Viburnum Tinus Research Articles

First report of Phytophthora hedraiandra on Viburnum tinus in Italy

) is an ornamental shrub widely used inprivate gardens and public parks for background, screen planting, or clippedand unclipped hedging. It is commonly present in natural wood stands inthe Mediterranean area. In spring 2004, several cases of decline and mor-tality of laurustinus plants were observed in nurseries located in central Italy,particularly in Pistoia province (Tuscany, Italy). Symptoms were character-ized by collar and root rot. Affected plants showed wilting of leaves and shoots.A Phytophthora spp. was isolated from infected tissues and soilremoved from the root zone of plants showing symptoms. Isolations weremade by direct plating of tissue fragments cut from the margin of collarnecrosis, and from soil by baiting with rhododendron leaves. The selectivemedium PARBhy (Vettraino et al., 2001) was used. The species isolatedwas identified as Phytophthora hedraindra, based on cultural andmorphological features (De Cock & Levesque, 2004). Six single hyphaltip isolates, obtained from different diseased and dead plants, wereanalysed for morphological features. They produced smooth distinctpapillate, ovoid to obpyriform caducous sporangia (length/width average1·3), with a short stalk (av. 2 µ m), terminal chlamydospores, and werehomothallic with smooth, globose oogonia (av. 30 µ m in diameter),mostly paragynous sessile or short-stalked antheridia (av. 11·5 µ m long),occasionally amphigynous, oospores commonly aplerotic (av. 32 µ m indiameter). Identification was confirmed by sequencing the ITS region ofrDNA of all the six isolates and comparing the sequences (overall lengthof 792 bp) with those of Phytophthora pathogenicity of species present in the NCBI database.The sequences of four isolates displayed 100% homology with sequenceAY707987 (P. hedraiandra isolated from Viburnum spp. in the Nether-lands), whilst the sequences of the other two isolates had 99% homology.The sequences of four isolates were submitted to GenBank: accessionnumbers AM049389 and AM049390 were given to the ITS sequences ofisolates ISPaVe 1866 and ISPaVe 1867, respectively (which displayed100% homology with AY707987), and AM049391 and AM049388 tothe ITS sequences of isolates ISPaVe 1868 and ISPaVe 1865 (which differedby one and two bases, respectively, from AY707987). All the P. hedraiandraITS sequences displayed common single base pair substitutions atpositions 74, 100, 101 and 686 in comparison to P. cactorum ITS sequences.Pathogenicity tests were conducted by soil infection on 3-month-oldpotted laurustinus plants using the isolates ISPaVe 1865, 1866, 1867 and1868. Sporulation was induced by 24 h flooding of the soil. One monthafter inoculation, symptoms were produced similar to those observed onnaturally infected plants. Controls remained healthy; P. hedraiandra wasreisolated from infected collar and roots. This is the first report ofP. hedraiandra as agent of collar and root rot of V. tinus in Italy.ReferencesDe Cock AWAM, Levesque CA, 2004. New species of

