bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of Nitrogen Fertilizers on Growth, Spore Production and Germination, and Biocontrol Potential of Trichoderma and Gliocladium
Authors: Watanabe Naomichi , Lewis Jack A. , Papavizas George C.
Published: May 2008

The mycelial weight of eight out of nine isolates of Trichoderma spp. and Gliocladium virens increased in media supplemented with 2000 mg/l of nitrogen (N) from the fertilizers NH4Cl, NaNO3, and a commercial 20–20–20. In general, the greatest increase in growth (up to 311 %) occurred with 20–20–20. The extent of growth was similar with either NH4Cl or NaNO3, but was less than that with 20–20–20. Measured by radial development on agar surfacesgrowth of isolates was either not affected or was constricted by supplemental fertilizers. Production of conidia by six out of eight isolates was stimulated by 20–20–20 but not by NH4Cl or NaNO3. Germination of conidia of all isolates, generally was high (> 85 %) on amended and nonamended agar. Chlamydospore formation by three Trichoderma isolates in liquid media was not affected by fertilizers. Antagonism or overgrowth of the pathogen Rhizoctonia solani by Trichoderma isolates in culture was reduced appreciably by NaNO3, but was not affected by NH4Cl or 20–20–20. Addition of 20–20–20 to natural soil did not reduce further the survival of R. solani caused by germling preparations of six out of seven Trichoderma isolates. However, reduction in survival of the pathogen caused by a T. hamatum isolate was stimulated further (45 %) by the fertilizer.
Detection of the Grapevine Fanleaf Viruses Away from the Period of Vegetation
Authors: Walter B. , Etienne L.
Published: May 2008

Best conditions for the detection of AMV (Arabis Mosaic Virus) and GFV (Grapevine Fanleaf Virus) in grapevine tissues at different seasons in the year have been determined.

Leaves, rootlets and wood shavings are good virus sources for ELISA. The commonly used nicotine solution can be replaced by a PBS‐ or Tris‐HCl buffer, as extraction medium, provided its molarity is high and it contains polyvinylpyrrolidone.

In our conditions, detection of AMV and GFV was possible in leaves from May to October, There was no clear‐cut advantage in using extracts prepared either from leaves obtained from the top, middle or bottom parts of a plant.

Away from the period of vegetation, the use of wood shavings allowed virus detection, even when cuttings were harvested a few months ago and kept at 6°C.
Remarks on the Biological Activity of Aspergillomarasmine A Fe3+ Chelate and Other Iron Transporting Phytotoxins with Reference to their Role in the Photodegradation of Aromatic Amino‐Acids in Infected Plant Leaves
Authors: Barbier M.
Published: May 2008

Aspergillomarasmine A Fe3+ chelate catalyzes the photodecomposition of a phenylalanine containing peptide and of L‐phenylalaline itself to benzaldehydein vitro.This reaction can be repeated with FeCl3so that the phytotoxin appearsto be essentially an iron carrier from the microorganisms to the leaf surface where occur the leaf destructions.
A Screening Method for Detecting Resistance Against Cassava Bacterial Blight Disease
Authors: Pacumbaba R. P.
Published: May 2008

Inoculation of the cassava bacterial blight (CBB) pathogen by using a modified pair of tongs on cassava shoots (1‐month‐old) in the glasshouse and in the field resulted in symptoms within 24‐48 h on susceptible cassava lines ‘02864’ and ‘M'pelolongi’. Gum exudates on inoculated young stems and die‐back appeared 7‐12 and 20‐25 days later, respectively. No symptoms of CBB were observed on cv. ‘Kadanga Malombe’. Symptom development and CBB ratings on 3‐month‐old cassava shoots in the glasshouse and inthe field were not consistent. Inoculation of CBB pathogen on 521 cassava shoots (1‐month‐old) using the tongs method gave 81 and 82 resistant and moderately resistant plants to CBB, respectively. The tongs method is an excellent field‐screening technique for detecting resistance to CBB on 1‐month‐old cassava shoots.
Inhibition of Plant Viruses by Human Gamma Interferon
Authors: Vicente M. , De Fazio G. , Menezes M. E. , Golgher R. R.
Published: May 2008

In order to evaluate the inhibitory effect induced by gamma interferon (Hu g IFN) on plant viruses, pre‐inoculation treatments (brushing the leaves) were carried out in two different plant‐virus systems: D. stramonium* TMV and G. globosa* PVX. Results showed that Hu g IFN induced a higher inhibitory effect (IP = 90%) in D. stramonium* TMV system (Table 1). Comparing the antiviral effect of the three IFNs: gamma, alpha and beta‐like interferons, it was verified that Hu g IFN was more effective than the other two (Table 2).

Hu g IFN was also used for post‐inoculation treatments (incubation of tobacco leaf‐discs) and using different dilutions a dose response curve could be obtained (Fig. 1). Hu g IFN inhibitory effect was confirmed by the neutralization of its inhibitory effect using monoclonal antibody (Table 3).

