bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of a Tymovirus Isolated from Anagyris foetida as a Strain of Scrophularia Mottle Virus
Authors: Rana G. L. , Castellano M. A. , Koenig R.
Published: May 2008

A virus isolated from Anagyris foetida and infecting species in the Leguminosae and Solanaceae had typical properties of a tymovirus. It sedimented as two components (49 S and 103 S) and induced the formation of double membrane‐bounded invaginations in the chloroplasts of infected cells. Large numbers of ‘empty shells’ were found in the nuclei. The coat protein had a molecular weight of c. 20.000 and the RNA consisted of c. 5500 nucleotides. Crystallization of the virus in laminal crystals could be achieved by precipitation with 10 % polyethylenglycol 6000 and 1 % NaCl. Serologically, the virus was closely related to Scrophularia mottle, Ononis yellow mosaic and Plantago mottle viruses. The four viruses which all infect leguminous hosts are separated by serological differentiation indices which are mostly between 1 and 3. It is therefore suggested that they all should be considered as strains of the same virus which for reasons of priority should have the name Scrophularia mottle virus (ScrMV). The proposed Anagyris strain clearly differs from the Scrophularia mottle, Ononis yellow mosaic and Plantago mottle strains of ScrMV in host range, symptomatology, electrophoretic mobility serological properties and some cytopathogenic effects. It is not clear why the Anagyris strain infects A. foetida systemically in nature, but only locally under greenhouse conditions.
Sensibilité du Melon àSphaerotheca fuliginea en Fonction de L'Etage Foliaire
Authors: Ferriere Halina , Molot P. M.
Published: May 2008

Effect of leaf position on the susceptibility of melon plants to artificial infection with powdery mildew, Sphaerotheca fuliginea

The leaf position of melon plants seems to play a role on their susceptibility when they are artificially infected with powdery mildew Sphaerotheca fuliginea. The cotyledons are generally very susceptible, while the first leaf relatively resistant; the susceptibility again continues up to the 4th–5th leaf (but less susceptible than the cotyledons) and then after it decreases; these results can be obtained on plants in greenhouse or on detached leaves in Petri dishes.

From this observation, we think that the screening of melon genotypes for resistance to powdery mildew can be evaluated neither on the cotyledons which are very susceptible nor on the first leaf which is resistant, but on the third leaf which is moderately susceptible. In fact, there is a good correlation between the reaction of the third leaf and the resistance or susceptibility of genotypes.
Resistance of Tobacco to Thielaviopsis basicola under Tissue Culture Conditions and Increased Susceptibility after Transformation with Agrobacterium tumefaciens T‐DNA
Authors: Gasser R. , Kern H. , Défago G.
Published: May 2008

Tobacco callus cultures from a Thielaviopsis basicola (Berk. et Br.) Ferraris resistant cultivar were less severely colonized than callus cultures from susceptible cultivars by the pathogen at all concentrations of kinetin and α‐indoleacetic acid tested. However, at concentrations where these substances influenced the morphology of the callus cultures they also influenced the degree of colonization by the fungus. Incorporation of T‐DNA of Agrobacterium tumefaciens induced susceptibility in tissue culture of the resistant cultivar but did not significantly modify the reaction of the susceptible cultivar tested.
Penetration of Hyphae of Sclerotinia sclerotiorum by Coniothyrium minitans Without the Formation of Appressoria
Authors: Huang H. C. , Kokko E. G.
Published: May 2008

In a study using scanning electron microscopy (SEM), the mode of hyperparasitism of Coniothyrium minitans on its host Sclerotinia sclerotiorum was investigated. The SEM micrographs confirm previous reports, from light microscopic studies, that hyphal tips of C. minitans invade the host hypha by direct penetration, without developing appressoria, and that indentation of the host cell wall at the point of penetration is often evident. There is no functional distinction between amain branch and a side branch hypha of the hyperparasite and tips of either type of hyphae are capable of invading host hyphae by direct penetration.
Characteristics of Inhibition of a Taiwanese Soil Suppressive to Fusarium oxysporum f. sp. raphani
Authors: Huang J. W. , Sun S. K. , Ko W. H.
Published: May 2008

Germination of nutrient‐amended chlamydospores of the three formae speciales of Fusarium oxysporum tested were inhibited in a suppressive soil collected from central Taiwan. The suppressive soil released a volatile substance when moistened with alkaline solution. The inhibition spectrum of the volatile substance was different from that of the suppressive soil. The inhibitory effect of the suppressive soil was greatly reduced when it was heat‐treated for 30 min at 40°C or higher. The inhibitory effect of the heat‐treated suppressive soil was restored after infestation with 1% conducive or suppressive soil for 14 days. However, infestation of heat‐treated conducive soil even with 1% suppressive soil did not render it suppressive. Amendment of suppressive soil with rose bengal, streptomycin or Rubigan completely or partially reduced the inhibitory effect. Increasing the total population of indigenous microorganisms in conducive soil by amendment with rice germ or soybean meal to about the same level as that in suppressive soil did not render it suppressive. Results suggest that a combination of biotic and abiotic factors is responsible for the inhibitory effect of the suppressive soil.
Suppression by Zygorrhynchus moelleri of Growth and Sclerotium Production by Rhizoctonia solani and Sclerotinia sclerotiorum
Authors: Brown Averil E.
Published: May 2008