First record of Pseudomonas syringae pv. viburni in the UK

Various Pseudomonas syringae pathovars cause leaf spots and cankers of hardy nursery stock species in the UK, including P.s. pv. syringae on lilac, P.s. pv. berberidis on Berberis spp. and P.s. pv. philadelphi on Philadelphus spp. (Roberts, 1997). Leaf spots on some other hosts are attributed to P.s. pv. syringae or to P. syringae pv. undetermined. Occasionally Central Science Laboratory has received samples of Viburnum spp. with watersoaked leaf spots from which P. syringae has been isolated; one was from Viburnum tinus in 1986. The isolate, a typical LOPAT group 1 member of P. syringae (Lelliott & Stead, 1987), was placed in the National Collection of Plant Pathogenic Bacteria (NCPPB) as NCPPB 3450 and was listed under P.s. pv. viburni with a ‘b’ ranking, denoting authenticity not verified. More recently, plants of Viburnum sargentii with typical bacterial leaf spots were received from a Lincolnshire nursery and from which LOPAT 1 strains were isolated. Host tests confirmed pathogenicity on Viburnum sargentii but it was weaker on Viburnum opulus var. Sterile. Two isolates from V. sargentii on the same nursery, taken at different times (CSL 4205 and 4206), were acceded to the NCPPB as NCPPB 4265 and NCPPB 4266, respectively. Fatty acid profiles obtained were typical of P. syringae. REP-PCR based on primers from the repetitive enterobacterial consensus sequence and BOX-PCR, based on primers from the BOX A subunit, were carried out (Stead et al., 2000). Fingerprints were compared with those of reference strains of all validly named P. syringae pathovars held in the NCPPB, including P.s. pv. viburni (NCPPB 1921, the only authentic strain). upgma dendrograms of both assays showed that NCPPB 3450 did not have the profile of P.s. pv. viburni but was very similar to that of P.s. pv. maculicola and P.s. pv. tomato. However, NCPPB 4265 and NCPPB 4266 had profiles very similar to that of the P.s. pv. viburni type strain and were different from all other reference strains. Bradbury (1986) lists the known distribution as USA and Spain, with the Spanish strains coming from a rot of tobacco. This is the first authentic record of P.s. pv. viburni in the UK. The precise taxonomic position of NCPPB 3450 remains uncertain. This work was funded by DEFRA Plant Health Division Project PH0154.

Treefall Gaps and Regeneration Composition in the Laurel Forest of Anaga (Tenerife): a Matter of Size?

The size of treefall gaps is an impor- tant determinant of regeneration composition in tropical and temperate forests. Preliminary stud- ies in the laurel forest of Tenerife have shown that small gaps ( 100 m 2 ) are present in the laurel forest, we analyzed the regeneration in these large uncommon gaps, considering their potentially important role in the dynamics of the system. Our main hypothesis is that large gaps are important disturbance to en- sure the regeneration and stablishment of shade intolerant species.Only five gaps larger than 100 m 2 (ranging from 125-268 m 2 ) were found in the study area. Data from a further 20 small gaps ( < 100 m 2 ), analysed in a previous study, was also included. Control plots were examined close to the gaps in order to determine regeneration below the closed canopy. We did not find a sig- nificant difference between regeneration density in the gaps ( < 100 m 2 ) and regeneration below the canopy in the control plots. Contrary to our expectations, regeneration was lower in the large gaps than under the canopy. The open canopy in the large gaps increases light intensity, and has a negative effect on the germination and growth of shade-tolerant tree species like Viburnum tinus (although non-statistically significant); however, the increase in light intensity is not sufficient to stimulate the germination of shade-intolerant tree species. The effects of treefall gaps in the dynamics of the laurel forest of Anaga should be not considered as significant in comparison to other factors such as human disturbances or infrequent disturbances (land slides or hurri- canes).

Study of some characteristic Mediterranean vegetation species best suited for renaturalization of terminal-phase municipal solid waste (MSW) landfills in Puglia (Southern Italy)

Natural recovery of worked-out or closed municipal solid waste (MSW) landfills is a current topic, but knowledge about the adaptability of Mediterranean vegetation species to such stressful conditions is still quite poor. Autochthonous plants were selected to withstand the stresses such as hot climate and drought typical of Mediterranean areas; this characteristic potentially allows the plants an easier, efficient adaptation. Our aim was to provide information in order to obtain an adequate quality of environmental renewal of a landfill and a reduced management cost while ensuring rehabilitation to an acceptable naturalistic state. The investigation lasted 3 years; some Mediterranean scrub native plant species were selected and monitored in their morphological (total and relative height, basal diameter, number of inter-nodes) and physiological (photosynthetic rate and water potential) activity. In order to test dependence on CO 2 concentration, different meteorological parameters were also monitored. Ceratonia siliqua , Phillyrea latifolia , Olea europaea and Quercus ilex showed considerable adaptability, reacting positively to every improvement in environmental conditions, particularly those of a meteorological nature. Survival and growth was satisfactory in Hedysarum coronarium , Medicago sativa , Lotus corniculatus , Rosmarinus officinalis , Myrtus communis and Viburnum tinus . Fraxinus ornus and Acer campestre suffered stress during the summer dry period and recovered quickly when atmospheric conditions improved. A drop irrigation system to ensure a satisfactory soil moisture during summer dry periods was the fundamental element for survival.