Results suggest that although the three IFNs differ in their composition, they present similarities in their biological activities probably triggering an antiviral state in plants.
Eggplant Mottled Dwarf Virus Associated with Vein Yellowing of Honeysuckle
Authors: Martelli G. P. , Cherif C.
Published: May 2008

A rhabdovirus isolated in Tunisia by mechanical inoculation from honeysuckle (Lonicera sp.) plants with vein yellowing, was compared with a Tunisian isolate of eggplant mottled dwarf virus (EMDV). The two viruses had similar host ranges and caused the same symptoms in artificially infected hosts. The honeysuckle virus induced in eggplant a syndrome indistinguishable from that typical of EMDV. The two viruses could not be differentiated serologically, had particles of the same size and elicited identical cytopathological alterations in naturally and artificially infected hosts. Honeysuckle is the first host, besides eggplant, found to be naturally infected with EMDV.
Effect of Light on Uredospore Germination and Germ Tube Growth of Soybean Rust (Phakopsora pachyrhizi Syd.)
Authors: Koch E. , Hoppe H. H.
Published: May 2008

The effect of light on uredospore germination and germ tube growth of Phakopsora pachyrhizi was studied. Frequency of uredospore germination was only partially reduced by high light intensity (> 1,9 * 104 mW * m−2). In uredospores unilaterally irradiated with polychromatic light germ tubes always emerged from the shadowed side. Already developed germ tubes showed a negative phototropic response. Both effects were inducible by low light intensities. Negative phototropism of germ tubes was a blue light effect. Light of 441 nm was more effective than that of 422 nm or 372 nm. Red light (> 600 nm) was ineffective, green light (513 nm) induced medium responses. In half‐side illumination studies longitudinal halves of germ tube tips and spores were irradiated under a microscope. The tips of the germ tubes bent into the illuminating beam. In half‐side illumination studies germ tubes always emerged from the illuminated spore halves. Under unilateral illumination liquid paraffin reversed this light “polarization” of spores and the negative phototropism of germ tubes. These results suggest that during unilateral illumination spores and germ tube tips act as a lens focussing the light on the wall farthest away from the light source., There, in uredospores emergence of germ tubes is stimulated and in germ tubes growth is inhibited. As a consequence, under unilateral illumination germ tubes emerge at the shadowed side of the spores and grow away from the light.
Systemic Induction of Resistance in Potato Plants Against Phytophthora infestans by Local Treatment with Hyphal Wall Components of the Fungus
Authors: Doke N. , Ramirez Adan Vite , Tomiyama K.
Published: May 2008

Potato plants (cv.‘Irish Cobbler’ with no major resistance genes to Phytophthora infestans), the lower or upper leaves of which were previously treated with hyphal wall components (HWC) of the fungus by rubbing with carborundum, acquired an induced resistance in other untreated leaves against cultivar‐pathogenic races of P. infestans when challenged by spraying with a zoospore suspension. Such induced resistance was significantly shown to exist from at least 1 to 20 days after induction treatment with HWC. Thus, the treated plants were protected from severe late blight disease while non‐induced control plants finally died of the disease. The induced resistance was due to a reduction of the number of successfully germinating zoospores, and subsequent penetration and then occurrence of hypersensitive‐like cell response to the penetrating organisms.

These results suggested that local leaf tissues of potato plants reacting to HWC may provide some systemic information that activates or enhances some resistance to P. infestans.
Antiphytovirale Wirkungen von 1,5‐Diacetyl‐2,4‐dioxohexahydro‐1,3,5‐triazin (DA‐DHT)*
Authors: Schuster G.
Published: May 2008

Antiphytoviral activities of 1,5‐diacetyl‐2,4‐dioxohexahydro‐1,3,5‐triazine

Substitution of 2,4‐dioxohexahydro‐1,3,5‐triazine (DHT) by two acetyl groups resulted in an antiphytoviral compound, 1,5‐diacetyl‐2,4‐dioxohexahydro‐1,3,5‐triazine (DA‐DHT), which inhibits PVX, PVY, ToMV, TMV and TRV better than DHT, but only after, application at relatively high concentrations (10−2 mol/1). The antiphytoviral activity of DA‐DHT is enhanced by combined treatments with DHT as well as with cyanoguanidine, sodiumalkanemonosulfonate and 2‐anilino‐5‐adamantyl‐1,3,4‐thiadiazole., DA‐DHT reduced the number of symptoms of PLRV bearing potato eye cutting plants to a higher percentage than DHT. But the highest reduction was brought about by combined treatments with DA‐DHT, cyanoguanidine, sodiumalkanemonosulfonate and 2‐anilino‐5‐adamantyl‐1,3,5‐thiadiazole. Moreover, treatments with DA‐DHT increased more than treatments with DHT the mass of potato tubers produced by potato eye cutting plants. Combined treatments with DA‐DHT and the above mentioned substances reduced the natural infection with PLRV of a completely healthy potato stock for about 70 % and that of PVY for about 40 %. Thus, the DA‐DHT containing preparations may be capable of keeping potatoes in a good state of health even in regions with a high infection pressure.
Frequencies of Virulence and Fungicide Resistance in the European Barley Mildew Population in 1985*
Authors: Limpert E.
Published: May 2008

Representative random samples of spores of Erysiphe graminis f. sp. hordei, causing powdery mildew of barley, were taken from the atmosphere by means of a Schwarzbach jet spore sampler over important barley growing areas in Europe and tested in the laboratory for their virulence on host plants with resistance Ml 41/145, Mlg, Mla6, Mla12, Mla7+Mlk, MlLa, Mla1, Mla9, Mla3, Mla13+Ml (Ru3) and mlo. Virulence frequencies mostly showed regional differentiation and efficiency of, the resistance factors generally increased in the order given. Frequency and level of resistance against triadimenol also showed significant regional differences. Against fenpropimorph similar levels of sensitivity were observed in different parts ofEurope, close to that of standard‐isolates, which had a mean position. The results are discussed with respect to current and previous conditions of cultivation, to the spread of the pathogen by wind and towards strategies for more effective use of hostresistance and of fungicides.
Assimilatverteilung in Sommergerstensorten mit unterschiedlicher Resistenz gegenüber dem Echten Mehltau (Erysiphe graminisf. sp.hordei)
Authors: Kern M. , Ibenthal W.‐D. , Heitefuss R.
Published: May 2008

Distribution of assimilates in cultivars of spring barley with different resistance against powdery mildew (Erysiphe graminisf. sp.hordei)