As indicated by reduced cellulolysis, Zygorrhynchus moelleri suppressed mycelial growth in Rhizoctonia solani and Sclerotinia sclerotiorum. Sclerotium production by both pathogenic fungi was also reduced by Z. moelleri in dual sand‐oatmeal cultures. The viability of sclerotia produced by S. sclerotiorum, but not those produced by R. solani, was greatly reduced. Sclerotium production by S. sclerotiorum on celery and tomato segments was reduced to a much greater extent when Z. moelleri was applied to the plant tissue 24 h before the pathogen than when applied at the same time or 24 h after the pathogen.
Interaction Between Pratylenchus coffeae and Pythium aphanidermatum and/or Rhizoctonia solani on Chrysanthemum*
Authors: Hasan Abul
Published: May 2008

The interaction between Pratylenchus coffeae and Pythium aphanidermatum and/or Rhizoctonia solani on chrysanthemum and the influence of farmyard manure (FYM) on it was studied under pot conditions. The disease caused by P. aphanidermatum or R. solani was significantly high at varying inoculum levels of Pratylenchus coffeae. The severiy further increased when nematode infected plants were inoculated with both the fungi together. Organic manuring also influenced the disease severity which was greatest in soils containing 200% organic manure.

The nematode population significantly increased in presence of R. solani, decreased in presence of P. aphanidermatum and remained unaffected when both the fungi occurred together around the plants. The nematode population was greatly reduced in soils containing 200% organic manure.
Viability Tests for Thick Walled Fungal Spores (ex: Oospores of Peronospora manshurica)
Authors: Roongruangsree U‐Tai , Kjerulf‐Jensen C. , Olson L. W. , Lange L.
Published: May 2008

Oospores of Peronospora manshurica, the causal agent of soybean downy mildew, were stained by a variety of techniques. TTC (tetrazolium chloride) and NBT (nitroblue tetrazolium chloride) primarily stained oospores which were cytologically abnormal and appeared degenerating. Cytological normal oospores were not stained by these compounds presumably because the dyes were excluded from the oospore cytoplasm by the oospore wall or the plasmalemma. Strong autofluorescence of dead/degenerating oospores in the FDA test (fluorescein diacetate) made scoring of the oospore viability by this technique unreliable. Phloxine B was found in a consistent way to stain the degenerating oospores and a small proportion of the oospores which by light microscopic, observations could not be scored cytologically abnormal. Control experiments with live and dead cells of yeast (Saccharomyces cerevisiae) confirm that phloxine B is excluded from live cells and dead cells become stained. The presumed mode of action is that the semipermeability of the plasma membrane of live cells excludes the stain. The phloxine B test described here appears a promising technique for the determination of oospore viability of P. manshurica.
Irregular Occurrence of Rhabdoviruslike Particles in Tissues of Fragaria vesca Plants Infected with Strawberry Crinkle Virus
Authors: Converse R. H. , Schaper Ulrike
Published: May 2008

When evaluated by electron microscopy, rhabdoviruslike particles (RLP) were found most frequently in petioles, less frequently in midribs, and not at all in roots or petals of Alpine strawberry plants leaflet graft‐inoculated with strawberry crinkle virus (SCV). In graft‐inoculated plants RLP were found only in mesophyll and phloem parenchyma cells and in sieve tubes. Numbers of RLP detected were highest within one week of the onset of symptoms, decreased with time, and were extremely variable, both among identically treated Alpine seedlings that showed similar crinkle disease symptoms and within Alpine clones. Through electron microscopy we were not able to predict if a given petiole sample from a graft‐inoculated Alpine plant showing typical symptoms of crinkle disease would have no, moderate, or many RLP. The percentage of Alpine plants developing crinkle symptoms after leaflet graft inoculation with symptom‐bearing leaves from a crinkle source was higher in summer than in winter. It was not increased after the source plants had broken dormancy in the spring, compared to plants kept vegetative all winter, and was not dependent on the length of time a symptom‐bearing source plant had been infected. When symptomless leaves from SCV‐infected Alpine plants were grafted to healthy Alpine indicator plants, no symptoms developed on the latter.
Screening for Resistance to Blackleg Phoma lingam (Tode ex Fr.) Desm. within Brassicaceae
Authors: Sjödin C. , Glimelius K.
Published: May 2008

Ninety‐six accessions within the Brassicaceae were inoculated with a wide range of isolates of Phoma lingam and screened for resistance. Initially, seedlings were sprayed with a spore suspension. The material with the highest level of resistance according to the seedling test was further inoculated with pycnospores in cotyledons, adult leaves and stem bases. All representatives with resistance at the cotyledon stage were found to be resistant at the adult, too. A large variability invirulence was found among the different isolates of the pathogen demostrating the importance of using a broad spectrum when screening for resistance. An evaluation based on the response to 17 different P. lingam isolates revealed that five accessions of B. juncea, two of B. nigra and two of B. carinata could be classified as resistant. Although all these representatives contain the B genome of Brassica, there were other accessions with the B genome that were sensitive.
Biological Activity of Four Antifungal Compounds in Immature Avocado
Authors: Sivanathan S. , Adikaram N. K. B.
Published: May 2008