Nitrogen Fertilization Using Hydroponic Cultures to Fertigate Ornamental Shrubs

ABSTRACT The total nitrogen (N) concentration and nitrate/ammonium ratio (NO3 −/NH4 +) in nutrient solutions were optimized in sand cultures and in 15N experiments for laurustinus (Viburnum tinus), tobir (Pittosporum tobira), and strawberry tree (Arbutus unedoL.) under controlled conditions during three growing cycles. Results from the 15N experiment suggest that Arbutus unedo and, to a minor extent, Pittosporum could regulate the N-NH4 + absorption independently of the external concentration and reduce the toxic effects of N-NH4 +. For Viburnum tinus plants, however, higher external N-NH4 + concentration increased root N-NH4 + and, therefore, could have toxic effects. The optimal N concentration in nutrient solutions and in nitrate-only nutrition would be close to 4.6 mmolc L−1 for Viburnum tinus and close to 5.8 mmolc L−1 for Pittosporum tobira, with a 70/30 (%) NO3 −/NH4 + ratio. For Arbutus unedoL., a total N concentration higher than 9 mmolc L −1 is suggested, with a 70/30 NO 3 −/NH 4 + ratio. Plant-tissue reference levels were obtained for their use for nutritional diagnosis of ornamental shrubs.

Phytochemical constituents and hepatoprotective activity of Viburnum tinus

From the leaves of Viburnum tinus L. (Adoxaceae) two acylated iridoid glucosides (viburtinoside A and B), a coumarin diglucoside scopoletin 7- O-β- d-sophoroside and a natural occurred dinicotinic acid ester 2,6-di- C-methyl-nicotinic acid 3,5-diethyl ester were isolated. In addition to these, 10 known compounds were isolated, namely two bidesmosidic saponins, a hexamethoxy-flavone and five flavonol glycosides, as well as suspensolide A and oleanolic acid were isolated for the first time in this genus and species, respectively. The structures were determined mainly by spectroscopic methods (UV, IR, ESI-MS, 1H-, 13C NMR and DEPT). Toxicity of the investigated extract was determined (LD 50 = 500 mg/kg). CCl 4-induced hepatotoxicity has been evaluated in terms of the determination of alanine aminotransferase (ALT), aspartate aminotransferase (AST), lipid peroxide and nitric oxide levels in serum and compared using adult male rats weighing 150–180 g. Their highly elevated levels were significantly reduced by treatment with the investigated aqueous methanol extract in dose-dependant manner.

Feed blocks as a supplement for goat kids grazing natural Tunisian rangeland during the dry season

Two experiments were conducted to investigate the effects of PEG and feed blocks on digestion of shrub species consumed by goats (experiment 1) and kid growth while browsing during the dry season (experiment 2). In experiment 1, in vitro gas production was determined using a rumen fermenter. Six shrub species were incubated separately ( Erica arborea, Phillyrea angustifolia, Pistacia lentiscus, Myrtus communis, Quercus suber, and Viburnum tinus). Effects of polyethylene glycol (PEG 4000) and feed block supply were investigated. In experiment 2, 21 local kids, 18.75 (±1.4) kg body weight (BW) were allowed to browse in shrub-lands and allocated to three treatments in a production trial lasting 147 days (July–December). Control group receive no supplement, whereas the two other groups received either PEG-free (B) or PEG-containing feed blocks (B-PEG). All shrubs were low in crude protein (59–91 g kg −1 dry matter) but high in total condensed tannins; mean content was 43 g kg −1 DM (8.8–65) for bound condensed tannin and 205 g kg −1 DM (10.8–363) for free condensed tannin. Gas volume produced after 24 h differed among shrub species (P<0.05). V. tinus produced the highest volume (77.8 ml g −1 organic matter) and Q. suber the lowest (35 ml g −1 OM). The mean rate of fermentation was 0.135 h −1 (0.121–0.150 h −1). PEG addition increased gas production by 48.5%, volatile fatty acid by 38.4% and organic matter fermented by 41.7% of the mixture of shrubs (P<0.05). In the practical trial, the use of blocks with and without PEG avoided BW loss of the goats under dry season. While the control group lost 19 g day −1, the bloc supplemented groups grew at 12 g day −1 (−PEG) and 24 (+PEG) g day −1.