Transport and distribution of radioactive labelled assimilates in spring barley cultivars with different degrees of resistance to powdery mildew were studied after14CO2‐treatment of single leaves. Plants of the cultivars ‘Amsel’ (susceptible), ‘Asse’ (adult plant resistant), and ‘Rupee’ (resistant) were analyzed at the vegetative growth stage (5. leaf unfolded) and the generative growth stage (anthesis). At the vegetative growth stage the assimilate export from the mildew inoculated 5. leaf of ‘Amsel’ and ‘Rupee’ is decreased; in ‘Asse’, there is no considerable change of assimilate distribution due to infection. At the generative growth stage the assimilate export from the infected flag leaf of ‘Amsel’ is reduced when the fungus, is sporulating. In the cultivar ‘Asse’ the assimilates are bound at the infection site until the seventh day after inoculation, then the transport of assimilates to the ear is increased. In ‘Rupee’ mildew inoculation causes an enhanced assimilate transport to the ear. The changes in assimilate distribution due to mildew inoculation are discussed with respect to the different types of host‐parasite‐interactions and the source‐sink‐activities in the different cultivars.
Cucumber Mosaic Virus on Banana in Crete
Authors: Avgelis A.
Published: May 2008

A virus was isolated from banana plants grown in plastic houses and showing chlorotic striping on leaves and stunting. On the basis of host range symptomatology, aphid transmission and serological tests, it was identified as a strain of cucumber mosaic virus. Infected propagating material was more responsible for the outbreak of the disease than aphids.
Comparison of Three Plant Rhabdovirus Isolates by Two Different Serological Techniques
Authors: Adam G. , Chagas C. M. , Lesemann D.‐E.
Published: May 2008

Three different rhabdovirus isolates, eggplant mottled dwarf virus (EMDV), tomato veinyellowing virus (TVYV) and a hitherto undefined isolate from tomato in Portugal (Tom‐P) were compared by two different serological techniques, immunosorbent electron microscopy (ISEM) and electro‐blot‐immunoassay (EBIA). Antisera were prepared either against purified virus or against partially purified virus preparations extracted by a one‐step procedure. Even the partially purified virus preparations yielded antisera that allowed unequivocal identification of two of the five structural virus proteins, G and N, in EBIA and were suitable for specific trapping of complete virus particles on electron microscope grids.

With both serological techniques identical results were obtained indicating a close serological relationship between the three isolates tested. Cross‐reactions between the G proteins could be deduced from heterologous trapping of complete virus particles in ISEM. The cross‐reactions for the G proteins were substantiated by the EBIA‐results which indicated in addition cross‐reactions between the remaining three major structural virus proteins, N, M1, and M2, but also revealed significant differences in the molecular weights of the G and M1 proteins between TVYV and the other two isolates. The results obtained indicate that Tom‐P is serologically closely related and in respect of protein molecular weights identical to EMDV, and that TVYV is not a separate virus but rather a strain of EMDV.
Involvement of Volatile Substances in Systemic Resistance of Barley Against Erysiphe graminis f. sp. hordei Induced by Pruning of Leaves
Authors: Fujiwara M. , Oku H. , Shiraishi T.
Published: May 2008

Incubation of barley seedlings in a container with seedlings of which primary leaves were pruned induced in the intact seedlings a systemic resistance to the infection by Erysiphe graminis f. sp. hordei. The induced resistance was moreprominent in the primary leaf than in the secondary leaf. Hence, some volative substances released after pruning of barley leaves seem to be responsible for the induced resistance against the powdery mildew fungus.
A Comparative Study of Four Viroids of Plants
Authors: Kryczyński S. , Paduch‐Cichal E.
Published: May 2008

The host‐ranges and the reactions of particular plant hosts to inoculation with severe (s‐PSTV) and mild (m‐PSTV) strains of potato spindle tuber viroid, as well as with chrysanthemum stunt viroid (CSV) and cucumber pale fruit viroid (CPFV) were quite similar. Some minor differences did not exceed the limits of differences noted for the strains of the same plant viroid. Two‐directional crossprotection was noted for each viroid pair when s‐PSTV, m‐PSTV, CSV and CPFV were tested on chrysanthemum cv., ‘Bonnie Jean’ plants. Finally, the relative mobility of RNAs of s‐PSTV, m‐PSTV, CSV and CPFV on 5% polyacrylamide gel was identical, no matter what extraction method from plant material was used. We postulate that these four plant viroids may be regardedas the strains of the same plant viroid “species”.

On the other hand, chrysanthemum chlorotic mottle viroid (ChCMV) appeared to be a quite different plant pathogen. This viroid infected and caused symptoms only in chrysanthemum plants, and was able to infect and induce symptoms on plants which had already been infected with any other viroid studied, and it did not protect chrysanthemum cv. ‘Bonnie Jean’ plants against any of the other viroids. We were not able to locate a ChCMV‐RNA band on polyacrylamide gel.
Das Verhalten einiger pilzlicher Antagonisten in der Rhizosphäre resistenter und anfälliger Gewächshaustomaten
Authors: Bourbos V. A. , Skoudridakis M. T.
Published: May 2008

Action of some fungal antagonists in the rhizosphere of resistant and susceptible tomato plants in the greenhouse