Anthracnose caused by Colletotrichum gloeosporioides in ripe avocados originates as latent infections in the immature fruits. Concentrated ether extract of the peel of apparently healthy, immature avocados when bioassayed on thin layer chromatographic plates with conidia of either Cladosporium cladosporioides or C. gloeosporioides produced four inhibition areas at Rf 0.30, 0.32, 0.70 and 0.75 (these were denoted as AvIV, AvIII, AvII and AvI respectively). A hot chloroform extract was partitioned on a silica gel column and the four antifungal compounds were separated. Spectroscopic data revealed that one of these compounds, AvII, was similar to cis‐l‐acetoxy‐2‐hydroxy‐4‐oxo‐heneicosa‐12,15‐diene and another (AvIV) was a long chain saturated compound comprising hydroxyl group(s) having molecular weight of 268. Toxicity of AvII to C. gloeosporioides was 2 times that of AvIV and 6.5 and 7.5 times that of AvIII and AvI respectively. The amounts of these four antifungal compounds increased gradually during fruit development and reached their maxima at harvest. The concentration of AvI, AvII, AvIII and AvIV was 1300, 920, 1050 and 780 μg/g fresh peel respectively in the fruit at harvesting maturity. The amount of AvII and AvIV decreased to 53 and 64 μg/g fresh peel respectively in the fruit at the ripe stage at which neither AvI nor AvIII was detected. This took place in coincidence with the onset of progressive lesion development by the fungus.
Behaviour of Phytophthora cinnamomi Zoospores on Roots of Four Avocado Cultivars
Authors: Aveling Theresa A. S. , Rijkenberg F. H. J.
Published: May 2008

Scanning electron microscopy was used to study the behaviour of Phytophthora cinnamomi zoospores on the roots of three tolerant avocado cultivars. Duke 7, G6 and Martin Grande, and a susceptible Edranol cultivar. Zoospores were attracted to the region of cell elongation and encysted on the roots of all cultivars studied. Adhesion of the zoospores appeared to be aided by root slime. Cysts usually produced one germ tube which penetrated the root directly, or formed an appressorium‐like swelling before penetration occurred. Extensive growth of germ tubes occurred where zoospores germinated some distance behind the region of elongation. Cysts germinating behind this region often formed branched germ tubes and more than one appressorium‐like swelling. There were no clear differences in the type of pre‐penetration structures, formed by zoospore cysts, on the roots of the different avocado cultivars.
Messung von Merkmalen der quantitativen Scharkaresistenz der Pflaume und Nachweis ihrer Wechselbeziehungen
Authors: Kegler H. , Kleinhempel H. , Meyer U. , Berka K. , Grüntzig Maria
Published: May 2008

Measurement of the characteristics of the quantitative resistance in plum to the plum pox virus and evidence for their interrelations

Two plum clones, with different degrees of susceptibility towards the plum pox virus (PPV), were inoculated with either a weakly or strongly pathegonic strain of PPV. The symptoms which developed in the older leaves (i. e. the 3rd to 5th basal leaves) were measured by visual rating as well as with the aid of a UV‐VIS‐spectralphotometer SPECORD M 40. Additionally, the relative virus concentrations in these leaves were determined by ELISA. Significant differences were established between the infected leaves of the PPV‐sensitive and PPV‐resistant plum clones, irrespective of the method of measurement. The values recorded for the weakly and strongly pathogenic PPV strains were significantly different only with the PPV‐sensitive clone.

A significant correlation was established between the visual ratings and the colormetrical values or the ELISA‐values, as well as between the individual colormetrical values a, L and b. In the system plum‐PPV, the b‐values are the most important in the evaluation of the severity of the symptoms and in the qualitative colour changes.
The Disease Cycle of Mango Malformation Induced by Fusarium moniliforme var. subglutinans and the Curative Effects of Mangiferin‐Metal Chelates
Authors: Chakrabarti D. K. , Ghosal S.
Published: May 2008

Evidence is presented to suggest that the bunchy top, die‐back, abnormal inflorescence and blossom blight disease of Mangifera indica are interlinked and can be expressed as a disease cycle in mango malformation. The morphological and biochemical connections among these symptoms, induced by Fusarium moniliforme var. subglutinans Wollenw. and Reink., are appraised. Partial control of the mango malformation has been accomplished by spraying the diseased parts with mangiferin‐Zn2+ and mangiferin‐Cu2+ chelates. The salutory effect of niangiferin‐metal chelates is evidenced by the revival of normal balance of mangiferin and the micronutrients in the diseased parts, dechne in the fungal population and emergence of healthy shoots.
Fluorescent Pseudomonas Isolates Pathogenic on Witloof Chicory Leaves
Authors: Van Outryve M. F. , Gosselé F. , Joos H. , Swings J.
Published: May 2008

Nineteen phytopathogenic fluorescent Pseudomonas isolates were isolated from diseased witloof chicory (Cichorium intybus L. var. foliosum Hegi). They were compared with six Ps. fluorescens strains from culture collections, using SDS‐PAGE of total cell proteins. The fluorescent pseudomonads examined showed seven different fingerprint types. The major group of phytopathogenic fluorescent pseudomonas revealed a fingerprint type which was frequently found on healthy chicory roots and leaves too. Some, but not all, of the isolates from healthy plants produced typical disease symptoms upon artificial inoculation of etiolated chicory leaves. Infectivity titrations showed a reduced efficiency of the latent pathogen PGSB‐7228 to cause disease symptoms on the chicory leaves. The virulence of the latent pathogen is induced in the presence of wounded chicory tissue.
The Occurrence of Citrus Canker Disease in United Arab Emirates (U.A.E.)
Authors: El‐Goorani M. A.
Published: May 2008

Citrus canker disease caused by Xanthomonas campestris pv, citri is reported on lime in the present study for the first time in United Arab Emirates. The disease was found only on lime in 32 orchards out of 4456 citrus orchards inspected during 1984–85. The citrus canker organism in U.A.E. has a host range similar to “A” strain.