Effects of rejuvenation on cutting propagation of Mediterranean shrub species

Abstract: Two tests (April and August) on cutting propagation of seven Mediterranean shrub species (Arbutus unedo, Laurus nobilis, Myrtus communis, Olea europaea var. sylvestris, Phillyrea latifolia, Pistacia lentiscus and Viburnum tinus) were carried out to compare rooting percentage of cuttings from shoots of mature plants with those from rejuvenated plants (1.5-year rooted cuttings). Best rooting percentages were obtained by rejuvenated material. Rejuvenated Laurus nobilis, Myrtus communis, Olea europaea, Phillyrea latifolia and Viburnum tinus exhibited rooting percentages higher than 50%, whereas for Arbutus unedo, and Pistacia lentiscus the percentages were lower.

Sheep and goat preference for and nutritional value of Mediterranean maquis shrubs

The objective of this study was to evaluate the nutritive value, intake and preferences of sheep and goats for the dominant six shrubs of the holly oak maquis-type shrublands in Croatia. The experimental sheep ( n = 12, mean weight 28.5 kg) were a local Croatian mixed breed. The experimental goats ( n = 12, mean weight 13.4 kg) were a mixture of domestic goats crossed with Saanen and Alpine breeds. Sheep and goats differed ( P < 0.01) in consumption of almost all of the shrubs. Goats had higher intakes (g/kg B.W., P < 0.01) than sheep of each shrub except Quercus ilex. In Trial 1, shrub intake for goats ranged from 17.7 ± 0.72 g/kg B.W. for Pistacia lentiscus to 33.1 ± 1.40 g/kg B.W. for Erica multiflora. Goats ate more Arbutus unedo ( P = 0.004; 19.9 g/kg versus 14.2 g/kg B.W., respectively); E. multiflora (33.1 g/kg versus 21.9 g/kg B.W., respectively) and Pistacia lenticus (17.2 g/kg versus 10.6 g/kg B.W., respectively) than did sheep. Goats ate twice as much Juniperus phoeniceae ( P = 0.002) as did sheep (21.0 g/kg versus 10.9 g/kg B.W.), and also ate more Viburnum tinus ( P = 0.02) than did sheep (22.6 g/kg versus 13.9 g/kg B.W.). There was a day × treatment interaction ( P = 0.001), with goats eating more A. unedo, E. multiflora, J. phoeniceae, P. lenticus and V. tinus than sheep. In Trial 2, the rank order of preference (highest to least) for goats were Q. ilex, E. multiflora, V. tinus, A. unedo, J. phoeniceae and P. lentiscus. The rank order by sheep was similar: Q. ilex, E. multiflora, V. tinus, J. phoeniceae, P. lentiscus and A. unedo. Overall, goats ate 50.5 g/kg B.W. of shrubs per day, while sheep averaged 26.7 g/kg B.W. each day. Goats are better suited to graze Mediterranean maquis in terms of potential shrub use.