The quantitative presence of the rhizospheric mycoflora fungi: Aspergillus alutaceus, Paecilomyces lilacinus, Penicillium herquei, P. nigricans and Trichoderma viride known for its antagonistic action to many pathogens is essentially differentiated in the two cultivars – the sensitive ‘Early pack’ and the resistant to tracheomycosis ‘GC 204′. It seems that the presence of the cultivar ‘GC 204’ favours the growth of these fungi. The first establishment of the fungi Penicillium chrysogenum and P. funiculosum, which are isolated from both cultivars, in the ‘Early pack’ rhizosphere might facilitate the colonization of this zone by the above mentioned antagonist which is not favoured by the sensitive cultivar. Such a changein the rhizospheric mycoflora of the sensitive cultivar may introduce some resistant to soil borne fungi diseases and open new perspectives of the biological control of these diseases.
Detection of Tomato Ringspot Nepovirus and a Clostero‐like Virus in French Hybrid Vidal 256 Grapevines
Authors: Podleckis E. V. , Corbett M. K.
Published: May 2008

Eight‐ to ten‐year old French hybrid Vidal 256 grapevines in southern Maryland produced berries about one‐third normal size but did not express any obvious leaf symptoms. Electron microscopy of negatively stained tissue‐dip preparations and sectioned material from such vines showed individual and membrane‐associated 28 nm spherical virus‐like particles and closteroviruslike particles. The spherical particles were characterized as an isolate of tomato ringspot virus (TomRSV‐G) that infected a wide range of herbaceous hosts by mechanical inoculation, but did not infect tomato, bean or petunia plants susceptible to the type strain of TomRSV. The closterovirus‐like particles did not react, by immunosorbent electron microscopy, with antisera to grapevine virus A (grapevine stem‐pitting associated virus of Contiet al. 1980) or the 2200 nm Swiss grapevine leafroll closterovirus (Gugleriet al. 1984).
Peroxidase and Poly‐Phenol Oxidase in Brassica juncea Plants Infected with Macrophomina phaseolina (Tassai) Goid. and their Implication in Disease Resistance
Authors: Srivastava S. K.
Published: May 2008

Studies on the peroxidase and poly‐phenol oxidase activity in relatively resistant and susceptible strains of Brassica juncea at sequential intervals after inoculation with different isolates of Macrophomina phaseolina revealed that, fungus infected tissues had relatively higher activities of these oxidative enzymes in comparison to healthy plants, and tissues inoculated with ‘Weakly Virulent’ isolates always exhibited higher activity in comparison to ‘Moderately’, ‘Highly’ and ‘MostHighly Virulent’ isolates. At the early stages of the infection on 6th day, resistant plants showed higher activities in comparison to their susceptible counterparts. Very low activity of these enzymes could be recorded in healthy plants. Findings of this, study indicate the possible involvement of these oxidative enzymes in the resistance of this disease.
Squash Mosaic Virus as the Cause of Melon Veinbanding Mosaic in Iran1)
Authors: Izadpanah K.
Published: May 2008

Melon veinbanding mosaic, a prevalent disease in the Bushehr Province of Iran, is characterized by formation of green veinbanding in varieties of Cucumis melo L. The disease is caused by an isometric virus of about 30 nm diameter. The virus was purified by acid and neutral pH clarification, polyethylene glycol precipitation and differential and density‐gradient centrifugation. The virus formed three zones in the density‐gradient columns. It reacted with a squash mosaic virus (SqMV) antiserumobtained from the United States in agar‐gel diffusion. Likewise, a U.S. isolate of SqMV reacted with the antiserum prepared against the Iranian isolate. The virus was seed transmissible in snakemelon. This is the first report on the field occurrence ofSqMV in Iran. The Iranian isolate appears to belong to the serotype 1 of SqMV.
A Leaf and Fruit Disease of Pandanus conoideus caused by Erwinia carotovora subsp. carotovora in Papua New Guinea
Authors: Tomlinson D. L.
Published: May 2008

A disease of Pandanus conoideus which causes leaf necrosis and fruit rot is reported from Morobe Province of Papua New Guinea. Biochemical, physiological and pathogenicity tests show the causal organism to be a strain of Erwinia carotovora subsp. carotovora. The disease is common on P. conoideus and also affects leaves but not fruit of P. julianettii, another pandanus widely grown in the area.
Detection of Potato Leaf Roll Virus in Intact Sprout Disks by Enzyme‐linked Immunosorbent Assay
Authors: Syller J.
Published: May 2008

Potato leaf roll virus (PLRV) was detected by enzyme‐linked immunosorbent assay (ELISA) when intact sprout, stem or leaf tissue disks were substituted for leaf or tuber extracts as test samples. Absorbance (A405) values increased with increasing number of disks per plate well. Readings with sprout disks were significantly higher than those with disks cut from other plant tissues or with tuber sap. A405 values obtained by using 7 or 5 sprout disks per well were near the maximum oneobtained with leaf sap. PLRV was slightly more efficiently detected by ELISA in light sprout disks than in etiolated sprout ones. When ten out of 34 healthy tubers were replaced by PLRV‐infected ones in the tuber indexing test, the diseased samples werereliably detected with 5 etiolated sprout disks per well. The sprout disk sampling technique should be useful for qualitative evaluation of PLRV infection in sprouted potato tubers without necessity to wound them and using sprouts not long enough for maceration.
A Simple Procedure to Detect a dsRNA Associated with Groundnut Rosette
Authors: Breyel E. , Casper R. , Ansa O. A. , Kuhn C. W. , Misari S. M. , Demski J. W.
Published: May 2008

A low‐molecular weight double‐stranded (ds) RNA [900 base pairs (bp)] associated with groundnut rosette disease can be used as a diagnostic tool. A simple procedure has been developed that is rapid, reliable, and requires only standard electrophoresis equipment and ultraviolet light for detection of nucleic acid bands. Using this procedure, the dsRNA was detected only in groundnut plants with green rosette of chlorotic rosette symptoms. It was not found in uninoculated groundnut plants, in symptomless groundnut plants with groundnut rosette assistor virus, or in groundnut plants infected with several other known groundnut viruses. In studies with northern blots of extracts from rosette‐diseased and healthy plants, 5′‐endlabeled dsRNA only hybridized to a 900 bp dsRNA from diseased plants. The 900 bp dsRNA was not infectious and its origin remains obscure.
The Development of a Host‐Pathogen System for Evaluating Fusarium Resistance in Early Growth Stages of Wheat
Authors: Miedaner T.
Published: May 2008

