (7.9 to 8.6 mm per day) and no growth occurred below 5°C or above 34°C. In nonsterile stream water, persistent, mono- and bipapillate, mostly ovoid, rarely distorted sporangia, measuring 40.5 to 49.4 × 29.8 to 37.3 μm were produced. In pairings on CA with A1 and A2 strains of P. cambivora and P. nicotianae, used as testers, none of our isolates produced gametangia. On the basis of these characteristics, the pathogen from ornamentals appeared to be P. citrophthora (Smith & Smith) Leon. (1). Species identity of all 13 isolates was determined in single-round PCR assays with the P. citrophthora-specific primer-pair Pc2B/Pc7 (2) and/or by sequencing the rDNA internal transcribed spacer (ITS) regions amplified with the universal ITS1/ITS4 primers. The primers Pc2B and Pc7 generated a single DNA fragment of the expected size (approximately 210 bp), and the rDNA ITS sequences (NCBI Accession Nos. GU723282, GU723284, GU723285, and GU723287) showed 99 to 100% homology with many GenBank sequences (e.g., HQ697232) of P. citrophthora as the closest match. Pathogenicity to the original host plant cultivars was tested on 2- or 3-year-old healthy plants potted in sterile soil and inoculated at the root collar (2 replicates per isolate). A 4-mm-diameter bark plug was removed and a mycelial disc of the same size from an actively growing CA culture was placed into the hole. Control plants received sterile CA plugs. Inoculation points were sealed with sterile moist cotton and Parafilm, covered with sterile soil, and then the plants were kept in a greenhouse at 24 ± 4°C. Symptoms identical to those observed on the naturally diseased hosts developed on inoculated plants within 3 months. Control plants remained healthy. P. citrophthora could be reisolated only from the infected plants. The pathogen is polyphagous, widely distributed (1), and has been associated with woody ornamentals in nurseries (3). However, to our knowledge, this is the first record of P. citrophthora in Hungary. The pathogen has to be considered as a threat to ornamental production within Hungary. References: (1) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN, 1996. (2) A. Ippolito et al. Eur. J. Plant Pathol. 108:855, 2002. (3) B. W. Schwingle et al. Plant Dis. 91:97, 2007.

Collar and root necroses associated with severe wilting and desiccation of foliage were observed on box (Buxus sempervirens) growing in a public garden in Budapest (2002), and on Nordmann fir (Abies nordmanniana) and Port Orford cedar (Chamaecyparis lawsoniana) produced in a 12 ha ornamental nursery of Western Hungary (2007). The disease was sporadic on Nordmann fir, but was abundant on box and Port Orford cedar, resulting in 25–30% mortality. Isolations from lower stems and roots consistently yielded cultures typical of Phytophthora, developing stellate-radiate colonies with low aerial mycelium on carrot agar (CA) and V8 juice agar, or were featureless on potato dextrose agar at 25°C. Cultures lacked sexual structures, sporangia or chlamydospores. Three isolates (IMI 390920, CBS 124086, CBS 123840), one from each host plant, were further characterized. Optimum and maximum temperatures for growth on CA were 30 and 38°C, respectively. Mean radial growth-rate at 30°C ranged from 9·2 to 9·4 mm day−1. In non-sterile stream water, persistent, ellipsoid-ovoid, non-papillate, rarely internally proliferating sporangia were produced with dimensions of 73 ± 7 × 33 ± 4 μm (average of the three strains). The rDNA ITS sequences (GenBank Accession Nos. FJ801357, GU230789 and GU230790) showed 100% congruence with accessions deposited as ‘P. sp. niederhauserii’ (Abad & Abad, 2003). The morphological characteristics are also consistent with published descriptions given the same name. However, a valid name according to nomenclatural rules has not yet been published for this species of Phytophthora and we refrain from naming it here. Pathogenicity to the original host plant species was verified by wound-inoculating at the root collar of 2-year-old potted plants with mycelial CA discs. Symptoms identical to those observed on naturally infected plants developed within 3–6 weeks, and our Phytophthora alone was re-isolated. Control plants inoculated with sterile CA remained healthy. A species of Phytophthora named as ‘P. sp. niederhauserii’ has been reported on other hosts in Europe (e.g. Herrero et al., 2008; Cacciola et al., 2009; Moralejo et al., 2009). This is the first record of this formally unnamed Phytophthora from Hungary. This work was supported by the Hungarian Scientific Research Fund (OTKA) grants K46228, K61107, IN64168 and IN71349.

Phytophthora ITS Clade 6 contains numerous informally designated taxa and recently described new species. We report here on the characterisation of the two informally designated taxa P. taxon Forestsoil and P. sp. hungarica. The first culture of P. taxon Forestsoil was collected from soil of an oak‐ Carpinus forest in 1998 and partially characterised later [1]. Subsequently, a few isolates from alder soil with identical ITS sequences to P. t. Forestsoil were reported as P. sp. sylvatica and P. sp. H‐6/02 at Genbank in 2007. At the same time other isolates from alder soil, differing from P. t. Forestsoil and its synonyms in their colony pattern on carrot agar (CA) and at the same 4 positions in their ITS, were named P. sp. hungarica, P. sp. H‐7/02 and P. sp. H‐8/02. Additional ‘hungarica’ isolates were then collected in Alaska [2], also from alder soils or nearby waterways. In our detailed study, the only consistent morphological difference between ‘Forestsoil’ and ‘hungarica’ was still the culture pattern on CA. Both taxa showed similar growth rates and cardinal temperatures, produced similar sporangia, were homothallic with mostly paragynous antheridia and aplerotic oospores often with several ooplasts. Concatenated analyses using 4 nuclear and 2 mitochondrial gene sequences were in concordance with the morphological and physiological features supporting the grouping of ‘Forestsoil’ and ‘hungarica’ isolates into 2 very closely related but distinct clades. These results might help to unravel the taxonomic and phylogenetic position of these informally designated taxa.