EXPLORING ISRAELI FLORA FOR NEW FLORICULTURE CROPS

Israel and its neighbouring countries in Eastern Mediterranean have been the source of many commercial ornamental plants, especially geophytes. Examples are anemones, ranunculus, cyclamen, hyacinth, Narcissus tazetta. Lilium candidum and several tulips. Our plant introduction project includes also several native plants, which have not been introduced into commercial cultivation yet. The introduction projects include many research stages, starting with the collection of the plants in their native habitat and finalizing when the product is introduced commercially. Many of those plants have a natural short flowering period. It is therefore very important to study the flowering physiology of the plants and develop methods for their flowering control. Some beautiful flowers such as Oncocyclus irises have very short longevity, so it is important to concentrate on their senescence physiology and develop methods to extend their life span. With woody plants the main problem is developing a suitable propagation method. Among the native plants now in the process of domestication are plants of the following groups: Geophytes: Oncocyclus irises, Uriginea maritima, Scilla hyacinthoides, Asphodelus ramosus and several Alium species. Herbaceous annuals and perennials: Lupinus pilosus; Eremostachys laciniata, Helichyrsum sanguineum and Aerva javanica. Woody plants: Viburnum tinus. Several native woody plants are being developed as ornamental pot plants e.g. olive, fig, pistacias and oaks.

Complex Combination of Seed Dormancy and Seedling Development Determine Emergence of Viburnum tinus (Caprifoliaceae)

The shrub Viburnum tinus is widely distributed in mattoral vegetation of the Mediterranean basin. The purpose of the present study was to classify the seed dormancy type and examine the requirements for embryo growth, root protrusion and shoot emergence. Overwintered fruits were collected in western Spain in April 2001 and prepared in three ways: entire pericarp was removed, exocarp and mesocarp were removed or fruits were left intact. Fruits treated in these three ways were subjected to artificial annual temperature cycles or to constant temperature regimes for 1.5 years. Removal of exocarp and mesocarp was necessary for embryo growth and germination. High temperature favoured dormancy alleviation and embryo growth, intermediate to low temperatures favoured root protrusion, and intermediate temperature shoot emergence. There was substantial germination at constant temperature regimes, indicating an overlap between temperature intervals suitable for the different stages of embryo and seedling development. Functionally, V. tinus has the same root and shoot emergence pattern that is described for other Viburnum species considered to have epicotyl dormancy. However, the requirement for high and low temperatures for radicle protrusion and epicotyl emergence, respectively, was missing in V. tinus; these characters are the foundation for the epicotyl dormancy classification. It is concluded that V. tinus does not have epicotyl dormancy. Instead, there is a combination of a weak morphophysiological dormancy and a slow germination process, where different temperatures during an annual cycle favour different development stages. The present study suggests that the first complete seedlings would emerge in the field 1.5 years after fruit maturation in October, i.e. seed dispersal during winter, embryo growth during the first summer, root protrusion and establishment during the second autumn and winter, and cotyledon emergence during the second spring.

First report of ramorum dieback (Phytophthora ramorum) on container‐grown English yew (Taxus baccata) in England

Phytophthora ramorum is a recently described pathogen (Werres et al., 2001) causing oak mortality in parts of North America and is commonly known as sudden oak death (Rizzo et al., 2002). In North America it also causes ramorum dieback or ramorum leaf blight on a range of woodland plants. In Europe, it is recorded as causing dieback of rhododendron and viburnum (Lane et al., 2003) but also of a number of other ornamental plants, e.g. Pieris (Inman et al., 2003). In May 2003, Defra’s PHSI inspected a batch of 20 young container-grown plants of Taxus baccata (English yew; Taxaceae) from a nursery in north-west England from which P. ramorum had previously been found on Viburnum tinus. The yews were showing an overall bronzing, typical of drought stress, but on half of the plants there was a more discrete shoot dieback, similar to symptoms caused by P. ramorum observed on conifers (e.g. Sequoia) in North America. A whole plant showing dieback was sent to CSL for diagnosis. Stem sections were excised from the leading edge of the shoot dieback, surface-decontaminated by rinsing in tap water then transferred to a semiselective medium (P5ARP[H]) (Lane et al., 2003). A Phytophthora species was consistently isolated, with morphological characters typical of P. ramorum (Werres et al., 2001). The culture gave a positive reaction with both conventional and real-time PCR assays, designed to specifically detect P. ramorum (KJD Hughes, unpublished data). In addition, ITS sequence from the yew isolate (GenBank AY 520152) was shown to be identical to P. ramorum sequences already published in the GenBank database. The Taxus isolate was inoculated onto healthy, wounded needles of young shoots of T. baccata and infection spread from the needles to the stem, causing a dieback of the detached stem. The pathogen was re-isolated to complete Koch’s postulates. No symptoms were observed with the negative control (using an uninoculated agar plug). Following the confirmatory diagnosis, statutory plant health action was taken to eradicate the disease and there were no further findings of the pathogen on the site. This is the first report of Phytophthora ramorum causing shoot dieback of Taxus baccata in England and the first occurrence of the pathogen worldwide on a member of the Taxaceae (yew family).