Controlled environment studies revealed significant genetic variation in resistance of wheat seedlings to Fusarium culmorum by using a new developed test system which affords a reproducible inoculation and a precise measurement of the infection rate. A nutrient solution and a conidial suspension in a defined amount are added to agar after autoclaving and the germinated seed are incubated under sterile conditions. With this in vitro‐culture technique F. culmorum infected the whole root system of all tested plants during 12 days and caused significant reduction of root and shoot dry weights. Therefore, escape reactions, depending on the different rapidity of root development, were eliminated. The loss of root dry matter ranged from 12 to 89 %, thus allowing a selection for Fusarium resistance even in the early developmental stages of wheat.
The Smut Fungi of Hyparrhenia hirta (Gramineae)*
Authors: Vanky K. , Deml G. , Oberwinkler F.
Published: May 2008

The following smut fungi reported from Hyparrhenia hirta were studied: Sporisorium andropogonis, S.bardnonense, S. puellare, and S. transfissum. Two new combinations are proposed: Sporisorium barcinonense (Riofrio) Vanky, and S. puellare (H. Sydow) G. Deml. S. andropogonis and S. puellare have morphologically identical spores but differ in the type of spore germination. While S. puellare germinates by a ramified mycelium, S. andropogonis produces four‐celled basidia forming basidiospores laterally and apically. It appears that S. andropogonis is restricted to Dichanthium ischaemum, and S. puellare to Hyparrhenia hirta. S. harcinonense and S. transfissum, both producing the same type of floral infection, are differentiated by their spore measurements.
Small RNAs Originating from Symptomless and Damaged Spruces (Picea abies L., Karst.) II.
Authors: Köster S. , Beuther E. , Riesner D.
Published: May 2008

A nucleic acid of about 450 nucleotides, called RNA450, was extracted from needles of symptomless and damaged spruces (Picea abies L., Karst.) and was analysed by two‐dimensional gel electrophoresis. The samples originated from 14‐years‐old spruces of two differently exposed forest sections of the same location in the Hils area. Trees of section 65 were symptomless whereas those of section 103 were retarded in their growth and had partly yellow coloured needles.

A new tree was selected for each sampling. Samples were taken at monthly intervals from June 1985 to March 1986, and bimonthly from March to December 1986. The aim of the study is to find out whether the RNA450 indicates the damage of trees in the Hils. The RNA450 was characterized in the accompanying paper (Beutheret al. 1988) as an endogeneous RNA, which is influenced in its concentration by tree damages. A comparison of the RNA patterns of needle extracts from four different needle year classes of symptomless and damaged trees led to the result that the concentration of RNA450 is influenced by season, needle age, and damage. The amplitude of the seasonal changes in the RNA450 level was found to be larger in younger than in older needles and is not influenced by the position of the branch. The period of metabolic activity, as observed on the level of RNA450, is markedly shorter in damaged than in symptomless trees. The usefulness of the RNA450 as a diagnostic test system will be discussed.
A Cucumber Disease Caused by Alternaria alternata and its Control
Authors: Vakalounakis D. J. , Malathrakis N. E.
Published: May 2008

A severe leaf spot disease of cucumber caused by a pathotype of Alternaria alternata (Fr.) Keissler was recorded recently in plastic houses in Crete. Lesions ranged in size of a pin point to over 5 cm in diameter, with necrotic tissue on most of their area and a surrounding yellow zone. The pathogen grew satisfactorily on PDA at temperatures between 5 °C–40 °C and spore germination occurred in the range less than 10 °C to over 37 °C. Optimum temperature in both cases was near 26 °C. Of,13 fungicides tested in vitro, sodium omadine, etem, dichlofluanid, captan and folpet were the most inhibitory on spore germination, and iprodione, sodium omadine and dichlofluanid on mycelial growth. Of 25 fungicides applied on two leaf cucumber plants 24 h before inoculation, maneb, etem, dichlofluanid and chlorothalonil were the most effective. When the last fungicides, plus mancozeb, were applied 24 h after inoculation only maneb was effective. In greenhouse experiments, iprodione, prochloraz‐manganese‐complex, chlorothalonil, dichlofluanid, guazatine, maneb and etem were the most effective for disease control, while mancozeb was less effective. The local cucumber cv. Knossos and the Dutch F1 hybrids Evadan, Frella, Herta, Malfa, Mazourka, Pepinex 69 and Renova were all susceptible to infection.
A Strain of Eggplant Mosaic Virus Causing a Severe Disease of Tomato in Argentina
Authors: Gracia Olga , Koenig Renate , Feldman J. M. , Barradas Maria M.
Published: May 2008

A virus causing a severe disease of tomatoes in Argentina was identified as a strain of eggplant mosaic virus (EMV). It resembles the type, Abelia latent and various Andean potato latent strains of EMV in its host range and its transmissibility at allow rate by Epitrix sp. It differs from these strains, however, serologically and in some of its cytopathic effects. In serological agar gel double diffusion tests it proved to be closely related to the tomato white necrosis isolate of EMV studied by Barradas (1983) in Brazil.
Isolation of Carnation Ringspot Virus from a Canal Near a Sewage Plant: cDNA Hybridization Analysis, Serology and Cytopathology
Authors: Koenig R. , An D. , Lesemann D.‐E. , Burgermeister W.
Published: May 2008