Copper hydroxide was significantly superior to all other treatments in decreasing the incidence of citrus canker disease that developed on inoculated lime seedlings. Streptocycline, Kasumin, copper oxychloride and Bordeaux mixture were not effective in reducing the incidence of the disease.
A Note on the Limitations of Identifying Soft Rot Erwinias by Temperature Tolerances and Sensitivity to Erythromycin on a Pectate Medium
Authors: Janse J. D. , Spit B. E.
Published: May 2008

Forty‐five erwinia strains from 14 different hosts have been tested lor growth on a crystal violet pectate medium with or without 70 μ/ml erythromycin at 27, 33.5 and 37°C. On the basis of positive data in the literature it was tried to identify the strains as Erwnia carotovora subsp. atroseptica, E. carotovora subsp. carotovora or E. chrysanthemi using this method.

It appeared that relatively few strains reacted differentially, apparently due to strain variation (all strains were identified also by biochemical and physiological tests). The conclusion is that for a reliable identification of field isolates of soft rot crwinias other (biochemical, physiological and serological) methods have to be applied.
Induction of Resistance in Tobacco Leaves to Tobacco Mosaic Virus by Dodecylbenzenesulfonate
Authors: Hellwald K. H. , Buchenauer H.
Published: May 2008

Application of dodecylbenzenesulfonate (DBS) to half leaves of Nicotiana tabacum cv. Xanthi nc. before TMV inoculation resulted in a marked decrease in lesion number and size as well as in virus content of the lesions in the untreated half leaves. Systemic induction of resistance in untreated leaves of the plants was not detected.
Hyperparasitischer Angriff von Epicoccum purpurascens auf den biotrophen Kontakt‐Mykoparasiten Gonatobotrys simplex
Authors: Urbasch I.
Published: May 2008

Hyperparasitic attack of Epicoccum purpurascens on the biotrophic contact mycoparasite Gonatobotrys simplex

The in vivo‐ and in vitro‐hyperparazitation of Gonatobotrys simplex (Gs) by Epicoccum purpurascens (Ep) is presented. Ep, showing positive tropism, grows toward the host fungus Gs. After contact Ep penetrates especially the Gs‐conidia, more rarely germ tubes and the mycelium.

Two types of penetration can be distinguished: 1) direct penetration and 2) penetration after previous formation of appressoria.

On this attack Gs reacts with local cell wall appositions (papillae), which mostly can be pierced by the hyperparasite. At the advanced state of parasitism the host fungus finally dies.
Decay of Sclerotia of Botrytis cinerea by Trichoderma spp. at Low Temperatures
Authors: Köhl J. , Schlösser E.
Published: May 2008

In vitro, tests were conducted at 10°C and 5°C against sclerotia of Botrytis cinerea with 58 isolates of Trichoderma spp., highly antagonistic at 24°C but differing in their cold tolerance. Some isolates macerated and colonized sclerotia even at 5 °C. With 19 isolates of Trichoderma spp. less than 10 % of the sclerotia remained viable after 42 d at 5 °C.

Conidia ol some Trichoderma spp. germinated at 5 °C within a few days and reached germination rates higher than 80 %.

It seems to be feasible to use selected isolates of Trichoderma spp. for biological control of sclerotia of ß. cinerea also during the colder season.
Rate of Loss of Infectivity of Maize Dwarf Mosaic Virus by Schizaphis graminum Rondani After Different Acquisition Access Periods
Authors: Berger P. H. , Harris K. F. , Toler R. W.
Published: May 2008

The rate of loss of infectivity for greenbugs, Schizaphis graminum Rondani, carrying maize dwarf mosaic virus (MDMV) was similar for adult apterae and alates regardless of the acquisition access period (AAP) given. The rate was rapid during the first 2 h post‐acquisition and then decreased. Weighted least squares linear regression of log % transmission were plotted against retention‐time intervals to obtain regression slopes for each of the AAP groups tested (1, 3, 17, and 30 min). There were no significant differences among the regression slopes using F‐test comparisons.

In serial transmission trials, transmission frequencies among aphids allowed 1‐min or 30‐min timed acquisition probes followed by 30‐see or 1‐min timed inoculation probes were not significantly different when statistical tests that quantify categorical data were applied. This suggests little difference in the amount of virus obtained by these groups of aphids.

Transmission and retention data are discussed in relation to the two principal theories of the mechanism of non‐persistent virus transmission by aphids. Transmission of MDMV by the greenbug by a two mechanism process (stylet‐borne and ingestion‐egestion) is not confirmed.
Detection of Citrus Tristeza and Greening in Pakistan Through Electron Microscopy
Authors: Grimaldi V. , Catara A.
Published: May 2008

An electron microscopic investigation was carried out on citrus fruits and leaves collected during a survey in Pakistan. Thread‐like particles of citrus tristeza virus (CTV) were ascertained in phloem tissues of the columclla, whereas the bacterium associated with greening was detected in sieve tubes of the columella and in leaf midribs of trees showing typical yellow vein, fruit maiformation an decline. CTV was also confirmed by ELISA tests.
Infection of Onion by the White Rot Pathogen, Sclerotium cepivorum
Authors: Stewart A. , Fullerton R. A. , Sutherland P. W.
Published: May 2008

Infection of onion tissue by Sclerotium cepivorum occurred from germ tubes penetrating between adjacent epidermal cell walls or directly, via penetration pegs produced from slightly swollen hyphal tips or from beneath dome shaped infection cushions. After passing through the cuticle, the infection peg enlarged to form an infection hypha within the primary cell wall. Extensive degradation of the epidermal cell wall occurred, often at a distance of 2–3 cells from the advancing hyphae.