First Report of Powdery Mildew Caused by Erysiphe viburni on Viburnum tinus in California.

In June 2003, landscape and potted nursery plants of laurustinus (Viburnum tinus) in Monterey County, California, were found to be infected with a powdery mildew. White, ectophytic mycelial and conidial growth were present primarily on adaxial leaf sides with only sparse growth on abaxial surfaces. Severely infected leaves were buckled and slightly twisted. Affected leaf tissue exhibited slight purple-to-brown discoloration. Appressoria were opposite and lobed. Conidia were produced singly, cylindrical in shape, and measured 31 to 42 × 14 to 19 μm. No fibrosin bodies were observed in the conidia, and the conidia germinated at the ends. Ascomata were not observed. The fungus was identified as Erysiphe (section Microsphaera) viburni Duby (= Microsphaera sparsa Howe = Microsphaera penicillata [M. sparsa is not completely synonymous with M. penicillata because M. sparsa is defined as only those mildews that attack viburnum, whereas M. penicillata was defined as attacking dogwood, alder, etc.]) (1,2). Pathogenicity was demonstrated by gently pressing infected leaves with abundant sporulation onto recently expanded leaves of four, large, potted laurustinus in standard 5-gallon nursery containers (19 liters). Twelve leaves per plant were inoculated. The plants were incubated in a greenhouse (23 to 25°C). After 9 to 10 days, powdery mildew colonies developed on approximately 50% of the inoculated leaves. Such colonies were morphologically similar to the original fungus. Uninoculated control plants did not develop powdery mildew. Using the same technique, inoculating fully mature leaves of the same plants did not result in disease. To our knowledge, this is the first report of Erysiphe viburni infecting V. tinus in California. At some landscaped areas the powdery mildew was extremely severe, causing plants to take on a whitish appearance and resulting in all new foliage being misshapen. E. viburni has also been reported to infect V. japonicum in California.

First Report of Southern Blight Caused by Sclerotium rolfsii on Laurustinus.

Laurustinus (Viburnum tinus L.), native to the Mediterranean Region, is an evergreen shrub commonly used as a specimen shrub or small tree or used in border plantings. During August 2003, a blight occurred on 2-year-old-plants of laurustinus growing in pots in a nursery in eastern Sicily (Italy). Disease incidence ranged from 2 to 5% across the field. Symptoms included 3 to 4 cm long lesions and the development of white mycelial strands and brown, 1.0 to 1.8 mm, nearly spherical sclerotia on the crown of plants at the soil line that are typical of Sclerotium rolfsii Sacc. The foliage of infected plants wilted, followed by a sudden collapse of the plant. The fungus was consistently isolated on acidified potato dextrose agar (PDA) (pH 4.5) by plating symptomatic tissues that were surface disinfested (1.2% NaOCl) for 1 min. and rinsed in sterile water. Pathogenicity tests were performed by sprinkling 50 sclerotia, obtained from infected oat kernels (2), on the soil surface around the collar of each of 10 healthy, potted 1-year-old plants of laurustinus. Five of the plants were previously wounded on the crown 1.5 cm above or below the soil line with a sterile needle. Five noninoculated plants served as controls. All plants were maintained at 25 ± 2°C and enclosed for 72 hr in polyethylene bags (90 to 95% relative humidity). Blight symptoms similar to those seen in nursery were observed on inoculated plants 20 to 25 days after inoculation, while no symptoms developed on control plants. Koch's postulates were fulfilled by reisolation of the fungus on acidified PDA from all infected laurustinus plants. S. rolfsii was previously recorded on Prague viburnum (Viburnum × pragense L.) as the causal agent of southern blight (1). To our knowledge, this is the first report of southern blight caused by S. rolfsii on laurustinus.