A small water sample of only 60 ml from the Oker Aue canal near Braunschweig was ultracentrifuged. The resuspended pellet was rubbed on Chenopodium quinoa leaves which responded with the formation of almost 200 local lesions. The virus causing these lesions was identified as carnation ringspot virus (CarRSV) by means of dot blot hybridization using random‐primed cDNAs to the viral nucleic acids and by means of serology. Northern blot analysis revealed that the two RNA species of the virus which consisted of c. 3.7 and 1.5 Kb, respectively, have little or no base sequence homology. In immunoelectrophoresis at pH 7.0 the virus migrated towards the cathode. The isometric particles were 33 nm in diameter, round to slightly angular in outline, and showed a distinct granular or knobly surface structure. Virus particles occurred in the cytoplasm, nuclei, and vacuoles of infected cells which in addition contained amorphous granules in the cytoplasm and/or proliferated endoplasmic reticulum. Heavily, affected cells were necrotized and contained large virus particle aggregates which sometimes were crystallized.

CarRSV is the third carnation virus, after carnation mottle and carnation Italian ringspot viruses, which was identified in a natural water.
Peroxidase Activity as a Marker in Greening Disease of Citrus for Assessment of Tolerance and Susceptibility
Authors: van Lelyveld L. J. , van Vuuren S. P.
Published: May 2008

The possible connection between peroxidase activity and citrus species and cultivars was investigated in relation to tolerance and susceptibility to greening disease.
Isolation and Culture of Corn Stunt Spiroplasma in Serum‐Free Medium
Authors: Alivizatos A. S.
Published: May 2008

A serum‐free medium (medium A6), supports the primary isolation and cultivation in vitro of corn stunt spiroplasma (CSS). The growth characteristics of CSS in A6 medium are similar to those in the conventional serum dependent, ketoglutarate sorbitol medium (SMK).
Cellulolytic Activity of Three Fusarium culmorum (W. G. Sm.) Sacc. Isolates Pathogenic towards Wheat Seedlings
Authors: Mańka Malgorzata
Published: May 2008

Fusarium culmorum isolates pathogenic to wheat (severely, medium and weakly pathogenic) proved to be producers of endo‐1,4‐β‐glucanase and exo‐1,4‐β‐glucanase. The activity of the latter enzyme was low. There was no correlation between the activities in vitro of the two enzymes and pathogenicity of the isolates.
Purification and Electron Microscopy Studies of a Probable Potyvirus from Polianthes tuberosa L.
Authors: Horner MaryB. , Pearson M. N.
Published: May 2008

A partial purification procedure is described for a flexuous filamentous virus from leaves of the ornamental crop tuberose (Polianthes tuberosa L.) exhibiting mottle symptoms. Particular problems associated with the purification included particle aggregation and the highly viscous nature of the plant sap. The former difficulty was partially alleviated by the addition of 1.0 M urea to the extraction buffer and the latter by treatment of the extract with cellulase. The mean virus particle length from negatively stained leaf dips was 742 nm (SD = 54) which is characteristic of viruses belonging to the potyvirus group. In addition, electron microscopy of thin sections of infected leaf tissue demonstrated the presence of several types of inclusion bodies similar in appearance to inclusions previously described in association with potyvirus infections in other plants.
Levels of Airborne Botrytis cinerea Conidia Trapped Among Pepper (Capsicum annuum L.) and Eggplant (Solanum melongena L.) Crops Cultivated in Polyethylene Greenhouses on the Málaga Coastal Plain (Southern‐Spain)
Authors: López‐Herrera C. J.
Published: May 2008

The levels of B. cinerea conidia in the air of greenhouses with pepper or eggplant crops at El Morche (Málaga, Spain) were studied during the 1981–82 and 1982–83 growing seasons.

The number of conidia collected, the temperatures and relative humidities recorded during different periods were analyzed and fitted to different regression models. Several types of transformation were made to straighten the curves.

In both seasons, the regression analyses of the pepper crop data showed no statistical significance, but those for eggplant crops did. The levels of significance for the eggplants were good and those of the 1981–82 experiment were the best.

During the 24 h period prior the conidia collection, there was a negative correlation between temperatures measured 6 and 8 h prior to conidia sampling and the number of conidia collected. When the 2nd pair of variables was used, B. cinerea conidia collections were less the longer the periods of temperatures between 20 and 30°C with relative humidities above 70%.

This type of information would facilitate a more rational physical and chemical control of the disease in greenhouse vegetable crops to prevent or reduce crop losses.
Pterocarpan Accumulation in Pod Infection‐droplets and Pod Tissues of Phaseolus vulgaris Inoculated with Colletotrichum lindemuthianum1
Authors: Cruickshank I. A. M. , Smith M. M.
Published: May 2008

Following inoculation of pods of several cultivars of French bean (Red Kidney Selections W 243, 244, 245), with Colletotrichum lindemuthianum (Sacc. & Magn.) Bri. and Cav. ANZ races 1 and 2, phaseollin, phaseollidin and 6‐α‐hydroxyphaseollin were estimated in infection‐droplets and tissue extracts by u.v. spectrophotometry and HPLC. The examples represented both compatible and incompatible cultivar‐race interactions and confirmed a positive correlation between degree of incompatibility andphaseollin concentration or content. The data supported the concept that a phytoalexin index may be of value in selecting for disease resistance or studying the quantitative inheritance of phaseollin in studies of anthracnose resistance in French beans.Concentrations of phaseollidin and 6‐α‐hydroxyphaseollin were low and were not correlated with degree of compatibility of cultivar‐race interactions. The evidence did not support the putative role of 6‐α‐hydroxyphaseollin as an in planta degra, dative phaseollin metabolite associated with French bean –C. lindemuthianum compatible interactions.
Changes in pH and the Production of Organic Acids During Colonization of Tomato Petioles by Botrytis cinerea
Authors: Verhoeff K. , Leeman M. , van Peer R. , Posthuma L. , Schot Nelleke , van Eijk G. W.
Published: May 2008