As infection advanced, hyphae spread rapidly from the epidermis to the cortex growing between and within dead/dying host cells. Extensive host cell death resulted in localized collapse of the tissue around infection points. Complete colonization of the internal tissues of the root and stem base occurred within 5–7 days of inoculation.
Identification, Distribution and Vector Population Dynamics of Barley Yellow Dwarf Virus in Three Cereal‐Producing Areas of Spain
Authors: Fereres A. , Lister R. M. , Castanera P. , Foster J. E.
Published: May 2008

ELISA‐based surveys during 1985–87 in three major cereal‐growing areas of Spain confirmed the presence of barley yellow dwarf virus (BYDV). Samples of small grain cereals and grasses with and without BYDV‐like symptoms were collected in the central, southwestern, and northeastern Spain. Infections were found in all cereal species sampled and in some grasses. About 37 % of the samples collected in 1985 were infacted with isolates of the PAV serotype. Isolates of the RPV serotype were less common, and were detected only in samples from the central region at El Encin, Madrid. Only a single sample, collected from El Encin in 1987, was unequivocally diagnosed as containing an isolate of the MAV serotype.

Aphid vector population dynamics was monitored during fall and winter of 1984–87 in the central region. Rhopalosiphum padi L. appeared to be the most abundant species during fall and winter months, infesting grasses and volunteer wheat. Other species present were Sitobion avenae (F.), Metopolophium dirhodum (Walker) and Rhopalosiphum maidis (Fitch). Both R. padi and S. avenae seem to be anholocyclic in the central region of Spain, and are able to remain and reproduce on wheat volunteers and grasses until the beginning of spring. S, avenae populations increase quickly on wheat volunteers in April, while populations of R. padi remain low. Therefore, spread of S. avenae‐transmitted BYDV types to neighbouring cereal fields seem more likely to occur than spread of other types. Other possible virus reservoirs, such as maize, also need investigation for a better understanding of BYDV epidemiology in the central and other cercal‐growing areas of Spain.
Assessment of Red Core Resistance of Strawberry Using Enzyme‐Linked Immunosorbent Assay (ELISA)
Authors: Mohan S. B. , Kennedy D. M. , Duncan J. M.
Published: May 2008

There was a strong correlation between measurements of red core disease of strawberry, assessed as percentage lengths of the adventitious roots with red steles, and ELISA values obtained from the same root systems using a polyclonal antiserum raised to Phytophthora fragariae. ELISA grouped twelve host cultivar/pathogen isolate combinations into three categories, highly resistant, partially resistant and susceptible, which agreed with disease incidence after inoculation.
Genetic Adaptation of Erysiphc graminis f. sp. Hordei to Barley with Partial Resistance
Authors: Newton A. C.
Published: May 2008

Ten Isolates of powdery mildew were tested on three spring barley cultivars known to express partial resistance and on Golden Promise. Measurements of colony lengths were made under several different environments and compared with similar data produced from several cultivars containing one of two major resistance genes. Significant isolate, cultivar and environment interactions were recorded and one isolate in particular showed adaptation to a partially resistant cultivar.

Measurements of infection frequency were also made under two temperature regimes. Again significant isolate, cuitivar and temperature interactions were recorded and the same isolate showed adaptation to the same partially resistant cultivar. This indicates that adaptation to a source of partial resistance can be found amongst unselected isolates and that pleiotropically adapted genotypes may rapidly overcome such resistance in the field following its widespread deployment. Other genes for resistance were detected in the major gene cultivars, including partial resistance in the ml‐v genotypes.
Influence of Temperature, Wetness Duration, and Leaf Type on the Quantification of Monocyclic Parameters of Bean Rust
Authors: Mendes B. M. J. , Bergamin Filho A.
Published: May 2008

Monocyclic parameters of bean rust (Uromyces phaseoli var. typical) were quantified in growth chambers, on rwo bean cultivars for three temperatures (17, 21, and 25 °C), two types of leaves (unifoliolate and trifoiiolate leaves), and nine leaf wetness periods (0, 4, 7, 10, 13, 16, 19, 22, and 25 hrs). The expression of disease was greatly influenced by past‐inoculation temperatures. The incubation and latent periods were shortest at 21 °C for both cultivars and leaf types. For both cultivars, trifoiiolate leaves were more susceptible than unifoliolate leaves. A wetness period of at least four hours was required for disease to occur. The maximum disease efficiency for both cultivars occurred with 22 hrs of leaf wetness at 17 °C. The disease efficiencies for temperatures of 17–29 °C and leaf wetness periods of 0–25 hrs were adequately described by a response‐surface model. Because of the great influence of temperature and leaf wetness on infection, bean rust is unlikely to occur at high temperatures (> 25°C) and short leaf wetness periods (< 7 hrs).
The Pathogenesis‐Related Proteins of Phsseolus Bean
Authors: RedolfiA. P. , Cantisani  , Migheli Q.
Published: May 2008

Seven acidic low molecular weight pathogenesis‐related (PR) proteins from tobacco necrosis virus‐infected Phaseolus bean leaves were isolated, purified and partially characterized. The proteins could ba classified following the nomenclature of Antoniwet al. (1980) for tobacco PR proteins. Three groups are thus proposed, corresponding to molecular sizes of 16, 27 and 31 kD, very close to the values of three groups proposed for tobacco. Tentative correspondences between the PR proteins here described and those previously reported by other authors are also proposed.
Coat Protein‐derived Small Particles in a Tombusvirus from River Lato
Authors: Gallitelli D. , Di Franco A. , Vovals C. , Martelli G. P.
Published: May 2008