Plate 491. Viburnum tinus ‘Eve Price’Viburnaceae

Summary.The taxonomy, distribution and cultural requirements of the European Viburnum tinus L., and particularly of the cv. ‘Eve Price’ are discussed; an illustration is provided, together with a full description.

EFFECT OF SALTS ON ORNAMENTAL GROUND COVERS FOR GREEN URBAN AREAS

EFFECT OF SALTS ON ORNAMENTAL GROUND COVERS FOR GREEN URBAN AREAS

First Report of Phytophthora ramorum on Camellia japonica in Spain.

Phytophthora ramorum causes shoot and foliar blight on Rhododendron spp., Viburnum spp. (4), Pieris spp. (2), Kalmia latifolia, and Camellia spp. in several European countries (1-4). In December 2002, we received diseased C. japonica growing in containers from several nurseries in Galicia (northwestern Spain). These young camellia plants had leaves with brown-to-black, water-soaked lesions with diffuse borders that expanded into larger blotches resulting in dead leaves and necrotic lesions on the petioles. Eventually the entire plant wilted and died. Tissue from the leading edge of the lesions was transferred to a selective medium (V8 agar supplemented with pimaricin (10 μg/ml), rifampicin (25 μg/ml), hymexazol (5 μg/ml), and benomyl (5 μg/ml)) and incubated for 3 to 4 days at 20°C in the dark. A Phytophthora sp. was isolated, transferred to carrot piece agar (CPA) (4), and incubated in alternating light. Isolates exhibited coralloid mycelium with concentric rings and a radial growth of 2.5 to 3 mm per day at 20°C. The hyaline-to-yellowish chlamydospores were terminal and intercalary, occasionally lateral, and 24 to 74 μm in diameter. The caducous, sympodial, semipapillate sporangia had a length/breadth ratio of 1.8 to 2.1 and a short pedicel (<5 μm) or no pedicel. Oogonia, antheridia, and oospores were produced by pairing the isolates with P. cryptogea A2 tester BBA 63651 (3,4) provided by S. Werres. Oogonia were subspherical and smooth-walled, antheridia were amphyginous, and oospores were plerotic. The internal transcribed spacer-rDNA polymerase chain reaction (PCR) product obtained by using DNA extracted from mycelium and nested PCR with P. ramorum-specific primers was the size reported for P. ramorum (1). Pathogenicity of the isolates was confirmed by inoculating detached leaves of C. japonica. Five isolates were tested on leaves from 15 young plants growing in containers. Three leaves of each plant were detached and inoculated with each isolate. Leaves were dipped for 5 min into a suspension of sporangia and mycelial fragments and maintained at 20°C and 95% humidity. After 15 days, lesions that developed from the petiole base exceeded 25 mm, and the pathogen was consistently reisolated from the lesions. Leaves inoculated with water from sterile CPA plates did not develop symptoms. A C. japonica isolate has been deposited in the Spanish Type Culture Collection (CECT 20519). To our knowledge, this is the first report of P. ramorum on C. japonica in Spain, though the pathogen has been isolated from Rhododendron spp. and Viburnum tinus growing in several nurseries in Galicia.