After inoculation of petiole stumps of tomato plants with a tomato isolate of B. cinerea, a transition zone between water‐soaked and apparently healthy tissue became clearly visible. Hyphal colonization occurred up to approximately 2 mm beyond this zone. In the colonized tissue the pH values were lower than in the healthy tissue. In the region with most of the tips of the advancing hyphae, however, pH values were slightly, but consistently, higher. In the colonized tissue concentrations of oxalic, citric and succinic acid were higher than in the tissue of healthy, non‐inoculated petioles. In vitro this isolate of B. cinerea produced citric, malic and succinic acid. Oxalic acid, however, could not be detected. In media enriched, with citric or malic acid, mycelial production was higher than in media without this enrichment.
No Evidence of Direct Superoxide Anion Effect in Hypersensitive Death of Pseudomonas syringae Van Hall in Tobacco Leaf Tissue1
Authors: Minardi Paola , Mazzucchi Umberto
Published: May 2008

The hypothesis of superoxide anion generation as a direct bactericidal mechanism exercised by hypersensitive tobacco leaf tissue against an incompatible phytopathogenic pseudomonad was tested.

The detection of O2− was made directly by reducing Cytochrome c and by producing nitrite from hydroxylamine chloride and indirectly by measuring the death of endophytic bacteria in the presence of superoxide dismutase.

At 4 h and 6 h the low net specific reduction of Cytochrome c in the hypersensitive tissue was not confirmed by the specific production of nitrite. At the same time active superoxide dismutase did not give significant protection to the incompatible bacteria as compared to inactive superoxide dismutase. The protection provided by active superoxide dismutase as compared with the controls (bovine serum albumine treated tissue and non‐treated tissue) at 4 h and at 6 h was not correlated to its superoxide anion scavenger activity.

The results indicated that the death of the incompatible pseudomonad during the hypersensitive reaction was not directly linked to O2− generation.
Host Ranges, Serology and Cytopathology of Eggplant and Tomato Strains of Eggplant Severe Mottle Virus, a New Potyvirus from Nigeria
Authors: Ladipo J. L. , Lesemann D.‐E. , Koenig Renate
Published: May 2008

Two potyvirus isolates from the eggplant (Solanum melongena L.) cultivars ‘Ex Benin’ and ‘Ex Jos’, respectively, in Nigeria proved to be almost identical in host range, symptomatology and reactivity with antisera to various potyviruses. In eggplant they caused a severe systemic mottle, blistering and malformation of leaves and an abnormal serration of the leaf margins. A potyvirus isolate from tomato showing mosaic symptoms was similar, but not identical to the eggplant isolates. In the slide, precipitin test the serological differentiation indices were between 1 and 3 for the eggplant and tomato isolates. In the immunoelectron microscopical decoration test all three virus isolates showed some reactivity with antisera to the following potyvir, uses: dioscorea green banding mosaic, groundnut eyespot, a mungbean isolate of peanut stripe, pepper veinal mottle, telfairia mosaic and a tomato isolate from Taiwan. No reactions were observed with antisera to other potyviruses. Cytopathogenic effects w,ere similar for all three isolates in the arrangement of virus particles, the structure of the cylindrical inclusions and the occurrence of clusters of small vesicles. However, other cytological alterations like accumulations of rod‐shaped aggregates of,granular material, formation of giant mitochondria, degeneration of mitochondria and occurrence of a nucleolar inclusion differentiated the isolates.
Correlation Between Induced Resistance and Host Fluorescence in Barley Inoculated with Erysiphe graminis
Authors: Thordal‐Christensen H. , Smedegaard‐Petersen V.
Published: May 2008

Resistance was induced in barley by virulent and avirulent Erysiphe graminis f. sp. hordei and by E. graminis f. sp. tritici. The diameters of fluorescent haloes and papillae at the site of the primary germ tube of the inducers were larger until 12 hours after inoculation with E g. f. sp. tritici than in the corresponding periods after inoculation with E. g. f. sp. hordei. Fluorescence at the site of appressorial lobes of the inducers developed, gradually from 10 and 12 hours after inoculation with E. g. f. sp. hordei and E. g. f. sp. tritici, respectively. Penetration success of single infection units of the challenger was reduced in cells with inducer fluorescence, suggesting that resistance is principally localized to cells previously attacked by the inducer. But penetration success was independent of the average distance to the ten nearest inducer fluorescences, and penetration failures did also occur in cells without inducer fluorescence, suggesting that the induced resistance to some extent is translocated to other epidermal cells. The average diameter of the fluorescent papillae at the site of unsuccessful challenger infection units increased as a result of induced resistance.
Effect of Foliar Applications of Fungicides on the Phylloplane Mycoflora and Fungal Pathogens of Guava
Authors: Pandey R. R.
Published: May 2008

Colletotrichum gloeosporioides and Pestalotia psidii were found to be the dominant pathogens causing leaf spots and fruit diseases of guava. Effects of two fungicides in rainy (wet) and four fungicides in the winter (dry and cool) seasons separately, in concentrations of 500, 1500 and 3000 mg a.i. I−1 (ppm) have been investigated on the pathogens and on composite phylloplane fungi. Benomyl was found most effective against the population of pathogens and checked disease development. However, it was effective only at the schedule of three successive foliar applications. The application of captan did not check P. psidii as effectively as benomyl but it had a marked adverse effect on many of the phylloplane fungi. A signif, icant decrease in the number of fungal species colonizing mancozeb and dichlone‐treated leaves was observed. Lesion measurement and spore germination tests against both pathogens following chemical treatments in vivo and in vitro respectively have also been made.
Pathogenicity of Geographic Isolates of Fusarium oxysporum from Crucifers on a Differential Set of Crucifer Seedlings
Authors: Bosland P. W. , Williams P. H.
Published: May 2008