A new tombusvirus cleariy distinguishable from other members of the group was isolated in Apulia from river Lato and therefore referred to as Lato River Tombusvirus (LRV). Purified virus preparations after storage for 5 months at 4°C in 20 mM phosphate buffer, pH 7.2, contained variable amounts of small particles (c. 17 nm in diameter) in addition to typical virus particles (c. 30 nm in diameter). LRV small particles were constituted by a single protein species with a tnol. wt of 29,000, did not contain nucleic acid and were not infective but proved to be serologically undistinguishable from ordinary virus particles. Attempts to artificially produce small particles by chemical orenzymatic treatments of full size LRV virions failed but their spontaneous production nder particularstorage conditions seems to be a remarkable feature of this virus as it does not occur with other definitive tombusviruses.
Effect of Different Strains of Soybean Mosaic Virus on Growth, Maturity, Yield, Seed Mottling and Seed Transmission in Several Soybean Cultivars
Authors: To J. C.
Published: May 2008

Eighty soybeans (Glyane max Merr) cultivars, includingx a resistant line Oxley 615 were each inoculated with seven streams of soybean mosaic virus SMV. Susceptible cultivers produced smaller plants with delaved maturity, and reduced seed yield relative to the non inoculared plants Someptible cultivars had.a higher level of morrled seeds and seat transmission ot SMV from the morrled seeds than the resistance line Oxley 615.

The SMV strain cultivar interaction was significant for all traits, suggsesting that soybean cultivars should be tested against specific SMV strains to determine their response to this virus.
Characteristics of Inhibition of Suppressive Soil Created hy Monoculture with Radish in the Presence of Rhizoctonia solani
Authors: Chern L. L. , Ko W. H.
Published: May 2008

Soils collected from five districts of Hawaii county were infested with Rhtzoctonia solani in small inoculum particles and successfully planted with radish to induce suppression, Suppressiveness was induced in some, but not all, replicates of all. soils. When fresh inoculum was added, suppressiveness was demonstrated in some, but not all, replicates of two soils, but not in the other three soils. Acidity of soil was not important in successful induction of suppression. Characteristics of induced suppression in soil from one site (S. Kohala) were further investigated.

Reduction of microbial population by heat treatment of suppressive soil completely nullified its inhibitory effect. The populations of actinomycetes, fungi in general and Trichoderma spp. in suppressive and conducive soil were not significantly different. However, the population of bacteria in suppressive soil was almost four times higher than that in conducive soil. The survival time of R. solani in suppressive soil was shorter than that in conducive soil. Hyphae of R. solani also lysed faster in suppressive soil than in conducive soil. It is suggested that suppressiveness of the South Kohala soil created by monoculture is due to enhanced competitive pressure generated by an increased bacterial population, which in turn causes the rapid autolysis of R. solani hyphae.
Mode of Sour Rot Formation as Inferred from Comparative Studies with Virulent and Avirulent Strains of Geotrichum candidum
Authors: Hershenhorn J. , Bher Leah , Barash I. , Arzee Tova
Published: May 2008

A comparative study between virulent and avinilent strains ot Geotrichum candidum was undertaken in order to identify mechanisms for virulence of this pathogen on letnons. The initial development of virulent and avirulent strains during the 48 h following inoculation, as measured by colony‐forming units, was similar. However, only virulent strains produced actively developing soft rot lesions whereas avirulent strains produced arrested dry lesions. Microscopical examination indicated that disorganization and maceration of the exocarp tissue preceded the penetration of fungal hyphae at all inoculation sites. Degradation of pectic substances progressed with maceration. Ultra.structural examination revealed cytoplasmic inclusions originated from projections of plastid membranes. Various tests for possible involvement of active defence mechanisms gave negative results. Production of endopolygalactutonase (PG) was significantly higher in virulent than in avirulent strains. When lemon fruits were treated at 80°C for 2min, active lesions were also developed by avirulent strains. The PG of the virulent strain was more effective than that of the avirulent in causing maceration of lemon albedo tissue and the heat treatment increased the rate of maceration with both enzyme preparations. It was suggested that the initial amount of PG produced in vivo and the sensitivity of the pectin in situ to this enzyme, are the main factors that govern virulence of G. candidum on citrus fruit.
Components Analysis of Race Non‐Specific Resistance to Blast Disease of Rice Caused by Pyricularia oryzae
Authors: Castano J. , MacKenzie D. R. , Nelson R. R.
Published: May 2008

A group of 69 rice cultivars with diverse degrees of resistance to rice blast disease (at least in a qualitative sense) was chosen for a detailed study of some components of race non‐specific resistance, i.e. relative disease efficiency, latent period, and sporulation capacity. Large differences amongst cultivars were found. The overlapping of the normal curves for the qualitative reaction and the components of race non‐specific resistance point out the difficulties of rapid screening for blast resistance by simple observation in the field. One approach to overcome these difficulties could be to use component(s) analysis in the evaluation of rice germplasm to identify parents or progeny having the attributes of race non‐specific resistance.
Production of Phytotoxic Sirodesmins by Aggressive Strains of Leptosphaeria maculans Differing in Interactions with Oil Seed Rape Genotypes
Authors: Badawy H. M. A. , Hoppe H. H.
Published: May 2008