Estimation of relative water use among ornamental landscape species

Low water use plantings may enhance water conservation in dry landscapes. However, appropriate plant selection is hindered by the dearth of information available on the water needs of different species. A direct method of classification was tested under the hypothesis that relative water use by woody landscape species growing in 3.8 l containers would be representative of the water use of the same species in the landscape. Four species of distinctly different ecological origin ( Leucophyllum frutescens, Spiraea vanhouteii, Viburnum tinus, Arctostaphylos densiflora) were chosen in order to obtain a wide range of responses, and their water use was measured in plants growing in 3.8 l containers and compared to that of the same species growing in drainage lysimeters, representative of landscape conditions. Half of the plants were subjected to successive cycles of stress by withholding water after irrigation to container capacity in containers, or applying a fraction of the potential evapotranspiration in lysimeters. The good fit of the regression of average daily water use by lysimeter plants on average daily water use by container plants ( R 2=0.87, P<0.01) reflects the consistency of relative water use of the four species. Measurement of water use at the end of nursery production may be useful for predicting the relative water use of various species after establishment in the landscape.

The functional morphology of juvenile plants tolerant of strong summer drought in shaded forest understories in southern Spain

It has been hypothesized that plants cannot tolerate combined shade and drought, as a result of morphological trade-offs. However, numerous plant species are reportedly widespread in shaded forest understories that face drought, whether seasonal or occasional. We studied juveniles of six plant species that cope with strong summer drought in the understoreys of mixed Quercus forests in southern Spain: the tall-shrubs Phillyrea latifolia and Viburnum tinus, the perennial herb Rubia peregrina, the small shrub Ruscus aculeatus, and climbers Hedera helix and Smilax aspera. All of these species persist in evergreen shade (c. 3% daylight). Two other species were studied as comparators, Ruscus hypoglossum, less tolerant of drought, and Ceratonia siliqua, less tolerant of shade. Morphological and chemical variables relevant to shade and drought tolerance were measured for juveniles in a range of sizes, and also for the leaves of mature plants. The species converge in features that confer tolerance of shade plus drought by reducing demand for resources. Demand for water is reduced through a moderate to high below-ground mass fraction and low to moderate specific leaf area (respectively 0.22–0.52 and 112–172 cm2 g−1 at 1.00 g total dry mass). Demand for both irradiance and water is reduced through a low to moderate foliar nitrogen concentration and long-lived, physically protected leaves (≥2 yr). The species also converge in features that confer tolerance of either low irradiance or drought through specialized capture of resource, without precluding the other tolerance. These features include deep roots relative to shoot size, moderately higher specific leaf area in shade (1.2–2.0 × that in sun) and higher chlorophyll:nitrogen ratio in shade. Foliar chlorophyll per unit mass was higher in shade, but chlorophyll was not necessarily synthesized in greater amounts; rather, it was higher apparently due to shade effects on structural features linked with specific leaf area. In contrast, N per unit mass was higher in sun leaves independently of specific leaf area. Despite these convergences, the species diverge considerably in their root mass allocation and architecture, leaf saturated water content, density of stomata and guard cell size. No single narrowly defined functional type is needed for tolerance of shade plus drought.

Relations between efficiency of water transport and duration of leaf growth in some deciduous and evergreen trees

Shoot and leaf growth rate as well as shoot hydraulic conductance per unit leaf area (KSL) were measured on three evergreen (Viburnum tinus L., Prunus laurocerasus L., Laurus nobilis L.) and three deciduous (Corylus avellana L., Juglans regia L., Castanea sativa L.) trees growing under the same environmental conditions. The times required to complete shoot growth (27 days for P. laurocerasus to 51 days for V. tinus) and leaf expansion (24 days for C. sativa to 42 days for C. avellana) were very different among the studied species. These species also differed in KSL that ranged between 1.5 and 3.5 e-4 kg s–1 m–2 MPa–1 in C. avellana and C. sativa, respectively, with intermediate values recorded in the other species. A strong, negative and statistically significant correlation was found to exist between KSL and the time required for complete leaf expansion. This suggests that duration of leaf growth is shortened by the high hydraulic efficiency of the shoot. In contrast, no statistically significant relationship was found to exist between KSL and shoot growth rate. Whether a high leaf growth rate can be interpreted as advantageous to plants or it is only an epiphenomenon of the high efficiency in the vertical water transport is discussed.