Pathogenicity tests with 103 isolates of Fusarium oxysporum from crucifers worldwide were conducted using a standard set of six differential crucifer cultivars. Based on their reaction to the standard differentials, all isolates could be grouped into the five major pathotypes in the three formae speciales, f. sp. conglutinans. f. sp. raphani and f. sp. matthioli. When two additional crucifers, Brassica nigra and B. campestris were added to the differe, ntial set, and the reactions of the host differentials were analyzed, an increased range of virulence profiles was observed, implying the existence of more virulence factors in the F. oxysporum population. An isolate from the U.S.S.R., was identified with virulence capable of overcoming dominant monogenic “type A” resistance in Brassica oleracea suggestive of a potentially new location for this pathotype.
Isolation of a Plasmid from Xanthomonas campestris pv. vignicola
Authors: Ulaganathan K. , Mahadevan A.
Published: May 2008

A modified method is described for isolating high yields of plasmids without chromosome contamination from Xanthomonas campestris pv. vignicola (X. c. pv. vignicola), the causal agent of blight disease in Vigna species and also in Phaseolus vulgaris. Applying this method a plasmid of X, c. pv. vignicola was detected representing an estimated molecular weight of 95 megadaltons. Heat curing of the strain revealed that the detected plasmid had no effecton virulence but seemed to influence colony morphology.
Systemic Acquired Resistance Induced in Tobacco Plants by Localized Virus Infection Does Not Operate Against Challenging Viruses That Infect Systemically
Authors: Pennazio S. , Roggero P.
Published: May 2008

Localized infections produced by tobacco necrosis virus (TNV) or tomato mosaic virus (ToMV) in White Burley tobacco induced a systemic acquired resistance in upper, uninoculated leaves. This resistance was effective against challenge infection by TNV or ToMV but not by potato virus Y, necrotic strain (PVYn), tobacco mosaic virus (TMV) or tobacco rattle virus (TRV), viruses giving systemic infections.

Systemic acquired resistance against TNV or ToMV was expressed as a reduction in lesion size but not in viral antigen content of the resulting necrotic local lesions. The acquisition of resistance was concurrent with an increased capacity of the resistant leaves to convert 1‐aminocyclopropane‐1‐carboxylic acid into ethylene.

Systemic acquired resistance was ineffective to contrast or minimize in whatever way the systemic challenge infection produced by PVYN, TMV or TRV. Severity of symptoms and virus multiplication did not differ in resistant leaves from controls. This result does not allow any optimistic promise on possible application of the systemic acquired resistance against severe viral diseases of crops.
Involvement of Epicatechin in Cultivar Susceptibility of Avocado Fruits to Colletotrichum gloeosporioides after Harvest1
Authors: Prusky D. , Kobiler I. , Jacoby B.
Published: May 2008

Avocado cultivars were defined as susceptible and resistant to Colletotrichum gloeosporioides depending upon the length of the incubation period of the disease after fruit softening. In the susceptible cultivars Fuerte, Horshim, Vurtz, Rincon, and Benik, epicatechin concentration of the peel decreased to 60‐130 μg.g−1, fr. wt. at fruit softening and symptoms appeared on the same or one day later. In the resistant cultivars Hass, Nabal, Netaim and Pinkerton, epicatechin concentration was still 632–1740 μg.g−1 fr. wt. when fruit softening and symptoms appeared only 4‐10 days later. When susceptible Fuerte fruits became soft the concentration of the antifungal compound 1‐acetoxy‐2‐hydroxy‐4‐oxo‐heneicosa‐12,15 diene, had decreased to 120 μg.g−1 fr. wt. and symptoms appeared. In resistant Hass fruits, the antifungal diene was still 238 μg.g−1 fr. wt. at fruit softening; and it had further decreased to 159 μg.g−1 fr. wt. when symptoms appeared, four days later. A modified atmosphere and 0.2 M CaCl2 infiltration both delayed softening of Fuerte fruits; but symptom appearance on these fruits was related to diene decrease and not to fruit softening.

The results are discussed in relation to the hypothesis that the susceptibility of avocado cultivars to post‐harvest decay by C. gloeosporioides is related to the degradation of the antifungal diene, catalyzed by avocado lipoxygenase, the activity of which is regulated by the decline of its inhibitor epicatechin.
Further Studies on Cynara Rhabdovirus
Authors: Rana G. L. , Franco A. di , Galasso I.
Published: May 2008

Cynara rhabdovirus (CyRV) was isolated from symptomless artichoke plants in southern Italy using Nicotiana langsdorffii as susceptible host and immune serum to artichoke latent virus to eliminate this virus from inoculum. CyRV can infect several solanaceous species, has thermal inactivation point of 40‐45°C, dilution end point between 10−2 and 10−5 and longevity in vitro at 4 and 20°C of 4‐5 days and 6‐24 h, respectively. It was purified and used for preparing antisera with homologous titre varying from 1: 16 to 1: 64. In decoration tests, the virus did not react against antisera to eggplant mottled dwarf virus (EMDV) and its antiserum did not decorate ivy vein clearing virus (IVCV). Ultrastructural aspects of CyRV infection in Datura stramonium and Nicotiana glutinosa were very like those described for the same virus in the past except for presence of longer virions which were often encountered in infected cells during this study.