Sirodesmins were extracted from culture filtrates of 3 aggressive strains of Leptosphaeria maculans which showed different specific interactions with the oilseed rape cultivars Quinta and Jet Neuf. Up to 8 compounds were detectable showing reactions on thin layer plates which are characteristic for sirodesmins. Sirodesmin PL, sirodesmin C, deacetylsirodesmin PL and deacetyl‐sirodesmin C were identified on the basis of their UV‐spectra, by various conversion reactions and by cochromatography with known standards. Two further compounds were tentatively identified as sirodesmin B and deacetylsirodesmin B on the basis of conversion reactions only. In the cultures of all strains sirodesmin PL was the main component, followed by deacetylsirodesmin PL, sirodesmin C, and deacetylsirodesmin C. These 4 metabolities were mainly responsible for the phytotoxic activity of all culture filtrates. They were systemically transported to leaves of root treated rape seedlings. No correlation was found between the production of the 4 main sirodesmins and the differential host parasite interactions of the 3 aggressive strains of Leptosphaeria maculans.
Effect of GA3 on the Phytotoxicity of Aldicarb and Carbofuran on Seedling Growth in Capsicum frutescens var. California Wonder and Rate of Root Knot Nematode Infestation
Authors: Singh S. P. , Maheshwari D. K.
Published: May 2008

The present investigation dealt with the effect of the two granular systemic nematicides aldicarb and carbofuran, individually and in combination with 100 mg · 1‐1 GA3, on plant growth and root knot formation in C. frutescens var. California Wonder. Both nematicides and GA3 were applied as a seed‐dip treatment. GA3 increased seed germination and seedling growth. All concentrations (2 to 20 g a.i. · 1‐1) of aldicarb and carbofuran, when applied independently, reduced seed germination and length of epicotyl and hypocotyl. However, application of these nematicides in combination with 100 mg · 1‐1 GA3 showed antagonistic behaviour.

All the treated seedlings were inoculated with 1000 nematode larvae of Meloidogyne incognita. Vegetative parameters of the plant were studied 15 days after transplantation. A combination of GA3 (100 mg · 1‐1) with different concentrations of nematicides showed a synergistic effect on treated plants. Root knot index in plants treated with nematicides was found to be reduced with increasing concentrations of both nematicides. Maximum reduction in root knot index was observed at highest dose (20 g a.i. · 1‐1) of both nematicides, when applied in combination with 100 mg · 1‐1 GA3. Proteolytic activities were decreased in plants treated with both aldicarb and carbofuran. Supplementation of the nematicides with GA3 resulted in an increase in enzyme activities of the treated plants. Toxic residues increased with increasing concentration of both nematicides, whereas it was reduced at highest concentration of both nematicides when applied in combination with GA3.
Base Composition of the DNA of Mycoplasma‐Like Organisms Associated with Various Plant Diseases
Authors: Kollar A. , Seemüller E.
Published: May 2008

DNA was isolated from periwinkle plants infected by various mycoplasma‐like organisms (MLOs), and from apple trees affected by apple proliferation. The DNA of the causal agents was separated from the host plant DNA by repeated bisbenzimide‐CsCl buoyant density gradient centrifugation which resulted in highly enriched MLO DNA bands characterized by a lower buoyant density than that of the host DNA. The MLO DNAs were hydrolyzed to free bases which were determined by HPLC. The analyses revealed a similar low G + C content as found in the DNAs of several culturable mycoplasmas and spiroplasmas. The values of the DNA of the agents of the diseases investigated were as follows: European aster yellows 23.0, periwinkle virescence 23.5, apple proliferation 23.7, rape virescence 24.2, and phyllody of Diplotaxis erucoidcs 26.2 mol % G + C, respectively. Methylated bases were detected in low amounts only.
Evaluation of Bacillus subtilis for Potential Control of Apple Replant Disease
Authors: Utkhlde R. S. , Li T. S. C.
Published: May 2008

Apple seedlings (ev. Melntosh were stunted when grown in pasteurized field soil to which four fungi, previously isolated from apple replant disease (ARD) soil, were added. Twenty‐one isolates of Bacillus sulnths produced inhibition zones in vitro against 20 ARD fungi. Isolate BACT‐1 ol B. subtilis showed significant antagonism against 17 fungi isolated from ARD soil on potato dexirose agar and apple plant height was increased in its presence in pesteurized and fertilized soil in glasshouse pot tests. Plant height also increased in the presence of isolate F.BW‐4 of B.subtilis.in pasteurized and fertilized soil in glasshouse pot tests but EBW‐4 liid not show antagonism against most of the ARD tungi in vitro. The growth of apple seedlings was stunted in the presence of 12 isolates of B. subtilis. However, fertilization of non pasteurized soil with NPK 1l‐55‐0 reversed the stunting effect. Under field conditions, BACT‐1 and EBW‐4 isolates. led to increased shoot growth in unfertilized and unppasteurized ARD soil.
Biological Control of Basal Stem Rot of Chrysanthemum By Antagonists*
Authors: Tschen JohannesScheng‐Ming , Lee Yih‐Yun , Wu Wen‐Shi , Liu Shan‐Da
Published: May 2008

The basal stem rot of chrysanthemum caused by Rhizoctonia solani is an important chrysanthemum disease in Taiwan, Control of the disease using the antagonists of R.solani, including members of the genera Aspergillus, Gliocladium, Paecilomyces, Penicillhium, Tricboderma and Bacillus, was studied. The antagonists were grown in solid media or culture broths for preparations of rhe inoculums which were u.sed as soil amendments or coating materials for applications on the disease control. Sawdusts, rice husks and sawdust composts were used as supporting material to prepare the solid media. By planting of the chrysanthemums, the solid media growth with antagonists were put in the nursery sand beds, or the chrysanthemum cutting seedlings were coated with antagonists of culture broths; whilst the sand beds were inoculated with R. solani. The results indicated that all antagonists could protect the chrysanthemum from the infection of R. solani, and the effects of the solid media were higher than the culture broths. When the chrysanthemum seedlings were treated with the extracts of the antagonists, the disease could also be depressed. The different control effects on Rhizactonia disease of chrysanthemums resulted from the species of the antagonists and their delivery systems to be used.
The Role of Non‐Vectored Soil Transmission as a Primary Source of Infection by Pepper Mild Mottle and Cucumber Mosaic Viruses in Glasshouse‐Grown Capsicum in Australia
Authors: Pares R. D. , Gunn L. V.
Published: May 2008

Virus disease limit glasshouse production of capsicums in the Supraysia District of New South Wales. Symptoms develop on plants about 4 weeks after planting; and up to 83° of plants are infected. The major virus is cucumber mosaic (CMV) with some pepper mild niottle (PMMV) also present. Evidence is presented to show that the primary source of intection of both viruses is most likely to be debris from previous crops remaining in the soil. It demonstrates a previously unconsi‐dered mechanism tor survival and spread of labile viruses such as CMV and the ecological ecological consequence of these results are considerable.
Nesoclutha declivata Homoptera Cicadellidae, Vector of Digitaria Streak Virus (Geminivirus) in Vanuatu
Authors: Julia J. F. , Dollet M.
Published: May 2008

A geminivirus, the Digitaria Streak Virus (DSV) affects Digitaria sangninalis in Vanuatu. As this plant exists in certain foci of coconut foliar decay (FD), a disease with which a circular single‐stranded DNA is associated, the possibility of these two diseases having a common identity was considered. A study of the vectorial aspects of these two diseases has shown that Myndus taffini (Cixiidae) is a vector of coconut FD and that it does not transmit DSV. Nesoclutha declivata (Cicadellidae) transmits DSV on Digitaria.
Distribution of Phytophthora cinnamomi‐Supprcssive Soil in Nature
Authors: Ko W. H. , Shiroma S. S.
Published: May 2008

Phytophthora cinnamomi‐suppressivc soils were found to be widely distributed in nature. About 40 % of soil samples collected from locations with different vegetation, soil type or elevation throughout the island of Hawaii were suppressive to chlamydospore germination of Phytophthora cinnamomi. Soil samples collected from the same general areas varied greatly in degree of suppressive‐ness to P. cinnamomi, ranging from conducive to strongly suppressive. Among the 155 soil samples tested, those with pH close to 4 or 8 tend to be more suppressive to P. cinnamomi than those with pH close to 6.
Relationship between Climatic Variables during Early Flowering of Sorghum and the Incidence of Sugary Disease caused by Sphacelia sorghi
Authors: McLaren N. W. , Wehner F. C.
Published: May 2008

The relationship between sugary disease incidence and six climatic variables during the early stages of flowering was determined in field trials conducted over three seasons. Daily maximum temperature was highly significantly correlated with sugray disease incidence and accounted for 83 % of the variation observed in disease incidence. The critical period for infection was limited to 5 days after commencement of pollen shed. Deviations from the temperature × sugary disease model occurred in late flowering plots. These were correlated with low temperatures during the 2 weeks prior to pollen shed and, thus, possibly, a reduction in pollen vigour.
The Development of Eyespot on Seedling Leaf Sheaths in Winter Wheat and Winter Barley Crops Inoculated with W‐type or R‐type Isolates of Pseudocercosporella herpotrichoides
Authors: Goulds A. , Fitt B. D. L.
Published: May 2008

In 1986–88 the development of eyespot lesions in winter wheat or winter barley differed plots inoculated with W‐type isolates of Pseudocercosporella herpotrichoides and plots inoculated with R‐type isolates. In the spring of 1986, after a cold winter, the incidence (%shoots infected) and severity (number of leaf sheaths penetrated) of eyespot lesions in wheat before GS 30/31 were greater in plots inoculated with R‐type isolates than in those inoculated with W‐type isolates. In 1987, after amild winter, eyespot incidence and severity in both wheat and barley were initially greater in W‐type plots than in R‐type plots. However, by GS 30/31 or 1987. In 1988, when the crop was October‐sown, eyespot incidence and severity were greater in W‐type than in R‐type plots at GS 30/31. Differences in eyespot incidence and severity between W‐type and R‐type plots were smaller in barley than in wheat. Both the incidence and severity of eyespot were greater in early‐sown than in late‐sown plots. Seed rate, had little effect on the rate of lesion development in 1987, but in 1988 the rate of penetration was less at the low seed rate for both wheat and barley.
Production and Characterization of Monoclonal Antibodies Specific to Closterovirus‐like Particles Associated with Grapevine Leafroll Disease
Authors: Zimmermann D. , Sommermeyer G. , Walter B. , Van Regenmortel M. H. V.
Published: May 2008

Three hybridoma lines secreting monoclonal antibodies to a closterovirus‐like particle (GLRV 3) associated with grapevine leafroll disease were produced. One of the antibody (MAbt) reacted with one extremity of the filamentous virus particle whereas the other two (MAb2 and 3) reacted with the entire surface of the virus particle.

Using MAb2 in ELISA it is possible to detect 46 of the 50 GLRV‐3 isolates. In order to detect all the 50 isolates, it is necessary to use MAb1 in ELISA in conjunction with polyclonal antibodies.

In immunoblotting, the three MAbs recognized a 43 Kd viral protein.